JPH06244504A - Optical module - Google Patents

Abstract

PURPOSE:To provide an optical module which can output a parallel electric signal from a serial light signal or a serial light signal from a parallel electric signal and which can be realized at a low cost by a simple constitution without requiring a shield plate, wave absorber, etc. CONSTITUTION:The optical module is a light-transmitting module equipped with a package 10 containing a laser diode 16, laser driver 17 and multiplexing circuit 18 and with a terminal for connecting an optical fiber cable 11 provided in the package 10, terminal 13 for inputting a parallel eledtric signal and terminal 12 for inputting a clock signal. The package 10 is formed into a rectangular parallelopiped, which is long in the direction of the clock signal being transmitted, and the length taken in the direction perpendicularly intersecting to the longitudinal direction of the package 10 is set shorter than 1/2 of a wavelength corresponding to the fundamental frequency component of the clock signal so that the cavity resonance in the package is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical module used for transmitting or receiving an optical signal, and more particularly to a function of multiplexing parallel electric signals and converting them into serial optical signals or converting serial optical signals into parallel electric signals. The present invention relates to an optical module having.

[0002]

2. Description of the Related Art In recent years, an optical module in which an optical semiconductor element and an optical component are housed in the same package has been used as an apparatus for transmitting or receiving an optical signal. In Figure 4,
An example of an optical transmission module using a laser diode as an optical semiconductor element will be shown. A fiber cable 41 for optical output is provided on one end side in the longitudinal direction of the package 40, and an input terminal 42 for an electric signal is provided on the opposite side. A plurality of electric terminals 43 are provided on the side surface in the longitudinal direction of the package. This module for optical transmission. It has a function of inputting one electric signal and outputting one optical signal,
The terminal 43 extending from the side surface in the longitudinal direction of the package is used for power supply or ground potential.

In the optical transmission module shown in FIG. 4, the laser diode is simply connected to the electrode terminal inside the package. Therefore, in order to emit light from the laser diode, a device capable of inputting an electric signal having a large current amplitude at a high speed outside the package is required. Further, when the function of converting a parallel signal having a low speed and a wide data width into a high speed serial signal is used, it is necessary to adjust the wiring of the high speed signal and the timing of the data processing between each device outside the package. When the signal has a transmission rate of several Gbit / s, the impedance of the signal line must be matched to prevent the signal from deteriorating, and the members used for the wiring must be examined to prevent the signal from being reflected at the terminals. As a result, handling during wiring was difficult.
Further, with respect to each device part, signal crosstalk may occur in the device, and signal resonance may occur inside the envelope that surrounds the device, which may prevent normal operation of the signal.

As a conventional example of the structure of a module for receiving light, a combination of a semiconductor light receiving element and a signal amplifier IC
Some are built into one package. This optical receiving module inputs one optical signal and outputs one electric signal, and has a serial-parallel conversion function outside the package when a parallel signal is taken out from one serial signal. Connect the device. Therefore, also in this case, it is necessary to carefully examine the members for handling the high-speed signal line and pay close attention to the work, and it is also necessary to adjust the timing between the devices.

Further, an optical signal input / output device having a function of multiplexing electric signals conventionally has a board as a base, and has semiconductor integrated circuits packaged in a plurality of packages on the board. Therefore, wirings for connecting the semiconductor integrated circuits are required inside the packages, and further complicated wirings on the board for connecting the packages and a device for adjusting the phase between the packages are required. Therefore,
The board requires a large area, and a large-scale case for connecting and storing a plurality of boards has been practically necessary.

In the case of a module in which such a large-scale optical signal input / output device and an electrical signal multiplexing device are combined, the inner wall of the envelope and the signal of the module of various scales provided as the signals to be handled become faster Resonance is likely to occur, and it was necessary to provide a shield plate or an electromagnetic wave absorber inside the envelope.

