JPH0720331A - Optical switch module - Google Patents

Abstract

(57) [Summary] [Purpose] To improve productivity by downsizing the device and enabling easy adjustment in a short time. An optical waveguide substrate 3 for selectively switching and connecting a plurality of optical paths on an incident side and a plurality of optical paths on an outgoing side by changing temperature.
2, a thin film heater 51 provided on the substrate 32 to adjust the electric power to change the amount of heat generation to adjust the temperature, a ceramic multilayer substrate 31 on the surface of which the substrate 32 is mounted,
An optical switch module having a trimmable resistor 53 for adjusting the electric power of the thin film heater 51. The resistor 53 is formed of a thick film resistor, and the resistor 53 is formed on the back surface of the multilayer substrate 31. The resistance of the resistor 53 is changed by laser trimming to adjust the power of the thin film heater 51. As a result, the overall size of the thin film heater 5 is reduced.
It is possible to simplify the power adjustment of No. 1 and shorten the time.

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 inter-module connection device (optical IMC device) for connecting a large number of modules constituting a communication system or the like, and selectively switching-connecting these modules as required. The present invention relates to an optical switch module that is suitable for application to the like.

[0002]

2. Description of the Related Art Generally, a communication system or the like is composed of many modules. In recent years, these modules are 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 the optical interface, and an optical IMC device is used as this optical interface. In this optical IMC device, the direct switching operation is performed by the optical switch module.

An example of the optical IMC switch module is GLOBELOM'92, PP.187-191 "Photonic by T. Ito et al.
inter-module connector using silica-based optical
The ones described in "Switches" are known.
The switch module for C is shown in FIGS.

The optical IMC switch module is an optical switch module in which an eight-input eight-output crossbar type optical switch using a silica optical waveguide technology is mounted on a printed circuit board together with a switch drive circuit. This switch has 64 2 × 2 switch elements 1 as shown in FIG.
The heater current is used to cross each other [cross state]
And [Bar status] are switched. Also,
In addition to 8 input ports and 8 output ports, this switch has an idle port 17 which is used for adjusting the switch and is not used in actual use.

5 and 6 show the structure of the 2 × 2 switch element 1. This switch element 1 uses a symmetric Mach-Zehnder interferometer with a glass waveguide, and performs a switch operation by utilizing the effect of changing the refractive index thereof by applying heat (thermo-optical effect). Specifically, the 2 × 2 switch element 1 includes, on a substrate 2, two waveguides 3 and 4 on the incident side and a first 3 dB that multiplexes and demultiplexes the light from each of the waveguides 3 and 4. Coupler 5
And two arm portions 6 and 7 that are bifurcated, thin film heaters 8 and 9 provided in the arm portions 6 and 7, respectively, and a second that multiplexes and demultiplexes light from the arm portions 6 and 7. 3 dB coupler 10 and two waveguides 11 and 12 on the output side. 2x2 switch element 1 with this configuration
In, the electric current is passed through either of the thin film heaters 8 and 9 and the electric current is adjusted to control the temperature difference between the arm portions 6 and 7 to change the state of the interferometer. Switch between [Bar status].

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

FIG. 8 shows 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 currents flowing to the thin film heaters 8 and 9 of the 2 × 2 switch elements 1, respectively. This circuit is provided in 64 sets corresponding to each 2 × 2 switch element 1, and mainly includes two variable resistors 21 and 22 and a transistor 23 that controls a current flowing to the first variable resistor 21. It consists of
Although 64 sets of this circuit are provided, only one set is shown in the figure. Further, one of the two thin film heaters 8 and 9 is selected and only one heater is controlled. Further, the second transistor 25 in the figure is provided to monitor whether or not the operation of the first transistor 23 is normal.

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

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

[0011]

By the way, in the optical IMC switch module having the above-mentioned structure, two variable resistors 2 are provided.
1 and 22 are the number of mounted 2 × 2 switch elements 1 (64
There are 64 sets corresponding to each number, and since the individual variable resistors 21 and 22 themselves are also large, there is a problem that the size of the entire apparatus becomes large.

