JP2738492B2 - Optical switch module - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical switching type module connection device (optical IMC device) for connecting a number of modules constituting a communication system or the like and selectively switching between the modules as necessary. The present invention relates to an optical switch module which is suitable for application to the like.

[0002]

2. Description of the Related Art Generally, a communication system or the like is composed of a large number of modules. In recent years, these modules have been increasingly connected by an optical interface. On the other hand, when a specific module fails, it is necessary to promptly switch to a spare module.
This switching operation is performed in an optical interface, and an optical IMC device is used as the optical interface. In this optical IMC device, a direct switching operation is performed by an optical switch module.

[0003] As an optical IMC switch module, for example, T. Ito et al., GLOBELOM '92, PP.
inter-module connector using silica-based optical
switches "are known.
The switch module for C is shown in FIGS.

The switch module for optical IMC is an optical switch module in which an 8-input / 8-output crossbar type optical switch using a quartz optical waveguide technology is mounted on a printed circuit board together with a switch driving circuit. This switch has 64 2 × 2 switch elements 1 as shown in FIG.
[Cross state] depending on the heater current
And [Bar state] are switched. Also,
This switch has an 8-input port, an 8-output port, and an idle port 17 that is used for adjusting the switch and is not used in actual use.

FIGS. 5 and 6 show the configuration of the 2 × 2 switch element 1. FIG. The switch element 1 uses a symmetric Mach-Zehnder interferometer using a glass waveguide, and performs a switch operation by using an effect that can change the refractive index by applying heat (thermo-optical effect). Specifically, the 2 × 2 switch element 1 includes two waveguides 3 and 4 on the incident side and a first 3 dB for multiplexing and demultiplexing light from each of the waveguides 3 and 4 on the substrate 2. Coupler 5
And two arm portions 6 and 7 that are bifurcated, thin-film heaters 8 and 9 provided in each arm portion 6 and 7, respectively, and a second device that multiplexes and demultiplexes light from each arm portion 6 and 7. 3 dB coupler 10 and two waveguides 11 and 12 on the emission side. 2 × 2 switch element 1 of this configuration
In the above, by flowing a current to one of the thin film heaters 8 and 9 and adjusting the current, the temperature difference between the arms 6 and 7 is controlled to change the state of the interferometer, and the [cross state] is changed. Switches to [Bar state].

FIG. 7 shows a waveguide layout of an 8 × 8 switch matrix using the 2 × 2 switch element 1. At the input / output terminals to the switch, single-mode optical fibers 14 and 15 with an 8-core and 16-core (two sets of 8-core) with an SC connector at the end are attached, respectively. 2x2
In the state where the switch element 1 is laid out in this way, heat radiation fins are attached to the back surface, and are housed in the center of a package (not shown) which is a mounting board for each component. Further, 64 variable resistor groups for adjusting the heater current of each 2 × 2 switch element 1 and an on-board power supply are mounted on the periphery thereof.

FIG. 8 is a functional block diagram of a circuit for controlling the thin film heaters 8 and 9. The optical IMC switch module is provided with circuits for adjusting the current flowing to the thin film heaters 8 and 9 of each 2 × 2 switch element 1. This circuit is provided with 64 sets corresponding to each 2 × 2 switch element 1, and mainly includes two variable resistors 21 and 22 and a transistor 23 for controlling a current flowing to the first variable resistor 21. It is composed of
Although 64 sets of this circuit are provided, only one set is shown in the figure. Either one of the two thin film heaters 8 and 9 is selected, and only one of the heaters is controlled. Further, the second transistor 25 in the figure is provided to monitor whether the operation of the first transistor 23 is normal.

As a specific operation of this current adjusting circuit, when a “1” signal is input from an input terminal 24, the first transistor 23 is turned on, and the current adjusted mainly by the first variable resistor 21. Flows into the thin film heater 8, and the 2 × 2 switch element 1 is set to the “bar state”. This current is adjusted so that light leakage to the cross port in the [bar state] is minimized.

