JP4602900B2 - Optical transmitter / receiver in single-core bidirectional wavelength division multiplexing optical communication system - Google Patents

Description

  The present invention relates to an optical transmission / reception apparatus for a single-core bidirectional wavelength division multiplexing optical communication system.

  Conventionally, wavelength division multiplexing optical communication systems have required optical transceivers having different device configurations according to wavelength bands. FIG. 1 shows a configuration example of a single-core bidirectional wavelength division multiplexing optical communication system using a media converter currently on the market. The system 100 includes two optical transmission / reception devices 110 and 130 that are connected via an optical transmission line 120 and have different device configurations.

The optical transceiver 110 includes an optical transmitter 112 having a wavelength λ ₁ (for example, a 1.3 μm band), an optical receiver 114 having a wavelength λ ₂ (for example, a 1.5 μm band), and light having wavelengths λ ₁ and λ ₂ . And a wavelength multiplexer / demultiplexer 116 for multiplexing and demultiplexing the signal. On the other hand, the optical transceiver 130 includes an optical transmitter 132 having a wavelength λ ₂ (1.5 μm band) and an optical receiver 134 having a wavelength λ ₁ (1.3 μm band) (the optical receiver has a wide usable wavelength band). Therefore, the optical receiver 114 may be used although the conversion efficiency is reduced), and a wavelength multiplexer / demultiplexer 136 that multiplexes / demultiplexes the optical signals having the wavelengths λ ₁ and λ ₂ . Thus, in these optical transmitter / receivers, the wavelength configurations of the optical transmitter and the optical receiver are reversed.

This system configuration, the transmission of an optical signal from the optical transceiver 110 to the optical transceiver 130, using the wavelength lambda _1, the transmission of the optical signal from the optical transceiver 130 to the optical transceiver 110, the wavelength lambda ₂ Communication will be performed using. Thus, in this system configuration, there is a problem that two types of optical transmission / reception devices having different device configurations must be prepared between the opposing devices.

  In order to solve this problem, a method for making a single type of configuration of an optical transceiver is known (Patent Document 1). FIG. 2 shows a configuration example of a single-core bidirectional wavelength division multiplexing optical communication system using such an optical transceiver. The system 200 includes two optical transmission / reception devices 210 and 230 that are connected via an optical transmission line 220 and have the same device configuration.

The optical transceiver 210 includes an optical transmitter 211 having a wavelength λ ₁ (eg, 1.3 μm band), an optical transmitter 212 having a wavelength λ ₂ (eg, 1.5 μm band), and an optical receiver 214 having a wavelength λ _1. And an optical receiver 215 having a wavelength λ ₂ . The optical transceiver 210 is further connected to an optical switch 216 that switches between the optical transmitter 211 and the optical receiver 214, an optical switch 217 that switches between the optical transmitter 212 and the optical receiver 215, and the optical switches 216 and 217. And a wavelength multiplexer / demultiplexer 218 that multiplexes / demultiplexes optical signals of wavelengths λ ₁ and λ ₂ .

Similarly, the optical transceiver 230 includes an optical transmitter 231 having a wavelength λ ₁ (1.3 μm band), an optical transmitter 232 having a wavelength λ ₂ (1.5 μm band), and an optical receiver 234 having a wavelength λ _1. and an optical receiver 235 of the wavelength lambda _2. The optical transceiver 230 is further connected to an optical switch 236 that switches between the optical transmitter 231 and the optical receiver 234, an optical switch 237 that switches between the optical transmitter 232 and the optical receiver 235, and the optical switches 236 and 237. And a wavelength multiplexer / demultiplexer 238 for multiplexing / demultiplexing optical signals of wavelengths λ ₁ and λ ₂ .

With this system configuration, for transmission of an optical signal from the optical transmission / reception device 210 to the optical transmission / reception device 230, the wavelength λ ₁ is used through the setting of the optical switches 216 and 236, and Is transmitted using the wavelength λ ₂ through the setting of the optical switches 217 and 237. As described above, in this system configuration, by appropriately setting the optical switch, it is possible to use the optical transmission / reception device having the same device configuration between the opposing devices.

JP 63-169132 A

  As described above, the configuration of FIG. 1 requires two types of optical transmission / reception devices having different device configurations between the opposing devices, and there is no compatibility between the devices, which is inconvenient from the viewpoint of maintenance operation. Further, in the configuration of FIG. 2, it is possible to use an optical transmission / reception device having the same device configuration between opposing devices, but there are optical transmitters and optical receivers that are not used in the device. It is disadvantageous from the viewpoint of economy.

  The present invention has been made in view of such a problem, and the object of the present invention is to make it possible to make the same device configuration between opposing devices in a single-core bidirectional wavelength division multiplexing optical communication system. It is in providing the optical transmitter / receiver excellent in.

In order to achieve such an object, the present invention is applied to a single-core bidirectional wavelength division multiplexing optical communication system in which optical transceivers having the same configuration are connected via an optical transmission line. An optical transmitter / receiver capable of setting an optical signal to be transmitted to one of the first and second wavelengths, and capable of receiving any optical signal of the first and second wavelengths A wavelength multiplexer / demultiplexer that multiplexes / demultiplexes the optical signals of the first and second wavelengths, and transmits the optical signal of the first wavelength between the optical transmission line and the optical receiver; A wavelength multiplexer / demultiplexer having one input / output port and a second input / output port that transmits an optical signal of the second wavelength between the optical transmission line, the optical transmitter, and the optical receiver The connection state between the optical multiplexer and the first and second input / output ports of the wavelength multiplexer / demultiplexer. And a 2 × 2 optical switch capable of switching to chromatography, so that the light signal transmitted from the optical transmitter is output to the optical transmission line, and the wavelength of the optical transmitter of the 2 × 2 optical switch The connection state is set .