[0007]

As described above, conventionally, by using the optical module having only the photoelectric conversion function inside the package, parallel electrical signals having a wide data width are collectively converted into a serial optical signal. In the case, or when a parallel electric signal having a wide data width is taken out from one serial optical signal, another device for multiplexing the electric signal outside the package is required. For this reason, since high-speed signals are input and output between these devices, they are electrically connected using a member that is matched in terms of high frequency, and the phase between the devices is set to a fine level in order to establish timing of data processing between the devices. Requires adjustment,
A great deal of adjustment time and specialized knowledge were required when using the device.

Further, when the optical signal input / output device and the electric signal multiplexing device are combined into a module, as described above, one module is multiply covered with the envelope and the shield plate. Inevitably, it has to be in a large-scale form, and there has been a problem that the production cost becomes enormous only by the number of modules that are configured.

The present invention has been made in consideration of the above circumstances, and an object thereof is to output a parallel electric signal from a serial optical signal or a serial optical signal from a parallel electric signal, and An object of the present invention is to provide an optical module that can be realized at a low cost with a simple configuration without requiring a shield plate, a radio wave absorber, or the like.

[0010]

The gist of the present invention realizes a serial-parallel or parallel-serial conversion function inside a package, and suppresses resonance at a fundamental frequency without providing a shield plate or a radio wave absorber. There is a structure that can.

That is, the present invention provides a package containing an optical semiconductor device and a speed converter for converting a serial electric signal into a parallel electric signal or a parallel electric signal into a serial electric signal, and an optical fiber cable provided in the package. In an optical module having a terminal for connecting a terminal, a terminal for inputting or outputting a parallel electric signal, and a terminal for inputting a clock signal, an elongated shape that is long in the direction in which the clock signal propagates through the package. And the length in the direction orthogonal to the longitudinal direction of the package is 1 / the wavelength corresponding to the fundamental frequency component of the clock signal.
It is characterized by being set shorter than 2. The following are preferred embodiments of the present invention. (1) An optical fiber connection terminal is provided on one end face in the longitudinal direction of the package. (2) A clock signal input terminal is provided on the other end surface of the package in the longitudinal direction. (3) On the longitudinal side surface (end surface in the lateral direction) of the package,
There must be an input / output terminal for electrical signals. (4) The package should have a rectangular parallelepiped shape. (5) Use a laser diode as an optical semiconductor device and a multiplexer (multiplexing circuit) as a speed converter. (6) Use a photodiode as an optical semiconductor element and a demultiplexer as a speed converter.

[0012]

According to the present invention, since the optical semiconductor element and the speed converter for performing serial-parallel or parallel-serial conversion are provided inside the package, the signals handled outside the package are parallel electric signals. This parallel electric signal has a low transmission speed, and impedance mismatch of the signal line or the terminal portion or resonance between the signal line and the envelope does not pose a problem. Moreover, since the shape of the package is defined as described above, it is possible to suppress resonance at the fundamental frequency of the clock signal without providing a shield plate or a radio wave absorber.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the drawings.

FIG. 1A is a perspective view showing a 10 Gbit / s optical transmission module according to an embodiment of the present invention, with a lid removed. Package 10
Is a rectangular parallelepiped shape, and a, b, and c respectively represent the size of the inner wall portion of the package 10. a is 13 mm,
b is 10 mm and c is 60 mm. By making a and b relatively small and making c long, the inside of the package can be considered as a waveguide having a and b in cross section.
The wavelength in the waveguide mode of 10 GHz, which is the frequency of the clock incorporated in the 10 Gbit / s device, is 30 mm, and the short sides a and b of the package 10 are shorter than 30 mm / 2. Resonance does not occur.

An optical signal input / output terminal of 10 Gbit / s and an optical fiber 11 are provided on one of the longitudinal end faces of the package 10, and a connector 12 for inputting a clock signal of 10 GHz is provided on the other end. On both side surfaces (surfaces having b and c as two sides) orthogonal to the longitudinal direction of the package 10,
A terminal 13 for inputting or outputting eight 1.25 Gbit / s signals is provided. Therefore, it has a device for performing serial-parallel conversion of eight parallel signals and one serial signal inside the package.