When a "0" signal is input from the input terminal 24, the first transistor 23 is turned off, and the current adjusted by the second variable resistor 22 flows through the thin film heater 10 to cause the 2 × 2 switch element to be turned off. 1 becomes the [cross state].
This current is adjusted so that light leakage to the bar port in the [cross state] is minimized.

The variable resistors 21 and 22, the transistor 23, and the like are simultaneously incorporated in the manufacturing stage of the optical IMC switch module, and are individually adjusted by an operator after the completion of the optical IMC switch module. In particular,
With the optical signal actually passed through the optical fiber, input terminal 2
The operator manually adjusts the first variable resistor 21 by inputting a "1" signal from 4, and similarly adjusts the second variable resistor 22 by inputting a "0" signal.

[0011]

By the way, in the switch module for optical IMC having the above configuration, two variable resistors 2 are used.
1 and 22 indicate the number of mounted 2 × 2 switch elements 1 (64
), And the individual variable resistors 21 and 22 themselves are large in size, so that there is a problem that the entire device becomes large.

Further, since the adjustment of each of the variable resistors 21 and 22 is manually performed one by one by an operator, it takes time to adjust all the variable resistors 21 and 22 and the productivity is poor. There is.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and provides an optical switch module which is excellent in productivity and which can easily downsize the device and adjust the power of the variable resistor in a short time. The purpose is to do.

[0014]

According to a first aspect of the present invention, a plurality of optical paths on an incident side and a plurality of optical paths on an output side are selectively used by utilizing a characteristic change due to a difference in temperature. An optical waveguide substrate to be switched and connected to a heating element for adjusting the temperature by adjusting the power provided on the optical waveguide substrate to change the amount of heat generated, a circuit board on which the optical waveguide substrate is mounted, and Variable resistor for adjusting power of heating element
And an electric circuit portion including the variable resistor, wherein the variable resistor is formed of a thick film resistor, and the electric circuit portion including the thick film variable resistor has the optical waveguide substrate mounted on a surface thereof. Formed on the back surface of the circuit board ,
At least, the thick film-shaped variable resistor is exposed to the outside
As described above, the heat radiation fins are provided on the back surface via spaces .

Further, the second invention is characterized in that the power of the heating element is adjusted by changing the resistance value of the thick film variable resistor by laser trimming.

[0016]

According to the first aspect of the present invention, the variable resistor is formed of a thick-film resistor so that the variable resistor can be reduced. Further , an electric circuit portion including the variable resistor is provided on the back surface of the circuit board. By forming, the whole can be reduced in size. In addition, a space is provided on the back side where the electric circuit
To provide efficient heat radiation.
Can be.

According to the second aspect of the present invention, the power can be adjusted easily and in a short time by adjusting the power of the heating element by gradually changing the resistance value of the variable resistor by laser trimming.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

The basic function of the optical switch module of this embodiment is almost the same as that of the above-mentioned conventional optical IMC switch module. Here, an example of an 8-input / 8-output crossbar optical switch will be described. I do. Also,
The same parts as those of the conventional optical switch module are denoted by the same reference numerals, and description thereof will be omitted.

FIGS. 1 and 2 show the overall configuration of this optical switch module. Reference numeral 31 in the figure denotes a ceramic multilayer substrate. On the surface (upper surface) of the ceramic multilayer substrate 31, a quartz optical waveguide substrate 32 having the same configuration as the conventional waveguide layout shown in FIG. 7 is mounted. A protective cap 33 is provided on the quartz optical waveguide substrate 32. A radiating fin 36 is attached to the back surface of the ceramic multilayer substrate 31 via a spacer 35. The radiating fins 36 release heat generated by a thin film heater 51 described later incorporated in the quartz optical waveguide substrate 32 to the outside.

In the figure, reference numeral 41 denotes a fiber fixture for supporting and fixing the input side optical ribbon fiber 42 and the output side optical ribbon fiber 43 connected to the quartz optical waveguide substrate 32, respectively.