The invention according to claim 2 further includes a control circuit for setting a transmission wavelength and a reception wavelength with the optical transmission / reception apparatus facing each other in the optical transmission / reception apparatus according to claim 1, wherein the control circuit includes: , One of the first and second wavelengths is set as a transmission wavelength at a random time interval, and the other wavelength is set as a reception wavelength, and a predetermined level of light is set at the set reception wavelength. When a signal is detected, it operates to establish communication at the set transmission wavelength and reception wavelength .

The invention according to claim 3 further includes a control circuit for setting a transmission wavelength and a reception wavelength with the optical transmission / reception apparatus facing each other in the optical transmission / reception apparatus according to claim 1, wherein the control circuit includes: The first wavelength and the second wavelength are randomly selected at a predetermined time interval or a random time interval and set as a transmission wavelength, and the other wavelength is set as a reception wavelength. When an optical signal of a predetermined level is detected at the set reception wavelength, it operates so as to establish communication at the set transmission wavelength and reception wavelength .

The invention described in Claim 4 is the optical transmitter-receiver according to any one of claims 1 to 3, wherein the optical transmitter can be set to either of said first and second wavelength by a temperature control It is characterized by comprising a simple laser diode.

According to a fifth aspect of the present invention, in the optical transceiver according to any one of the first to third aspects , the optical transmitter includes a first laser diode that outputs an optical signal having the first wavelength. And a second laser diode that outputs an optical signal of the second wavelength.

The invention of claim 6 is an optical transceiver according to claim 5, wherein the first and second laser diode is characterized in that it is integrated on a single chip.

The invention according to claim 7 is an optical transmission / reception apparatus applicable to a single-core bidirectional wavelength division multiplexing optical communication system in which optical transmission / reception apparatuses having the same configuration are connected via an optical transmission line. An optical transmitter having a broadband light source capable of outputting an optical signal including a second wavelength; an optical receiver capable of receiving any optical signal of the first and second wavelengths; and the first and second A wavelength multiplexer / demultiplexer that multiplexes / demultiplexes an optical signal having a wavelength of the first, and a first input / output port that selectively transmits the optical signal having the first wavelength to / from the optical transmission line; A wavelength multiplexer / demultiplexer having a second input / output port that selectively transmits an optical signal of the second wavelength to and from an optical transmission line, the optical transmitter and the optical receiver, and the wavelength The connection state between the first and second input / output ports of the multiplexer / demultiplexer can be switched to cross or through And a a 2 × 2 optical switch, so that the optical signal of the first or second wavelength is transmitted from the optical transmitter is output to the optical transmission line, the connection state of the 2 × 2 optical switch Is set .

The invention according to claim 8 is the optical transceiver according to claim 7, further comprising a control circuit for setting a transmission wavelength and a reception wavelength with the opposing optical transceiver, wherein the control circuit includes: The connection state of the 2 × 2 optical switch is set to cross or through at random time intervals, and one of the first and second wavelengths is set as a transmission wavelength, and the other wavelength is set as a reception wavelength. And configured to operate so as to establish communication at the set transmission wavelength and reception wavelength when an optical signal of a predetermined level is detected at the set reception wavelength .

The invention according to claim 9 is the optical transceiver according to claim 7 , further comprising a control circuit for setting a transmission wavelength and a reception wavelength with the opposing optical transceiver, wherein the control circuit includes: The connection state of the 2 × 2 optical switch is set to cross or through at a predetermined time interval or at a random time interval, and one of the first and second wavelengths is randomly selected and set as a transmission wavelength. The other wavelength is set as a reception wavelength, and when an optical signal of a predetermined level is detected at the set reception wavelength, communication is established at the set transmission wavelength and reception wavelength. It is characterized by operation .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 3 shows a basic configuration example of an optical transceiver in a single-core bidirectional wavelength division multiplexing optical communication system according to the present invention. This optical transceiver 310 includes an optical transmitter 312 corresponding to both optical signals having wavelengths λ ₁ (for example, 193.1 THz) and λ ₂ (for example, 193.3 THz), and both wavelengths λ ₁ and λ ₂ . An optical receiver 314 corresponding to an optical signal, a 2 × 2 optical switch 316 that switches a transmission / reception path, and a wavelength multiplexing / demultiplexing device 318 that multiplexes / demultiplexes optical signals of wavelengths λ ₁ and λ ₂ are provided. . The optical transmitter / receiver 310 can switch the connection state of the optical switch 316 between through and cross according to the wavelength used for transmission / reception. By using an optical transceiver having such a basic configuration, optical transceivers having the same configuration can be used between opposing devices. Also, compared with the prior art, each apparatus is economical because the number of optical transmitters, optical receivers, and optical switches can be reduced. Specific embodiments and alternative embodiments thereof will be described in detail below.

  FIG. 4 shows the configuration of the wavelength division multiplexing optical communication system according to the first embodiment of the present invention. In this system 400, two optical transmission / reception devices 410 and 430 having the same device configuration are connected via an optical transmission line 420.

