JP3555860B2 - Optical demultiplexer and wavelength converter - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical demultiplexer and a wavelength conversion device, and is particularly effective when applied to an arrayed waveguide type diffraction grating used in an optical transmission system such as optical communication, optical switching, and optical information processing using wavelength multiplexing. Technology.
[0002]
[Prior art]
FIG. 4A is a schematic diagram showing a schematic configuration of a conventional arrayed waveguide type diffraction grating. For simplicity, a 1-input / 4-output arrayed waveguide grating used in an optical transmission system in which four wavelengths are multiplexed will be described as an example. The material is a quartz-based waveguide, or a polymer waveguide or a semiconductor waveguide.
[0003]
4A, reference numeral 401 denotes an input waveguide, 402 denotes an input slab waveguide, 403 denotes an array waveguide, 404 denotes an output slab waveguide, and 405 to 408 denote output waveguides. In the figure, when the wavelength-division multiplexed light λa, λb, λc, λd is input to the input optical waveguide 401, it is distributed by the input slab waveguide 402 and distributed at the same intensity as the array waveguide 403. Each of the distributed wavelength-division multiplexed lights has a delay difference according to the optical path length of the arrayed waveguide 403, and is input to the output slab waveguide 404 and converges.
[0004]
At this time, since the phase condition varies depending on the wavelength, an arrayed waveguide type diffraction grating is used as an optical demultiplexer by utilizing the phenomenon that different wavelengths are concentrated in the output waveguides 405 to 408.
[0005]
That is, λa is output to the output optical waveguide 405, λb is output to the output optical waveguide 406, λc is output to the output optical waveguide 407, and λd is output to the output optical waveguide 408. Although FIG. 4A shows an example of one input and four outputs, the number of input waveguides is increased to be used as a four-input four-output optical spectroscope as shown in FIG. 4B. It is also possible. The input / output characteristics of the arrayed waveguide type diffraction grating in this case are, for example, as shown in FIG.
[0006]
Next, an example in which a conventional arrayed waveguide type diffraction grating is applied to an optical transmission system will be described.
[0007]
The optical transmission system using wavelength multiplexing has been focusing on the 1.55 micron (μm) band with the development of the erupum-doped optical fiber amplifier (effective band 1530-1560 nm: collectively referred to as the 1.55 micron (μm) band). Has developed. However, with the recent development of long wavelength band optical fiber amplifiers (effective band: 1570 to 1600 nm: collectively referred to as 1.58 micron band), networks using the 1.58 micron band are also being developed. What is important here is the interconnection of networks using various wavelengths.
[0008]
In Japan, dispersion-shifted fibers that are advantageous for transmitting high-speed signals (for example, 10 Gb / s or more) have been laid for a long time. On the other hand, dispersion-shifted fibers have strong interference between wavelength-multiplexed signals, and generally use wavelength-multiplexed signals at unequal intervals. On the other hand, in Europe and the United States, wavelength-division multiplexed signals are used at regular intervals together with the installation of a dispersion fiber, and interconnection between unequally spaced and equally spaced networks is also important.
[0009]
FIG. 5 is a schematic diagram showing a schematic configuration of a conventional multi-wavelength batch conversion device for connecting a network (reference: Japanese Patent Application No. 11-65036, Kikuchi, Shibata, Ito “Multi-wavelength conversion device”). ). Here, for simplicity, a WDM system using four wavelengths is assumed, and four wavelengths of λ1, λ2, λ3, and λ4 are used as input signal light wavelengths before conversion, and output signal light wavelengths (= pump light wavelengths) after conversion are used. , Λ5, λ6, λ7, λ8. Practically, for example, the wavelengths of λ1, λ2, λ3, λ4, λ5, λ6, λ7, and λ8 are 1551 nm, 1552 nm, 1553 nm, 1554 nm, 1557 nm, 1559 nm, 1562 nm, and 1566 nm, respectively.
[0010]
In FIG. 5, reference numeral 501 denotes an input optical fiber for inputting wavelength-division multiplexed signal light of λ1 to λ4, 502 to 505 denote pump light input optical fibers for inputting λ5 to λ8 pump light, and 506 denotes a pump light input optical fiber. In the wavelength demultiplexer, for example, a 5-input / 4-output arrayed waveguide type diffraction grating using a silica-based planar type waveguide (PLC), 507 to 510 are branch waveguides for guiding a demultiplexed optical signal or Optical fibers, 511 to 514, wavelength converters, and 515, an optical multiplexer, are, for example, 4-input, 1-output arrayed waveguide type diffraction gratings by PLC. 516 is an output optical fiber, 517 to 520 are pump light sources, and 521 to 524 are optical amplifiers for amplifying the pump light.