Here, a control circuit of the thin film heater mounted on the 2 × 2 switch element 1 (see FIG. 5) incorporated in the quartz optical waveguide substrate 32 will be described with reference to FIG.

In the figure, reference numeral 51 denotes a 2 × 2 switch element 1
This is a thin-film heater incorporated in the device. Although only one thin film heater 51 is shown here, even if this thin film heater 51 is provided only in one of the arm portions 6 and 7 (see FIG. 5), two thin film heaters 51 are provided in parallel as in the conventional case. Crab may be switched.

The thin-film heater 51 includes a transistor 52
Grounded through. Further, a trimmable resistor 53 and a fixed resistor 54, which are variable resistors, are connected in parallel with the transistor 52. The trimmable resistor 53 and the fixed resistor 54 are each formed in a thick film shape, and are printed directly on the back surface of the ceramic multilayer substrate 31 one by one or attached as chip components (see FIGS. 1 and 2).

The reason why only one trimmable resistor 53 is provided is as follows. Conventionally, two variable resistors 21 and 22
Is provided to adjust the current flowing through the thin film heaters 8 and 9 in each of the [bar state] and the [cross state]. On the other hand, the present inventor has found that in the circuit having the above configuration, the light leakage in the [cross state] affects the output port as crosstalk, but the light leakage in the [bar state] passes through the idle port 17 in FIG. Focusing on the influence, the resistance value is individually adjusted only for the [cross state], and based on this, only one trimmable resistor 53 is provided. The fixed resistors 55 and 56 are built in the transistor 52.

However, when the requirements for the optical switch module are severe, or when the light from the idle port 17 in FIG. 4 needs to be extracted as a signal depending on the system configuration, as shown in FIG.
It may be necessary to provide a number of trimmable resistors.

The thin-film heater 51 and the heater control circuit having the above-described configuration have 6 in accordance with the number of 2 × 2 switch elements 1.
Four sets are provided.

The transistor 52, the trimmable resistor 53, and the fixed resistor 54 are provided on the back surface of the ceramic multilayer substrate 31, as shown in FIGS. The trimmable resistor 53 and the fixed resistor 54 are provided on both sides (both right and left sides in the figure) of the radiation fin 36 on the back surface of the ceramic multilayer substrate 31. Specifically, a total of 64 sets are provided in two rows on both sides of the radiation fins 36. In this arrangement, a trimmable resistor 53 is provided outside and a fixed resistor 54 is provided inside. Further, 64 transistors 52 are incorporated inside the radiation fin 36.

In the optical switch module configured as described above, the adjustment of the trimmable resistor 53 is performed at the time of assembling the optical switch module. Specifically, the quartz optical waveguide substrate 32 is mounted on the front surface of the ceramic multilayer substrate 31, the transistor 52, the trimmable resistor 53, and the fixed resistor 54 are mounted on the rear surface.
And before attaching the fiber fixture 41, each 2
Light is propagated to the × 2 switch elements 1 to adjust the trimmable resistors 53 of the corresponding heater control circuits by a laser trimming method. This laser trimming is performed automatically during the manufacturing process. Alternatively, the optical switch module may be assembled after individually adjusting the resistance values of the trimmable resistors 53 by the laser trimming method based on the data of the quartz-based optical waveguide substrate 32 measured separately in advance. In this case, as compared with adjusting the light power while measuring the optical power by propagating the light as described above,
Further, the adjustment work can be completed in a shorter time.

The specific operation of the optical switch module configured as described above is almost the same as that of the above-described conventional optical switch module. That is, when a “1” signal is input from the input terminal 57, the transistor 52 is turned on,
A constant current flows through the thin-film heater 51, and the 2 × 2 switch element 1 enters the “bar state”. When a "0" signal is input from the input terminal 57, the transistor 52 is turned off, the current adjusted by the trimmable resistor 53 flows to the thin film heater 51, and the 2 × 2 switch element 1 enters the “cross state”.