  The optical transceiver 410 includes a distributed feedback laser diode (DFB-LD) 412 that oscillates in a single mode and whose wavelength can be varied according to temperature, a circuit 413 that controls the temperature of the DFB-LD, and a DFB-LD. An optical receiver 414 that can receive an optical signal in a variable wavelength range, a 2 × 2 optical switch 416 that switches a transmission / reception path, and a wavelength multiplexer / demultiplexer that multiplexes / demultiplexes optical signals of two different wavelengths 418.

  Similarly, the optical transmitter / receiver 430 includes a distributed feedback laser diode (DFB-LD) 432 that oscillates in a single mode and whose wavelength can be varied according to temperature, a circuit 433 that controls the temperature of the DFB-LD, An optical receiver 434 that can receive an optical signal in the wavelength variable range of the DFB-LD, a 2 × 2 optical switch 436 that switches a transmission / reception path, and a wavelength multiplexing that multiplexes and demultiplexes optical signals of two different wavelengths. And a duplexer 438.

  In the DFB-LD, for example, when the temperature is changed by 1 ° C., the wavelength changes by about 0.1 nm (12.5 GHz). In this case, when the temperature of the DFB-LD is changed by 16 ° C. by the temperature control circuit, the oscillation wavelength changes by 200 GHz. Correspondingly, a wavelength multiplexer / demultiplexer that can appropriately multiplex / demultiplex optical signals at intervals of 200 GHz is used.

  This wavelength interval can be set according to the variable temperature range by the temperature control circuit and the wavelength transmission characteristics of the optical communication system. For example, if the LD operating temperature is from 0 ° C. to 100 ° C., the variable temperature range is about 100 ° C. or less, so the practical wavelength variable range is limited to 10 nm (1250 GHz). Further, when considering the wavelength grid of ITU recommendation, the wavelength interval of 12.5, 25, 50, 100, 200, 400, and 800 GHz of DWDM is a candidate. It should be noted that a single optical receiver can be used because the characteristics of the optical receiver are usually hardly deteriorated by changing the wavelength in this range.

Specifically, in the configuration shown in FIG. 4, the temperature control circuit 413 sets the set temperature of the DFB-LD 412 to T ₁ and sets the oscillation wavelength of the DFB-LD 412 to λ ₁ . On the other hand, the temperature control circuit 433 sets the set temperature of the DFB-LD 432 to T ₂ and sets the oscillation wavelength of the DFB-LD 432 to λ ₂ . Further, one of the opposing devices, for example, the optical switch 416 of the optical transmission / reception device 410 is set to cross, and the other device, that is, the optical switch 436 of the optical transmission / reception device 430 is set to through.

By setting in this way, the wavelength λ ₁ is used for transmission of the optical signal from the optical transmission / reception device 410 to the optical transmission / reception device 430, and the transmission of the optical signal from the optical transmission / reception device 430 to the optical transmission / reception device 410 is performed. Communication can be performed using the wavelength λ ₂ . As described above, in this embodiment, the optical transceiver having the same configuration can be used between the opposed devices. In addition, each device uses only one optical transmitter, optical receiver, and optical switch, which is more economical than the conventional technology that realizes a single product type. In addition, although DFB-LD was mentioned here as an example of a wavelength variable light source, you may use other wavelength variable light sources, such as DBR.

  FIG. 5 shows a configuration of a wavelength division multiplexing optical communication system according to the second embodiment of the present invention. In this system 500, two optical transmission / reception devices 510 and 530 having the same device configuration are connected via an optical transmission line 520. The feature of this embodiment is that a laser diode array (LD array) composed of two DFB-LDs is used as a wavelength variable light source.

  The optical transceiver 510 receives a laser diode array (LD array) 512 composed of two DFB-LDs, a selection circuit 513 that selects one of the two DFB-LDs, and an optical signal in the wavelength range of the LD array. An optical receiver 514, a 2 × 2 optical switch 516 for switching transmission / reception paths, and a wavelength multiplexer / demultiplexer 518 for multiplexing / demultiplexing two different optical signals.

  Similarly, the optical transceiver 530 includes a laser diode array (LD array) 532 composed of two DFB-LDs, a selection circuit 533 that selects one of the two DFB-LDs, and an optical signal in the wavelength range of the LD array. 2 × 2 optical switch 536 for switching transmission / reception paths, and a wavelength multiplexer / demultiplexer 538 for multiplexing / demultiplexing two different optical signals.

FIG. 6 shows a configuration example of the LD array according to the present embodiment. In the configuration of FIG. 6A, the LD array 610a includes two DFB-LDs 612a and 614a, an optical coupler 616a coupled to the two DFB-LDs, and an optical amplifier 618a that amplifies an optical signal from the optical coupler 616a. And. The DFB-LDs 612 a and 614 a have different oscillation wavelengths λ ₁ and λ ₂ , respectively, and one DFB-LD is selected by the selection circuit 513. The selected DFB-LD is directly driven by the modulation signal, and a modulated optical signal having the wavelength λ ₁ or λ ₂ is output.

On the other hand, in the configuration of FIG. 6B, the LD array 610b includes two DFB-LDs 612b and 614b, an optical coupler 616b coupled to the two DFB-LDs, and a modulator that modulates light from the optical coupler 616b. 617b and an optical amplifier 618b that amplifies the optical signal from the modulator 617b. The DFB-LDs 612 b and 614 b have different oscillation wavelengths λ ₁ and λ ₂ , and one DFB-LD is selected by the selection circuit 513. The light from the selected DFB-LD is modulated by the modulator 617b with the modulation signal, and a modulated optical signal having the wavelength λ ₁ or λ ₂ is output. Note that the configuration of FIG. 6B is less affected by chirping due to modulation, and is advantageous for speeding up and lengthening.