Further, since each operator manually adjusts the variable resistors 21 and 22, it takes time to adjust all the variable resistors 21 and 22 and the productivity is poor. There is.

The present invention has been made in view of the above-mentioned problems, and provides an optical switch module excellent in productivity, which enables downsizing of a device and power adjustment of a variable resistor to be easily performed in a short time. The purpose is to do.

[0014]

In order to solve the above-mentioned problems, a first aspect of the present invention selectively uses a plurality of optical paths on the incident side and a plurality of optical paths on the outgoing side by utilizing a characteristic change due to a difference in temperature. An optical waveguide substrate that is switched and connected to the optical waveguide substrate, a heating element that is provided on the optical waveguide substrate and that adjusts the temperature by changing the amount of heat generation, the circuit substrate on which the optical waveguide substrate is mounted, and the heat generation. In the optical switch module having a variable resistor for adjusting body power, the variable resistor is formed of a thick film resistor, and the thick film variable resistor has the optical waveguide substrate mounted on one side surface thereof. It is characterized in that it is formed on the other side surface of the circuit board.

The second invention is characterized in that the electric resistance 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 resistance can be reduced by forming the variable resistance with the thick film resistor, and by forming the variable resistance on the other side surface of the circuit board, The whole can be miniaturized.

According to the second aspect of the invention, the resistance of the variable resistor is gradually changed by laser trimming to adjust the electric power of the heating element, so that the adjustment can be performed easily and in a short time.

[0018]

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

The basic function of the optical switch module of the present embodiment is almost the same as that of the conventional optical IMC switch module described above, and here also, an explanation will be given by taking as an example the one configured as an 8-input 8-output crossbar type optical switch. To do. Also,
The same parts as those of the conventional optical switch module are designated by the same reference numerals and the description thereof will be omitted.

The overall structure of this optical switch module is shown in FIGS. Reference numeral 31 in the figure is a ceramic multilayer substrate. On the surface (upper side surface) of this ceramic multilayer substrate 31, a silica-based 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. Radiating fins 36 are attached to the back surface of the ceramic multilayer substrate 31 via spacers 35. The heat radiation fins 36 release heat generated by a thin film heater 51, which will be described later, incorporated in the quartz optical waveguide substrate 32 to the outside.

Reference numeral 41 in the figure denotes a fiber fixing tool for supporting and fixing the optical ribbon fiber 42 on the input side and the optical ribbon fiber 43 on the output side, which are connected to the quartz optical waveguide substrate 32.

The 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.

Reference numeral 51 in the figure is a 2 × 2 switch element 1.
Is a thin film heater incorporated in the. Although only one thin film heater 51 is shown here, two thin film heaters 51 may be provided in parallel on one of the arm portions 6 and 7 (see FIG. 5) as in the conventional case. Alternatively, it may be switched to.

The thin film heater 51 is composed of a transistor 52.
Is 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 one by one directly on the back surface of the ceramic multilayer substrate 31 or attached as chip parts (see FIGS. 1 and 2).

The reason for providing only one trimmable resistor 53 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, in the inventor of the present invention, the leaked light in the [cross state] affects the output port as crosstalk in the circuit having the above configuration, but the leaked light in the [bar state] is emitted to the idle port 17 in FIG. Focusing on the fact that there is no effect, 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 strict, or when it is necessary to take out the light from the idle port 17 in FIG. 4 as a signal depending on the system configuration, as shown in FIG.
It may be necessary to provide a single trimmable resistor.

The thin-film heater 51 and the heater control circuit having the above-mentioned configuration have six switches 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 (left and right sides in the drawing) of the heat 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 fin 36. In this arrangement, a trimmable resistor 53 is provided on the outside and a fixed resistor 54 is provided on the inside. Further, 64 transistors 52 are incorporated inside the radiation fin 36.