A pedestal 14 for mounting a substrate 15 is fixed in the package 10. The substrate 15 to be mounted on the pedestal 14 is fixed to the pedestal 14 by screw holes provided in at least two places on the pedestal 14. It The height of the uppermost portion of the substrate 15 provided inside the package is substantially the same as the height of the connection terminals 12 and 13 of the package 10. Board 1
5 includes a laser diode 1 as shown in FIG.
6, a laser driver 17 and a multiplexing circuit (speed converter) 18 for converting a parallel electric signal into a serial electric signal are mounted.

Signal line connection terminal 1 inside the package
Electrode terminals of ground potential are provided on both sides of 3.
Further, various optical components such as lenses may be arranged in the package 10 as needed. Further, the laser diode 16, the laser driver 17, and the multiplexing circuit 18
Need not be mounted on the same substrate 15 and may be mounted on another substrate.

With such a structure, the package 10
Since the laser diode 17 as well as the laser driver 17 and the multiplexing circuit 18 are housed in the package 10,
The signal to be input to the signal line terminal 13 provided at is a low-speed parallel electric signal, and does not cause problems such as impedance mismatch between the signal line and the terminal portion or resonance between the signal line and the envelope.
Moreover, since the length of the package 10 in the direction orthogonal to the longitudinal direction (the lengths of b and c) is shorter than 1/2 of the wavelength corresponding to the fundamental frequency component of the clock signal, the shield plate and the electromagnetic wave absorber. It is possible to suppress the resonance at the fundamental frequency without providing. Therefore, there is a great practical effect that the structure of the optical transmission module can be simplified and the manufacturing cost can be reduced.

Next, a more specific example of this embodiment will be described. As shown in FIG. 2, this module is composed of two independent substrates 20, 20 '. Board 2
A photoelectric conversion unit is mounted at 0 '. In order to improve the mounting efficiency, the optical fiber 28 is attached in a direction parallel to the main surface of the substrate 20 '. The laser diode 26 is mounted on a carrier, which is mounted perpendicular to the substrate 20 '. The carrier is provided with a through hole in a portion in contact with the light emitting surface of the laser diode 26, and the optical fiber 28 is inserted into the through hole.

The assembly process of the substrate 20 'is as follows. First, passive components such as resistors and capacitors are connected with a conductive epoxy adhesive. After confirming the DC continuity, the laser diode 26 is connected with the high melting point solder. After this, the substrate 20 'is screwed to the housing and the optical fiber 28 is attached. At this time, the substrate 2 is set so that the high frequency characteristics can be evaluated independently of the electric signal processing unit.
Ground electrodes are arranged on both sides of the input terminal at the end of the substrate from which the 0'input terminal is drawn. Therefore, it is possible to measure with a coplanar type high frequency probe, and it is possible to evaluate the characteristics of high-speed signals of 10 Gbps or more without being disturbed during measurement. In connection with the substrate 20 on which the electric signal processing unit is mounted, not only the signal line but also the opposing ground electrodes are electrically connected to each other, so that the signal can be transmitted while the mode discontinuity is minimized. It will be possible. Regarding electrical connection between the substrates, a ribbon having a width of 100 μm or more is used for bonding in order to suppress the inductive property.

An electric signal processing section is mounted on the board 20. In the embodiment, a laser driver 21 and a multiplexer 22 are mounted, the multiplexer 22 converts a low-speed parallel signal into a high-speed serial signal, and the laser driver 21 drives the laser diode 26. The clock signal (synchronization signal) φ is supplied to the substrate 20 from the side facing the substrate 20 '. Also in this case, the ground electrodes are arranged on both sides of the signal line in order to suppress the discontinuity of the mode of the connection portion and to enable the high frequency evaluation of the substrate 20 independently.