In the configuration shown in FIG. 5, the wavelength of the modulated optical signal from the LD array 512 is set to λ ₁ by the selection circuit 513. On the other hand, the wavelength of the modulated optical signal from the LD array 532 is set to λ ₂ by the selection circuit 533. Further, one of the opposing devices, for example, the optical switch 516 of the optical transmission / reception device 510 is set to cross, and the other device, that is, the optical switch 536 of the optical transmission / reception device 530 is set to through.

By setting in this way, the wavelength λ ₁ is used for transmission of the optical signal from the optical transmission / reception device 510 to the optical transmission / reception device 530, and the transmission of the optical signal from the optical transmission / reception device 530 to the optical transmission / reception device 510 is performed. Communication can be performed using the wavelength λ ₂ . As described above, in this embodiment, the optical transceiver having the same configuration can be used between the opposed devices. In FIGS. 6A and 6B, an optical amplifier is used, but it is not always necessary if a desired optical power can be obtained.

  In this embodiment, in order to finely adjust the selected wavelength, the oscillation wavelength may be varied by combining the temperature control of each DFB-LD. In this embodiment, the economic efficiency can be improved by integrating the LD array on one chip. Further, in the configuration of this embodiment, even if one LD fails, the remaining LD can be used for communication, which has the advantage of device redundancy. Furthermore, since two LDs are used, there is a possibility that a wide wavelength interval of 20 nm, which is adopted not only in DWDM but also in CWDM, can be realized.

  FIG. 7 shows the configuration of a wavelength division multiplexing optical communication system according to the third embodiment of the present invention. In this system 700, two optical transceivers 710 and 730 having the same device configuration are connected via an optical transmission line 720.

  The optical transmitter / receiver 710 includes a broadband light source 712 having a wide spectral width, an optical receiver 714 that can receive an optical signal in a predetermined wavelength range, a 2 × 2 optical switch 716 that switches a transmission / reception path, and a predetermined And a wavelength multiplexer / demultiplexer 718 that multiplexes / demultiplexes the optical signal having the wavelength.

  Similarly, the optical transmission / reception device 730 includes a broadband light source 732 having a wide spectrum width, an optical receiver 734 that can receive an optical signal in a predetermined wavelength range, a 2 × 2 optical switch 736 that switches a transmission / reception path, and the like. And a wavelength multiplexer / demultiplexer 738 for multiplexing / demultiplexing an optical signal having a predetermined wavelength.

  In this embodiment, for example, a broadband light source having a wide spectrum width of about 30 nm is used, and the spectrum is set so that the spectrum does not overlap between the opposing devices by setting the optical switch and the wavelength characteristics of the wavelength multiplexer / demultiplexer. it can.

Specifically, in the configuration shown in FIG. 7, by setting the optical switch 716 of the optical transceiver 710 to the cross, the port of the wavelength λ ₁ of the wavelength multiplexer / demultiplexer 718 is connected to the broadband light source 712, and the wavelength λ _Two ports are connected to the optical receiver 714. On the other hand, by setting the optical switch 736 of the optical transceiver 730 to “through”, the wavelength λ ₁ port of the wavelength multiplexer / demultiplexer 738 is connected to the optical receiver 734, and the wavelength λ ₂ port is connected to the broadband light source 732. To be.

By setting in this way, the wavelength λ ₁ is used for transmission of the optical signal from the optical transmission / reception device 710 to the optical transmission / reception device 730, and the transmission of the optical signal from the optical transmission / reception device 730 to the optical transmission / reception device 710 is performed. Communication can be performed using the wavelength λ ₂ . As described above, in this embodiment, the optical transceiver having the same configuration can be used between the opposed devices. In addition, each apparatus uses only one optical transmitter, optical receiver, and optical switch, which is more economical than the prior art.

  In this embodiment, since the optical spectrum having a desired wavelength is cut out from the broadband light source by the wavelength multiplexer / demultiplexer, the wavelength control of the light source for changing the wavelength as shown in the first and second embodiments is unnecessary. Become.

  FIG. 8 shows a configuration of a wavelength division multiplexing optical communication system according to Embodiment 4 of the present invention. In this system 800, two optical transmission / reception devices 810 and 830 having the same device configuration are connected via an optical transmission line.

  The optical transmission / reception device 810 includes a distributed feedback laser diode (DFB-LD) 812 that oscillates in a single mode and can change the wavelength depending on temperature, a circuit 813 that controls the temperature of the DFB-LD, and a DFB-LD. An optical receiver 814 that can receive an optical signal in a variable wavelength range, a variable wavelength filter 816 that can change a transmission wavelength, and an optical circulator 818 are provided.

  Similarly, the optical transmission / reception device 830 includes a distributed feedback laser diode (DFB-LD) 832 that can oscillate in a single mode and can change the wavelength depending on temperature, a circuit 833 that controls the temperature of the DFB-LD, An optical receiver 834 that can receive an optical signal in the wavelength variable range of the DFB-LD, a wavelength variable filter 836 that can change the transmission wavelength, and an optical circulator 838 are provided.