In the optical switch module configured as described above, the trimmable resistor 53 is adjusted when the optical switch module is assembled. Specifically, the quartz optical waveguide substrate 32 is mounted on the front surface of the ceramic multilayer substrate 31, and the transistor 52, the trimmable resistor 53, and the fixed resistor 54 are mounted on the rear surface thereof, respectively, and the heat radiation fin 36
And 2 in the state before attaching the fiber fixing tool 41.
Light is propagated to the × 2 switch element 1 and the trimmable resistors 53 of the corresponding heater control circuits are adjusted by the laser trimming method. This laser trimming is automatically performed in the manufacturing process. Alternatively, the optical switch module may be assembled after the resistance value of the trimmable resistor 53 is individually adjusted by the laser trimming method based on the data of the silica-based optical waveguide substrate 32 measured in advance alone. In this case, as compared with adjusting while propagating light and measuring the optical power as described above,
It is also possible to complete the adjustment work in a shorter time.

The specific operation of the optical switch module configured as described above is almost the same as that of the conventional optical switch module described above. That is, when the "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]. Further, when the "0" signal is input from the input terminal 57, the transistor 52 is turned off, the current adjusted by the trimmable resistor 53 flows into the thin film heater 51, and the 2 × 2 switch element 1 is in the [cross state].

As described above, since the trimmable resistor 53 is formed in a thick film shape and is automatically adjusted in the manufacturing process by the laser trimming method in correspondence with each switch element 1, the power of the trimmable resistor 53 is adjusted. 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 resistance portion in the mounted state can be remarkably downsized, and the optical switch module can be downsized.

In the prior art, the second transistor 25 is provided to monitor the operating state of the first transistor 21, whereas this embodiment does not provide it, but this monitor is optional. Is.

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

[0035]

As described in detail above, the present invention has the following effects.

(1) Since the thick film variable resistor is automatically adjusted by the laser trimming method in correspondence with each switch element, it is possible to adjust the power of the variable resistor in a short time, and the productivity is improved. Greatly improved.

(2) Since the variable resistor is composed of a thick film resistor and provided on the circuit board, the variable resistor portion in the mounted state can be significantly downsized, and as a result, the entire device can be downsized. can do.

[Brief description of 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 a 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]

31 ... Ceramic multilayer substrate, 32 ... Quartz optical waveguide substrate, 36 ... Radiating fins, 41 ... Fiber fixture, 42,
43 ... Optical ribbon fiber, 52 ... Transistor, 53 ...
Trimmable resistor, 54 ... Fixed resistor.

 ─────────────────────────────────────────────────── ─── Continued front page (72) Kiyoshi Kurosawa Kiyoshi Kurosawa 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (72) Toshiyuki Kawashima 1-17-1 Toranomon, Minato-ku, Tokyo Oki Denki Kogyo Co., Ltd. (72) Inventor Akira Himeno 1-1-6 Uchiyuki-cho, Chiyoda-ku, Tokyo Japan Telegraph and Telephone Corporation (72) Inventor Kenichi Gyomatsu 1-1-6 Uchiyuki-cho, Chiyoda-ku, Tokyo Japan This telegraph telephone company (72) Inventor Ryo Nagase 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Japan Telegraph telephone company (72) Inventor Masayuki Okuno 1-1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Japan Telegraph and Telephone Corporation (72) Inventor Kuniharu Kato 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Inventor Masao Kawachi Higashi Chiyoda-ku, Uchisaiwaicho chome No. 1 No. 6 Date. This Telegraph and Telephone in the Corporation

Claims (2)

[Claims] 1. 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 outgoing side by utilizing a characteristic change due to a difference in temperature, and an electric power provided on the optical waveguide board. An optical switch module comprising a heating element for adjusting the temperature by adjusting the amount of heat generation, a circuit board on which the optical waveguide substrate is mounted, and a variable resistor for adjusting the power of the heating element. The optical switch module is characterized in that the resistor is composed of a thick film resistor, and the thick film variable resistor is formed on the other side surface of the circuit board on which the optical waveguide substrate is mounted on one side surface. 2. The optical switch module according to claim 1, wherein the thick film variable resistor adjusts the electric power of the heating element by changing its resistance value by laser trimming.