[0011]
Here, when wavelength-multiplexed signal light of λ1, λ2, λ3, and λ4 is input to the wavelength-multiplexed signal light input optical fiber 501 and pump light of λ5, λ6, λ7, and λ8 is input to the optical fibers 502 to 505, branching occurs. Λ1 and λ5 are output to the waveguide 507, λ2 and λ6 are output to the branch waveguide 508, λ3 and λ7 are output to the branch waveguide 509, and λ4 and λ8 are output to the branch waveguide 510.
[0012]
Here, the wavelength conversion is performed in each optical conversion element by arbitrarily modulating the input signals λ1 to λ4. For example, by using a semiconductor optical amplifying element as an optical wavelength conversion element and injecting a certain optimum bias current, when the input signal light is on, the gain of the pump light is reduced, and the input signal light is turned off. At this time, the gain of the pump light is recovered. So-called mutual gain modulation occurs, and inverter-type wavelength conversion occurs. That is, the wavelength converted lights λ5, λ6, λ7, λ8 having the wavelength of the pump light and the signal information of the input signal light are generated. This is multiplexed by an optical multiplexer (arrayed waveguide type diffraction grating) 515 and output to an output optical fiber 516 to convert the equally-spaced wavelengths λ1 to λ4 into unequally-spaced wavelengths λ5 to λ8. Batch conversion becomes possible. Note that, here, only multi-wavelength batch conversion (wavelength conversion from signal light of 1551 to 1554 nm to 1557 to 1566 nm) between adjacent wavelengths has been described, but by changing the wavelength of pump light, multi-wavelength conversion to a farther wavelength is performed. Batch conversion of multiple wavelengths to batch conversion of wavelengths (for example, from 1.55 μm band to 1.58 μm band) is also possible.
[0013]
[Problems to be solved by the invention]
In the above method, the signal light is wavelength-multiplexed, whereas the pump light requires one input port for one wavelength. That is, a plurality of pump light sources 517 to 520 are used. However, in practice, rather than preparing a plurality of pump light sources, one multi-wavelength simultaneous output laser capable of simultaneously outputting multiple wavelengths (wavelength multiplexing pump light) (Reference: M. Zirngibbl, CH Joyner) , CR Doerr, LW Stulz, and HM Persby: "An 18-channel multifrequency laser", IEEE Photonics Technology Letters, Vol. 8, No. 8, p. ) Can be used as a pump light source, so that the price of the entire system can be reduced.
[0014]
When the output power of the pump light is insufficient, it is cheaper to collectively amplify the wavelength-multiplexed pump light by the optical amplifier than to amplify the output from the different pump light sources by the different optical amplifiers 521 to 524. Therefore, it is desired that the wavelength division multiplexing pump light can be demultiplexed at the same time as the wavelength demultiplexer (array waveguide type diffraction grating) 506 demultiplexes the wavelength division multiplexing signal light using the wavelength division multiplexing pump light in the system of FIG. Was.
[0015]
An object of the present invention is to provide a technique capable of demultiplexing wavelength multiplexed signal light and wavelength multiplexed pump light.
Another object of the present invention is to provide a technique capable of reducing the cost of a multi-wavelength batch conversion device.
The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.
[0016]
[Hand beat to solve the problem]
The following is a brief description of the outline of the invention disclosed in the present application.
(1) Wavelength multiplexed light is input, the wavelength multiplexed light is branched by an input side slab waveguide, and the branched wavelength multiplexed light is propagated to array waveguides having different lengths and then output slab waveguide. A signal light input waveguide, a signal light input slab waveguide, and a signal for inputting wavelength multiplexed signal light in an optical demultiplexer that demultiplexes wavelength-division multiplexed light into a plurality of waveguides by multiplexing the signals. A pump light input waveguide for inputting wavelength multiplexed pump light, a pump light input slab waveguide, and an output slab waveguide having a pump light array waveguide; Waveguides are connected to both outputs of the signal light array waveguide and the pump light array waveguide.
(2) a wavelength multiplexing signal light input waveguide for inputting a wavelength multiplexing signal light, a wavelength multiplexing pump light inputting waveguide for inputting a wavelength multiplexing pump light, the optical demultiplexer of (1), a plurality of wavelength converters, What is claimed is: 1. A wavelength converter comprising an optical multiplexer and an output optical waveguide, wherein the wavelength multiplexed signal light input waveguide and the wavelength multiplexed pump light input waveguide are the optical demultiplexer of (1). Connected, the outputs of the optical demultiplexer of (1) are respectively connected to the plurality of wavelength converters via a plurality of optical waveguides, and the respective outputs of the wavelength converter are connected to the optical multiplexer. The output of the optical multiplexer is connected to the output waveguide.