Laser driver 21 and multiplexer 22
Need to be electrically synchronized. In the embodiment, the external clock signal φ is used as the power divider 2 composed of a microwave circuit.
Divide 2 by 3. The distribution ratio can take a value other than 1: 1 depending on the input sensitivity of each integrated circuit, that is, the laser driver 21 and the multiplexer 22 in this embodiment. Since the multiplexer 22 has a differential input, one divided into two by the power distributor 23 is further converted into a differential signal by the differential signal generator 24 composed of a microwave circuit. In addition, the laser driver 21
And the multiplexer 22 are synchronized with each other by a phase adjuster 25 constituted by a microwave circuit. The main part of the phase adjuster 25 is composed of an island metallized pattern. In the case of the present embodiment, the phase adjuster 25 is inserted in the clock signal transmission line on the laser driver 21 side.

The phase adjustment is performed as follows. All active elements and passive elements are mounted on the substrate 20, all electrical connections other than the phase adjuster are performed, and independent electrodes in the microwave circuit for phase adjustment are connected by bonding wires so that there is no branching. , Completes the path of the clock signal φ supplied to the laser driver 21. In this state, the high speed operation characteristic is evaluated by detecting the error rate at a desired frequency.

Then, the measurement frequency is slightly increased or slightly decreased and the high speed operation characteristic is evaluated again. In the case of the present embodiment, assuming that the transmission path is longer on the laser driver 21 side than on the multiplexer 22 side, it is better to delay the phase with respect to the laser driver 21 if the high-speed operation characteristics improve when the frequency is slightly increased. Therefore, in the phase adjuster 25, the bonding wire is re-stretched so that the transmission path becomes longer. In the microwave circuit for phase adjustment, the minimum width of the electrical length that can be changed by the bonding wire is 10 ps or less. The size of the electric length to be lengthened is
It can be found by calculation based on the path difference of the clock signal φ between the multiplexer 22 and the laser driver 21 and the frequency at which the measured frequency and the characteristic when the frequency is shifted are the best.

After the signal transmission path in the phase adjuster 25 is determined, the path is fixed by using ribbon bonding instead of the bonding wire in order to minimize the characteristic deterioration of the connection portion. After the path is fixed, it is screwed to the housing, and the input terminal of the laser diode 26 on the substrate 20 'and the output terminal of the laser driver 21 on the substrate 20 are connected by ribbon bonding. At that time, the grounding electrodes are also connected to the signal lines such that the signal lines are sandwiched between the respective substrate ends with a gap of 500 μm or less.

In this embodiment, the clock signal φ is supplied from the outside, and for example, it is connected to the clock signal line of the substrate 20 through the field through of the K connector in the housing wall. The input signal to the multiplexer 22 is extracted to the board edge portion in the lateral direction of the rectangular board 20, and is connected to the outside through the field through formed in the housing wall.

FIG. 3 shows an embodiment in which the power distributor 23, the differential signal generator 24, and the phase adjuster 25 in FIG. 2 are composed of microstrip lines and thin film resistors. 23a corresponds to the power distributor 23, 24a corresponds to the differential signal generator 24, and 25a corresponds to the phase adjuster 25. 23a is called a Wilkinson type power distributor in the field of microwave engineering. The signal input from the wiring 31 passes through the power distributor 23a and is distributed to the wirings 32 and 35 at a constant power ratio. This ratio can be set to a desired value by changing the resistance value and the wiring width in the power distributor 23a. The wiring 32 is connected to the differential signal generator 24a. The differential signal generator 24a is called a rat race hybrid in the field of microwave engineering. The signal input from the wiring 32 passes through the differential signal generator 24a and is distributed into two signals whose phases are almost opposite to each other.
4 respectively. The wiring 35 is the phase adjuster 25a.
Connected to. In the phase adjuster 25a, the metallized electrodes are connected to each other so as to take a wiring path having an optimum electrical length, and the phase is adjusted.