  The operations of the DFB-LD and the temperature control circuit are the same as in the first embodiment.

In the configuration shown in FIG. 8, the temperature control circuit 813 sets the set temperature of the DFB-LD 812 to T ₁ and sets the oscillation wavelength of the DFB-LD 812 to λ ₁ . On the other hand, the temperature control circuit 833 sets the set temperature of the DFB-LD 832 to T ₂ and sets the oscillation wavelength of the DFB-LD 832 to λ ₂ . Further, the transmission wavelength of the wavelength variable filter 816 of the optical transmission / reception device 810 is set to λ ₂ , and the transmission wavelength of the wavelength variable filter 836 of the optical transmission / reception device 830 is set to λ ₁ .

By setting in this way, the wavelength λ ₁ is used for transmission of the optical signal from the optical transmission / reception device 810 to the optical transmission / reception device 830, and the transmission of the optical signal from the optical transmission / reception device 830 to the optical transmission / reception device 810 is performed. Communication can be performed using the wavelength λ ₂ . As described above, in this embodiment, the optical transceiver having the same configuration can be used between the opposed devices. In addition, each apparatus uses only one optical transmitter, optical receiver, and optical switch, which is more economical than the prior art.

  In this embodiment, a 1 × 2 optical coupler can be used instead of the optical circulator. Further, the LD array described in the second embodiment may be used.

  FIG. 9 shows the configuration of a wavelength division multiplexing optical communication system according to the fifth embodiment of the present invention. In this system 900, two optical transmission / reception devices 910 and 930 having the same device configuration are connected via an optical transmission line 920.

  The optical transceiver 910 includes a broadband light source 912 having a wide spectral width, an optical receiver 914 that can receive an optical signal in a predetermined wavelength range, and two wavelength variable filters 915 and 916 that can change the transmission wavelength. And an optical circulator 918.

  Similarly, the optical transmission / reception device 930 includes a broadband light source 932 having a wide spectrum width, an optical receiver 934 that can receive an optical signal in a predetermined wavelength range, and two wavelength variable filters that can change the transmission wavelength. 935 and 936, and an optical circulator 938.

  In the present embodiment, as in the third embodiment, a broadband light source having a wide spectral width of 30 nm is used, and the transmission wavelength of the wavelength tunable filter is adjusted so that the spectra do not overlap between the opposing devices. Can do.

Specifically, in the configuration shown in FIG. 9, the transmission wavelength of the wavelength variable filter 915 of the optical transmission / reception device 910 is set to λ ₁ , and the transmission wavelength of the wavelength variable filter 935 of the optical transmission / reception device 930 is set to λ ₂ . Further, the transmission wavelength of the wavelength variable filter 916 of the optical transmission / reception device 910 is set to λ ₂ , and the transmission wavelength of the wavelength variable filter 936 of the optical transmission / reception device 930 is set to λ ₁ .

By setting in this way, the wavelength λ ₁ is used for transmission of the optical signal from the optical transmission / reception device 910 to the optical transmission / reception device 930, and conversely, for transmission of the optical signal from the optical transmission / reception device 930 to the optical transmission / reception device 910. Can communicate using the wavelength λ ₂ . As described above, in this embodiment, the optical transceiver having the same configuration can be used between the opposed devices. In addition, each apparatus uses only one optical transmitter, optical receiver, and optical switch, which is more economical than the prior art.

  In this embodiment, a 1 × 2 optical coupler can be used instead of the optical circulator. Further, in this embodiment, the wavelength control of the light source as shown in the fourth embodiment is not necessary. Furthermore, since the broadband light source is incoherent light, it has a feature that it has excellent reflected light resistance compared to coherent light such as DFB-LD. Therefore, when the amount of reflection on the transmission line is relatively small, it is possible to reduce the wavelength tunable filter on the optical receiver side.

(Wavelength setting method in wavelength division multiplexing optical communication system)
Next, a method for mutually setting the wavelengths used for transmission / reception between the optical transmission / reception apparatuses facing each other in each of the above-described configurations will be described. FIG. 10 shows an optical transmission / reception apparatus to which a control circuit 1000 for performing wavelength setting is added in the basic configuration of the present invention shown in FIG. The control circuit 1000 controls the wavelength of the optical transmitter 312 and the path of the optical switch 316 to operate so as to automatically set the wavelength with the opposite device when the power is turned on.

  According to an embodiment of the present invention, when the control circuit 1000 continues to select the same wavelength between opposing devices at the same time, or when a received optical signal is lost due to a transmission line break or a failure of the opposing device, The operation of continuously switching the set wavelength can be avoided. Hereinafter, the operation of the control circuit according to the present invention will be described based on the configuration of the first embodiment described above (FIG. 4). However, it is noted that the principle of the present invention can be applied to other embodiments as well. I want.

  FIG. 11 shows a wavelength division multiplexing optical communication system including a control circuit for setting a wavelength in the configuration of the first embodiment (FIG. 4) of the present invention. In this system 1100, an optical transmission / reception device 1110 provided with a control circuit 1010 and an optical transmission / reception device 1130 provided with a control circuit 1030 are opposed to each other via a transmission line 420. The control circuit 1010 controls the oscillation wavelength of the DFB-LD 412 via the temperature control 413 and sets the transmission / reception wavelength by selecting the path of the optical switch 416. Similarly, the control circuit 1030 controls the oscillation wavelength of the DFB-LD 432 via the temperature control 433 and sets the transmission / reception wavelength by selecting the path of the optical switch 436.