[0017]
That is, the points of the present invention include an input optical waveguide for inputting wavelength-division multiplexed light, an input slab waveguide for splitting wavelength-division-multiplexed light, and a plurality of optical waveguides for respectively guiding the split wavelength-multiplexed light. In an optical multiplexer (array waveguide type diffraction grating) including an array waveguide, an output slab waveguide connected to the array waveguide, and a plurality of output waveguides connected to the output slab waveguide, A signal light input waveguide for inputting multiplexed signal light, a signal light input slab waveguide and a signal light array waveguide having a signal light array waveguide, and a pump light input waveguide for inputting wavelength multiplexed pump light; A slab waveguide for pump light input and an array waveguide for pump light, and an output slab waveguide connected to both outputs of the signal light array waveguide and the pump light array waveguide. .
[0018]
Further, as a method of using the optical demultiplexer of the above (1), the optical demultiplexer has two input ports and a plurality of output ports, and one of the input ports is provided with a wavelength multiplexed signal light. The other port receives the wavelength multiplexed pump light, and each output port combines and outputs one wavelength of the wavelength multiplexed signal light and one wavelength of the wavelength multiplexed pump light.
[0019]
Each of the output ports is provided with a wavelength conversion element, and performs wavelength conversion by converting one wavelength of the wavelength multiplexed signal light according to the wavelength of one wavelength of the wavelength multiplexed pump light. Generates light, multiplexes the wavelength converted light generated by each wavelength conversion element using an optical multiplexer, and makes it possible to use it as a useful multi-wavelength batch conversion element by converting it to wavelength multiplexed wavelength converted light. Become.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings together with embodiments (examples) according to the present invention.
[0021]
(Embodiment 1)
FIG. 1 is a schematic diagram illustrating a schematic configuration of an optical demultiplexer according to a first embodiment of the present invention. Here, for simplicity, a WDM system using four wavelengths is assumed, and four wavelengths of λ1, λ2, λ3, and λ4 are used as wavelength multiplexed signal light, and four wavelengths of λ5, λ6, λ7, and λ8 are used as wavelength multiplexed pump light. An example of use will be described. Practically, for example, the wavelengths of λ1, λ2, λ3, λ4, λ5, λ6, λ7, and λ8 are 1551 nm, 1552 nm, 1553 nm, 1554 nm, 1557 nm, 1559 nm, 1562 nm, and 1566 nm, respectively.
[0022]
In FIG. 1, reference numeral 101 denotes a wavelength multiplexed signal light input waveguide, 102 denotes a wavelength multiplexed signal light input slab waveguide, 103 denotes a wavelength multiplexed signal light array waveguide, 104 denotes a wavelength multiplexed pump light input waveguide, 105 Is a slab waveguide for wavelength multiplexing pump light, 106 is an array waveguide for wavelength multiplexing pump light, 107 is an output slab waveguide, and 108 to 111 are output waveguides.
[0023]
In FIG. 1, when the wavelength multiplexed signal light λ1, λ2, λ3, λ4 is input to the wavelength multiplexed signal light input waveguide 101, it is distributed by the wavelength multiplexed signal light input slab waveguide 102, and The light is distributed with equal intensity to the array waveguide 103. Each of the distributed wavelength-division multiplexed lights has a delay difference according to the optical path length of the wavelength-division multiplexed signal light array waveguide 103, and is input to the output slab waveguide 107 and converges. At this time, since the phase condition differs depending on the wavelength, the wavelength-division multiplexed signal light is separated using the phenomenon that different wavelengths are concentrated in the output waveguides 108 to 111.
[0024]
On the other hand, when the wavelength multiplexing pump light λ5, λ6, λ7, λ8 is input to the wavelength multiplexing pumping light input waveguide 104, it is distributed by the wavelength multiplexing pumping light slab waveguide 105, and the wavelength multiplexing pump light array waveguide is provided. Dispensed with an intensity equal to 106. Each of the distributed wavelength-division multiplexed lights has a delay difference according to the optical path length of the wavelength-division multiplexed pump light array waveguide 106, is input to the output slab waveguide 107, and converges. At this time, since the phase condition differs depending on the wavelength, the wavelength-division multiplex pump light is separated by using the phenomenon that different wavelengths are focused on the output waveguides 108 to 111.