As described above, the trimmable resistor 53 is formed in a thick film shape and is automatically adjusted in the manufacturing process by the laser trimming method so as to correspond to each switch element 1, so that the power of the trimmable resistor 53 is adjusted. The adjustment can be performed in a short time. As a result,
Productivity is greatly improved.

Further, since the trimmable resistor 53 is formed in a thick film shape, the variable resistor portion in the mounted state can be significantly reduced in size, and the optical switch module can be reduced in size.

Although the operation state of the first transistor 21 is monitored by providing the second transistor 25 in the prior art, it is not provided in the present embodiment. It is.

In the above embodiment, an 8-input 8-output crossbar optical switch has been described as an example. However, it goes without saying that a crossbar optical switch having a configuration other than 8-input 8-output may be used.

[0035]

According to the present invention as described in detail above, the following effects can be obtained.

(1) Since the thick film-shaped variable resistor is automatically adjusted by the laser trimming method in correspondence with each switch element, power adjustment of the variable resistor can be performed in a short time, and productivity can be improved. Significantly improved.

(2) Since the variable resistor is constituted by a thick film resistor and provided on the circuit board, the variable resistor portion in the mounted state can be significantly reduced in size, and as a result, the overall device can be reduced in size. can do.

[Brief description of the drawings]

FIG. 1 is a front view showing an optical switch module according to the present invention.

FIG. 2 is a rear view of the optical switch module shown in FIG.

FIG. 3 is a functional block diagram showing a control circuit of the thin film heater according to the present invention.

FIG. 4 is a diagram showing a waveguide layout of an 8 × 8 switch matrix.

FIG. 5 is a plan view showing a configuration of a 2 × 2 switch element.

FIG. 6 is a schematic configuration diagram showing an interferometer portion of a 2 × 2 switch element.

FIG. 7 is a configuration diagram showing a waveguide layout of an 8 × 8 switch matrix.

FIG. 8 is a functional block diagram showing a control circuit of a conventional thin film heater.

[Explanation of symbols]

Reference numeral 31 denotes a ceramic multilayer substrate, 32 denotes a quartz optical waveguide substrate, 36 denotes radiation fins, 41 denotes a fiber fixing tool, 42,
43 ... optical ribbon fiber, 52 ... transistor, 53 ...
Trimmable resistance, 54 ... fixed resistance.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Kiyoshi Kurosawa, Inventor 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (72) Inventor Toshiyuki Kawashima 1-7-112 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (72) Inventor Akira Himeno 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Kenichi Yukimatsu 1-16-1 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Ryo Nagase, Inventor Ryo 1-6, Uchisaiwai-cho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Masayuki Okuno 1-1-6, Uchisaiwai-cho, Chiyoda-ku, Tokyo Japan Nippon Telegraph and Telephone Corporation (72) Kuniharu Kato 1-6-1, Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Inventor Masao Kawachi Tokyo 1-6, Uchisaiwaicho, Chiyoda-ku Nippon Telegraph and Telephone Corporation (56) References JP-A-59-23303 (JP, A) JP-A-60-68329 (JP, A) JP-A-2-264823 (JP) , A)

Claims (2)

(57) [Claims] An optical waveguide substrate for selectively switching and connecting a plurality of optical paths on an incident side and a plurality of optical paths on an output side by utilizing a characteristic change due to a temperature difference, and a power provided on the optical waveguide substrate. A heating element for adjusting the temperature by adjusting the heat generation amount, a circuit board on which the optical waveguide substrate is mounted, and a variable resistor for adjusting the power of the heating element.
An optical switch module having an electric circuit section , wherein the variable resistor is formed of a thick-film-shaped resistor, and the electric circuit section including the thick-film-shaped variable resistor has the optical waveguide substrate mounted on a surface thereof. formed on the back surface of the substrate, and a small
So that the thick variable resistor is exposed to the outside
An optical switch module, wherein a radiation fin is provided on the back surface via a space . 2. The optical switch module according to claim 1, wherein the power of the heating element is adjusted by changing the resistance of the thick film variable resistor by laser trimming.