The devices 1110 and 1130 perform a wavelength setting operation when the power is turned on or reset. For example, when the device 1110 is powered on, the optical receiver 414 detects the presence or absence of a received optical signal. When a predetermined wavelength (for example, λ ₂ ) is detected, the apparatus 1110 sets the wavelength (λ ₁ ) of the transmission optical signal by the control circuit 1010 corresponding to the detected wavelength. When the predetermined wavelength is not detected, the device 1110 sets the transmission optical signal to a predetermined wavelength (for example, λ ₁ ) by the control circuit 1010, and the wavelength (λ ₂ ) corresponding to the wavelength from the opposite device 1130. Wait for the received optical signal. When an optical signal with a corresponding wavelength (λ ₂ ) is received from the opposite device 1130, transmission / reception is started with the optical signal of each wavelength. When an optical signal having a corresponding wavelength (λ ₂ ) is not received from the opposing device 1130, the above operation is repeated again after a predetermined time has elapsed.

However, in such an operation, for example, when the devices 1110 and 1130 are turned on at the same time and an optical signal is transmitted at the initial wavelength λ ₁ at the same time, the same operation is repeated after a predetermined time. As a result, the wavelength setting operation between the devices enters an infinite loop, and wavelength setting is not performed forever. Therefore, in the present invention, this problem is avoided by setting the repetition interval of the wavelength setting operation of each device at random by the control circuit.

FIG. 12 conceptually shows an example of the wavelength setting operation between the opposed optical transmission / reception apparatuses. As shown in the figure, it is assumed that the devices A and B facing each other at the time t ₀ simultaneously transmit optical signals having the same wavelength λ ₁ by turning on the power, for example. In this case, both of these apparatuses do not receive the wavelength λ ₂ corresponding to the wavelength λ ₁ of the transmission optical signal. Therefore, the devices A and B each independently select a random time, and after that time has elapsed, the wavelength is again switched to λ ₂ for transmission. FIG. 12 shows a case where the same wavelength λ ₂ is switched by chance at the same time t ₁ . In FIG. 12, device A then switches the wavelength to λ ₁ again at time t ₂ after a lapse of random time. At this time, the device B detects the optical signal having the wavelength λ ₁ from the device A since the randomly set time has not yet elapsed. Thereby, the apparatus B sets the wavelength of the transmission optical signal to the wavelength corresponding to the wavelength λ ₁ of the received optical signal, that is, λ ₂ . Then, the device A detects the optical signal having the wavelength λ ₂ set by the device B, whereby the devices A and B enter a state where they can communicate with each other.

  In FIG. 12, the probability of both devices switching to the same wavelength simultaneously is reduced by setting the wavelength switching time interval at random, but the time interval is set randomly as shown in FIG. Instead, the wavelength may be switched randomly at predetermined time intervals. Further, these may be combined so that the time and wavelength are switched randomly.

  Next, an example of a detailed flow of the wavelength setting operation will be described with reference to FIG. 14, taking as an example the case of switching the time interval at random.

In S100, the optical transmitter / receiver is powered on, and in S102, the value of the counter x of the number of retransmissions is initialized to zero. Next, in S104, the transmission / reception wavelength is set to an initial value (for example, transmission wavelength λ ₁ ), and in S106, a predetermined received optical signal (wavelength λ ₂ ) is detected. If a predetermined optical signal is detected, the corresponding transmission optical signal (λ ₁ ) is set in S108, and synchronization is attempted to be established in S110. When synchronization is established, communication is started at each transmission / reception wavelength in S112. If the signal is interrupted for some reason during communication, the process returns to S102 and the operation is reset.

  If synchronization is not established in S110, transmission and reception are continued and an alarm is issued in S114. If synchronization is established during this time, the process proceeds to S112 and communication is started. If synchronization is not established even after a predetermined time has elapsed, or if the signal is interrupted during that time, the process returns to S102 and the operation is reset. The

In S106, when the predetermined reception optical signal (wavelength lambda ₂₎ is not detected, S116, the random predetermined wavelength lambda ₁ of the optical signal by a selected time is transmitted to a predetermined received optical signal (wavelength lambda ₂ ) Is detected. If a predetermined received optical signal is detected before the randomly selected time elapses, the process proceeds to S110 and an attempt is made to establish synchronization. If the predetermined received optical signal is not detected even after the randomly selected time has elapsed, the transmission / reception wavelength is switched (transmission wavelength λ ₂ ) in S118, and the predetermined received optical signal (wavelength λ ₁ ) is determined in S120. Detection is performed. If a predetermined optical signal is detected, a corresponding transmission optical signal (λ ₂ ) is set in S122, and establishment of synchronization is attempted in S124. When synchronization is established, communication is started at each transmission / reception wavelength in S126. If the signal is interrupted for some reason during communication, the process returns to S102 and the operation is reset.