[0025]
Here, the positions where the respective waveguides of the wavelength-division multiplexed signal light array waveguide 103 are connected to the output slab waveguide 107, and the respective waveguides of the wavelength-division multiplexed pump light array waveguide 106 are further connected to the output slab waveguide. Position where the waveguides 107 and 111 are connected to the output slab waveguide 107, the wavelength multiplexed signal light array waveguide 103 and the wavelength multiplexed pump light array waveguide 106 By optimally designing the optical path length difference between the waveguides, λ1 and λ5 are set to the output waveguide 108, λ2 and λ6 are set to the output waveguide 109, λ3 and λ7 are set to the output waveguide 110, and λ4 and λ8 are set. It can output to each of the output waveguides 111.
[0026]
(Embodiment 2)
FIG. 2 is a schematic diagram showing a schematic configuration of a wavelength conversion device according to a second embodiment of the present invention, which is for explaining a new configuration of a multi-wavelength batch conversion device using the optical demultiplexer of the first embodiment. FIG. Here, for simplicity, a WDM system using four wavelengths is assumed, and four wavelengths of λ1, λ2, λ3, and λ4 are used as input signal light wavelengths before conversion, and output signal light wavelengths (= pump light wavelengths) after conversion are used. Four wavelengths λ5, λ6, λ7, λ8 are used. In practical use, for example, the wavelengths of λ1, λ2, λ3, λ4, λ5, λ6, λ7, and λ8 are 1551 nm, 1552 nm, 1553 nm, 1554 nm, 1557 nm, 1559 nm, 1562 nm, and 1566 nm, respectively.
[0027]
In FIG. 2, reference numeral 201 denotes a wavelength multiplexing signal light input fiber for inputting λ1 to λ4 wavelength multiplexing signal light, 202 denotes a wavelength multiplexing pump light inputting fiber for inputting λ5 to λ8 wavelength multiplexing pump light, and 206 denotes the same figure. 1, the optical demultiplexers 207 to 210 are branch waveguides or optical fibers for guiding the respective optical signals demultiplexed by the optical demultiplexer 206, and 211 to 214 are The wavelength converter 215 is an optical multiplexer, for example, a 4-input / 1-output arrayed waveguide type diffraction grating by PLC, and 216 is an output optical fiber (207 to 216 in FIG. 2 are 507 to 507 in FIG. 5). 516). Reference numeral 217 denotes a multi-wavelength simultaneous output laser that simultaneously oscillates wavelengths of λ5 to λ8, and 218 denotes an optical amplifier for amplifying pump light.
[0028]
Here, wavelength multiplexed signal light of λ1, λ2, λ3, λ4 is input to the wavelength multiplexed signal light input fiber 201, and wavelength multiplexed pump light of λ5, λ6, λ7, λ8 is input to the wavelength multiplexed pump light input fiber 202. When input, λ1 and λ5 are output to the branch waveguide 207, λ2 and λ6 are output to the branch waveguide 208, λ3 and λ7 are output to the branch waveguide 209, and λ4 and λ8 are output to the branch waveguide 210, respectively. . Here, wavelength conversion is performed in each optical conversion element by arbitrarily modulating the input signals λ1 to λ4. For example, by using a semiconductor optical amplifying element as an optical wavelength conversion element and injecting a certain optimum bias current, when the input signal light is on, the gain of the pump light is reduced, and the input signal light is turned off. At this time, the gain of the pump light is recovered. So-called mutual gain modulation occurs, and impark-type wavelength conversion occurs.
[0029]
That is, the wavelength converted lights λ5, λ6, λ7, λ8 having the wavelength of the pump light and the signal information of the input signal light are generated. This is multiplexed by an optical multiplexer (array waveguide type diffraction grating) 215 and output to an output optical fiber 216 to convert the equally-spaced wavelengths λ1 to λ4 into unequally-spaced wavelengths λ5 to λ8. Batch conversion becomes possible.
[0030]
Note that, here, only multi-wavelength batch conversion (wavelength conversion from signal light of 1551 to 1554 nm to 1557 to 1566 nm) between adjacent wavelengths has been described, but by changing the wavelength of pump light, multi-wavelength conversion to a farther wavelength is performed. Multi-wavelength batch conversion to wavelength batch conversion (for example, from 1.55 μm band to 1.58 μm band) is also possible.
[0031]
(Embodiment 3)
FIG. 3 is a schematic diagram for explaining a case where a multi-wavelength simultaneous output laser is used as a light source in the wavelength converter according to the third embodiment of the present invention, where 301 is a semiconductor laser having a wavelength of 1.48 μm, and 302 is light. An isolator, 303 is an optical fiber doped with erpium, and 304 to 307 are gratings (waveguide type diffraction gratings) formed in the optical fiber 303, whose reflection Bragg wavelengths correspond to λ5, λ6, λ7, λ8, respectively. , 308 are output optical fibers.