  If synchronization is not established in S124, transmission and reception are continued and an alarm is issued in S128. If synchronization is established during this time, the process proceeds to S126 and communication is started. If synchronization is not established even after a predetermined time has elapsed, or if the signal is interrupted during that time, the process returns to S102 and the operation is reset. The

In S120, when the predetermined reception optical signal (wavelength lambda ₁₎ is not detected, S130, the random predetermined wavelength lambda ₂ of the optical signal by a selected time is transmitted to a predetermined received optical signal (wavelength lambda ₁ ) Is detected. If a predetermined received optical signal is detected before the randomly selected time elapses, the process proceeds to S124 to try to establish synchronization. If the predetermined received optical signal is not detected even after the randomly selected time has elapsed, the retransmission mode is set in S132, the value of the counter x of the number of retransmissions is incremented by 1, and the number of retransmissions x is determined in S134. It is confirmed whether the maximum number of transmissions M has been reached. If the maximum number of transmissions has not been reached, the process returns to S104, and the wavelength setting operation is repeated again. If the maximum number of transmissions has been reached, transmission / reception is continued and an alarm is issued in S136. During this time, if a predetermined optical signal is detected, the process proceeds to S124 to attempt to establish synchronization. Table 1 summarizes the wavelength setting operations by such a control circuit.

  In Table 1, when different wavelengths are set between the opposing devices, the state is normal and the communication mode is set. When the same wavelength is set, the wavelength setting operation is repeated to enter the retransmission mode. In cases other than these, one of the devices is not operating for some reason (power OFF or failure), or the transmission path is disconnected, and the operating device issues a warning and enters a standby mode.

  As described above, the transmission / reception wavelength can be automatically set between the devices by the control circuit of the optical transmission / reception device, and the automatic wavelength setting operation between the devices is infinite by introducing randomness into the control circuit. The probability of entering the loop and repeating the wavelength setting operation can be reduced.

  The present invention has been specifically described above with reference to several embodiments. However, in view of many possible embodiments to which the principle of the present invention can be applied, the embodiments described here are merely examples, It is not intended to limit the scope of the invention. For example, from an economical point of view, an application in which only the optical transmitter and the optical receiver are made into a single product and the 2 × 2 optical switch unit is configured with two passive optical components (corresponding to cross and through) can be considered. . The configuration and details of the embodiment exemplified here can be changed without departing from the spirit of the present invention. Further, the illustrative components and procedures may be changed, supplemented, or changed in order without departing from the spirit of the invention.

It is a figure which shows the conventional structural example of the wavelength division multiplexing optical communication system using two types of optical transmission / reception apparatuses. It is a figure which shows the example of the conventional structure of the wavelength division multiplexing optical communication system using one type of optical transmission / reception apparatus. It is a figure which shows the basic structural example of the optical transmitter / receiver by this invention which comprises a wavelength division multiplexing optical communication system. It is a figure which shows the structural example of the wavelength division multiplexing optical communication system using the optical transmission / reception apparatus by Example 1 of this invention. It is a figure which shows the structural example of the wavelength division multiplexing optical communication system using the optical transmission / reception apparatus by Example 2 of this invention. It is a figure which shows the structural example of the laser diode array of the optical transmission / reception apparatus by Example 2 of this invention. It is a figure which shows the structural example of the wavelength division multiplexing optical communication system using the optical transmission / reception apparatus by Example 3 of this invention. It is a figure which shows the structural example of the wavelength division multiplexing optical communication system using the optical transmission / reception apparatus by Example 4 of this invention. It is a figure which shows the structural example of the wavelength division multiplexing optical communication system using the optical transmission / reception apparatus by Example 5 of this invention. It is a figure which shows the structural example of the optical transmitter / receiver which added the control circuit which performs a wavelength setting in the basic structural example of this invention shown in FIG. FIG. 5 is a diagram illustrating a configuration example of a wavelength division multiplexing optical communication system including a control circuit that performs wavelength setting in the configuration example of the present invention illustrated in FIG. 4. It is a figure which shows notionally an example of the wavelength setting operation | movement of this invention between the optical transmitter / receivers which oppose. It is a figure which shows notionally another example of the wavelength setting operation | movement of this invention between the optical transmitter / receivers which oppose. It is a flowchart which shows an example of the detailed flow in the wavelength setting operation | movement of this invention shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Wavelength multiplexing optical communication system 110,130 Optical transmission / reception apparatus 112,132 Optical transmitter 114,134 Optical receiver 116,136 Wavelength multiplexer / demultiplexer 120 Optical transmission line 200 Wavelength multiplexing optical communication system 210,230 Optical transmission / reception apparatus 211, 212, 231 and 232 Optical transmitters 214, 215, 234 and 235 Optical receivers 216, 217, 236 and 237 Optical switches 218 and 238 Wavelength multiplexer / demultiplexer 220 Optical transmission path 310 Optical transmitter / receiver 312 Wavelength variable optical transmitter 314 Optical receiver 316 2 × 2 optical switch 318 Wavelength multiplexer / demultiplexer 400 Wavelength multiplexing optical communication system 410,430 Optical transmission / reception device 412 432 DFB laser diode 413 433 Temperature control circuit 414 434 Optical receiver 416 436 2 × 2 optical switches 418, 438 Wavelength multiplexing / demultiplexing 420 optical transmission line 500 wavelength division multiplexing optical communication system 510,530 optical transmission / reception device 512,536 laser diode array 513,533 selection circuit 514,534 optical receiver 516,536 2 × 2 optical switch 518,538 wavelength multiplexer / demultiplexer 520 Optical transmission line 610a, 610b Laser diode array 612a, 614a, 612b, 614b DFB laser diode 616a, 616b Optical coupler 617b Modulator 618a, 618b Optical amplifier 700 Wavelength multiplexing optical communication system 710, 730 Optical transmission / reception device 712, 738 Broadband light source 714 , 734 Optical receiver 716, 736 2 × 2 optical switch 718, 738 Wavelength multiplexer / demultiplexer 720 Optical transmission line 800 Wavelength multiplexing optical communication system 810, 830 Optical transceiver 812, 832 DFB laser Iode 813,833 Temperature control circuit 814,834 Optical receiver 816,836 Tunable filter 818,838 Optical circulator 820 Optical transmission line 900 Wavelength division multiplexing optical communication system 910,930 Optical transceiver 912,932 Broadband light source 914,934 Optical reception 915, 935, 916, 936 Wavelength variable filter 918, 938 Optical circulator 920 Optical transmission line 1000 Control circuit 1100 Wavelength multiplexing optical communication system 1110, 1130 Optical transmission / reception apparatus 1010, 1030 Control circuit

Claims (9)

An optical transceiver applicable to a single-core bidirectional wavelength division multiplexing optical communication system in which optical transceivers having the same configuration are connected via an optical transmission line,
An optical transmitter capable of setting an optical signal to be transmitted to one of the first and second wavelengths;
An optical receiver capable of receiving both optical signals of the first and second wavelengths;
A wavelength multiplexer / demultiplexer for multiplexing / demultiplexing the optical signals of the first and second wavelengths, wherein the first input / output port transmits the optical signal of the first wavelength to / from the optical transmission line. And a wavelength multiplexer / demultiplexer having a second input / output port that transmits the optical signal of the second wavelength to and from the optical transmission line,
A 2 × 2 optical switch capable of switching the connection state between the optical transmitter and the optical receiver and the first and second input / output ports of the wavelength multiplexer / demultiplexer to cross or through;
An optical transmission / reception characterized in that a wavelength of the optical transmitter and a connection state of the 2 × 2 optical switch are set so that an optical signal transmitted from the optical transmitter is output to the optical transmission line. apparatus. The optical transceiver according to claim 1,
A control circuit for setting a transmission wavelength and a reception wavelength with the opposing optical transmission / reception device;
The control circuit is configured to set one of the first and second wavelengths as a transmission wavelength at a random time interval, and to set the other wavelength as a reception wavelength, and at a predetermined reception wavelength. An optical transmission / reception apparatus that operates to establish communication at the set transmission wavelength and reception wavelength when an optical signal of a level of is detected. The optical transceiver according to claim 1,
A control circuit for setting a transmission wavelength and a reception wavelength with the opposing optical transmission / reception device;
The control circuit is configured to randomly select one of the first and second wavelengths at a predetermined time interval or a random time interval and set it as a transmission wavelength, and set the other wavelength as a reception wavelength. And an optical transmission / reception apparatus that operates to establish communication at the set transmission wavelength and reception wavelength when an optical signal of a predetermined level is detected at the set reception wavelength. The optical transmission / reception apparatus according to any one of claims 1 to 3 ,
The optical transmitter / receiver comprises a laser diode that can be set to one of the first and second wavelengths by temperature control. The optical transmission / reception apparatus according to any one of claims 1 to 3 ,
The optical transmitter includes: a first laser diode that outputs an optical signal of the first wavelength; and a second laser diode that outputs an optical signal of the second wavelength. Transmitter / receiver. The optical transmission / reception apparatus according to claim 5 .
The optical transmitter / receiver characterized in that the first and second laser diodes are integrated on a single chip. An optical transceiver applicable to a single-core bidirectional wavelength division multiplexing optical communication system in which optical transceivers having the same configuration are connected via an optical transmission line,
An optical transmitter including a broadband light source capable of outputting an optical signal including first and second wavelengths;
An optical receiver capable of receiving both optical signals of the first and second wavelengths;
A wavelength multiplexer / demultiplexer for multiplexing / demultiplexing the optical signals of the first and second wavelengths, wherein the optical signal of the first wavelength is selectively transmitted to and from the optical transmission line; A wavelength multiplexer / demultiplexer having an input / output port and a second input / output port that selectively transmits the optical signal of the second wavelength between the optical transmission line;
A 2 × 2 optical switch capable of switching the connection state between the optical transmitter and the optical receiver and the first and second input / output ports of the wavelength multiplexer / demultiplexer to cross or through;
The connection state of the 2 × 2 optical switch is set so that the optical signal having the first or second wavelength transmitted from the optical transmitter is output to the optical transmission line. Transmitter / receiver. The optical transmission / reception apparatus according to claim 7 .
A control circuit for setting a transmission wavelength and a reception wavelength with the opposing optical transmission / reception device;
The control circuit sets the connection state of the 2 × 2 optical switch to cross or through at random time intervals, sets one of the first and second wavelengths as a transmission wavelength, and receives the other wavelength And configured to set a wavelength, and operates to establish communication at the set transmission wavelength and reception wavelength when an optical signal of a predetermined level is detected at the set reception wavelength. Optical transmission / reception device. The optical transmission / reception apparatus according to claim 7 .
A control circuit for setting a transmission wavelength and a reception wavelength with the opposing optical transmission / reception device;
The control circuit sets the connection state of the 2 × 2 optical switch to cross or through at predetermined time intervals or at random time intervals, and randomly selects one of the first and second wavelengths for transmission. The other wavelength is set as the reception wavelength, and when an optical signal of a predetermined level is detected at the set reception wavelength, communication is performed at the set transmission wavelength and reception wavelength. An optical transceiver characterized by operating so as to establish.

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