[0032]
In FIG. 3, reflections of λ5, λ6, λ7, λ8 are repeated at a part of the optical fiber 303 pumped by the semiconductor laser 301, that is, gratings (waveguide type diffraction gratings) 304 to 307, and the gratings 304 to 307 are repeated. Functions as a distributed reflection fiber laser. The wavelengths λ5 to λ8 are multiplexed, respectively, and can be output by the output optical fiber 308.
[0033]
As described above, the invention made by the inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and can be variously modified without departing from the gist of the invention. Of course.
[0034]
【The invention's effect】
As described above, according to the present invention, it is possible to demultiplex a wavelength multiplexed signal light and a wavelength multiplexed pump light. Thereby, for example, instead of using a plurality of pump light sources and a plurality of optical amplifiers in the multi-wavelength batch conversion device, by using one multi-wavelength simultaneous output laser and one optical amplifier, the entire multi-wavelength batch conversion device can be realized. Costs can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating a schematic configuration of an optical multiplexer according to a first embodiment of the present invention.
FIG. 2 is a schematic diagram illustrating a schematic configuration of a wavelength conversion device according to a second embodiment of the present invention.
FIG. 3 is a schematic diagram illustrating a schematic configuration of a multi-wavelength simultaneous output laser of a wavelength converter according to a third embodiment of the present invention.
FIG. 4 is a schematic diagram showing a schematic configuration of a conventional arrayed waveguide type diffraction grating.
FIG. 5 is a schematic diagram showing a schematic configuration of a conventional multi-wavelength batch conversion device for connecting a network.
[Explanation of symbols]
101: Wavelength multiplexed signal light input waveguide, 102: Wavelength multiplexed signal light input slab waveguide, 103: Wavelength multiplexed signal light array waveguide, 104: Wavelength multiplexed pump light input waveguide, 105: Wavelength multiplexing Slab waveguide for pump light, 106: arrayed waveguide for wavelength multiplexed pump light, 107: slab waveguide for output, 108 to 111: waveguide for output, 201: fiber for inputting wavelength multiplexed signal light, 202: wavelength multiplexed pump Optical input fiber, 206: optical demultiplexer, 207 to 210: demultiplexing waveguide or optical fiber, 211 to 214: wavelength converter, 215: optical multiplexer (arrayed waveguide type diffraction grating), 216: output light Fiber, 217: Multi-wavelength simultaneous output laser, 218: Optical amplifier, 301: Semiconductor laser, 302: Optical isolator, 303: Erpium-doped fiber , 304 to 307: grating (waveguide type diffraction grating), 308: output optical fiber, 401: input optical waveguide, 402: input slab waveguide, 403: array waveguide, 404: output slab waveguide, 405 to 408: output optical waveguide, 501: input optical fiber, 502 to 505: pump light input optical fiber, 506: wavelength demultiplexer (arrayed waveguide type diffraction grating), 507 to 510: branch waveguide or Optical fibers, 511 to 514: wavelength converter, 515: optical multiplexer (array waveguide type diffraction grating), 516: output optical fiber, 517 to 520: pump light source, 521 to 524: optical amplifier.

Claims (2)

Wavelength multiplexed light is input, the wavelength multiplexed light is branched by an input side slab waveguide, and the branched wavelength multiplexed light is propagated to array waveguides having different lengths, and then multiplexed by an output slab waveguide. And a signal light input waveguide for inputting a wavelength multiplexed signal light, a signal light input slab waveguide, and a signal light array. Having a waveguide, and having a pump light input waveguide for inputting wavelength multiplexed pump light, a pump light input slab waveguide, and a pump light array waveguide, wherein the output slab waveguide is An optical demultiplexer characterized by being connected to both outputs of a signal light array waveguide and a pump light array waveguide. 2. A wavelength multiplexing signal light input waveguide for inputting a wavelength multiplexing signal light, a wavelength multiplexing pump light inputting waveguide for inputting a wavelength multiplexing pump light, the optical demultiplexer of claim 1, a plurality of wavelength converters, and an optical multiplexer. And a wavelength converter including an output optical waveguide, wherein the wavelength multiplexed signal light input waveguide and the wavelength multiplexed pump light input waveguide are connected to the optical demultiplexer of claim 1, 2. The output of the optical demultiplexer of claim 1 is connected to the plurality of wavelength converters via a plurality of optical waveguides, and the respective outputs of the wavelength converter are connected to the optical multiplexer. An output of a wavelength converter is connected to the output waveguide.

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