Thus, in this embodiment, the signal distributor 23
a, the differential signal generator 24a and the phase adjuster 25a are configured by the microstrip line, so that the distribution of the synchronization signal, the phase adjustment, and the differential output can be performed without using the integrated circuit that controls the maximum operating frequency of the module. Etc. are possible. Also,
Unlike the one in which the synchronization signal is simply branched by wiring, it can sufficiently cope with the increase in the frequency of the synchronization signal, and because the integrated circuit is not used for the synchronization signal processing, the total power consumption of the module can be suppressed. it can. In particular, since the synchronous signal processing unit has to operate the integrated circuit at high speed and tends to consume a large amount of current, the synchronous signal processing unit of the optical communication module is configured by a microwave circuit in view of the heat dissipation structure. That will have a great effect.

The present invention is not limited to the above embodiment. In the embodiment, the example applied to the optical transmission has been described, but it goes without saying that the present invention can also be applied to the optical reception. Further, the shape of the package is not necessarily limited to the rectangular parallelepiped, and may be a long shape that is long in the propagation direction of the clock signal. Furthermore, the size of the package is not limited to the embodiment, and the length in the direction orthogonal to the longitudinal direction may be shorter than 1/2 of the wavelength corresponding to the fundamental frequency component of the clock signal.

The plane circuit as the clock signal processing circuit is not limited to the microstrip line, and may be formed by a coplanar line, a strip (triplate) line, or a grounded coplanar line. In addition, various modifications can be made without departing from the scope of the present invention.

[0031]

As described above, according to the present invention, the speed converter for performing serial-parallel or parallel-serial conversion is provided inside the package together with the optical semiconductor element, so that the package and the external device are connected. Can be connected with a low speed signal. Moreover, since the length of the package in the direction orthogonal to the longitudinal direction is set to be shorter than 1/2 of the wavelength corresponding to the fundamental frequency component of the clock signal, it is not necessary to provide a shield plate or an electromagnetic wave absorber inside the package. Cavity resonance can be suppressed. Therefore, it is possible to realize an optical module that outputs a parallel electrical signal from a serial optical signal or a serial optical signal from a parallel electrical signal, and does not require a shield plate, a radio wave absorber, or the like, and has a simple configuration. It can be realized at low cost.

[Brief description of drawings]

FIG. 1 is a perspective view showing a schematic configuration of an optical transmission module according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a more specific circuit used in the embodiment.

FIG. 3 is a diagram showing an example in which a power supply distributor, a differential signal generator, and a phase adjuster used in the embodiments are formed by a planar circuit.

FIG. 4 is a plan view showing the basic configuration of a conventional optical transmission module.

[Explanation of symbols]

 10 ... Package 11 ... Optical fiber cable 12 ... Electrical terminal for clock input 13 ... Connection terminal for signal input / output or power supply 14 ... Pedestal 15 ... Substrate 16 ... Laser diode 17 ... Laser driver 18 ... Multiplexing circuit 20, 20 '... Substrate 21 ... Laser driver 22 ... Multiplexer 23, 23a ... Power distributor 24, 24a ... Differential signal generator 25, 25a ... Phase adjuster 26 ... Laser diode 28 ... Optical fiber 31-35 ... Wiring

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location H04B 10/06 (72) Inventor Kunio Yoshihara 1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Stock ceremony Company Toshiba Research and Development Center (72) Inventor Teruko Takagi 1 Komukai Toshiba Town, Saiwai-ku, Kawasaki City, Kanagawa Stock Company Toshiba Research and Development Center (72) Inventor Atsushi Hanari Komukai Toshiba, Kawasaki City, Kanagawa Prefecture Town No. 1 Incorporated company Toshiba Research and Development Center (72) Inventor Yasushi Shizuki No. 1 Komukai Toshiba Town, Kouki-ku, Kawasaki City, Kanagawa Prefecture Incorporated company Toshiba Research and Development Center (72) Inventor Ayako Kawasaki, Kanagawa Prefecture Komukai Toshiba-cho, Sachi-ku, Yokohama-shi Incorporated company Toshiba Research and Development Center

Claims (1)

[Claims] 1. A package containing an optical semiconductor element and a speed converter for converting a serial electric signal into a parallel electric signal or converting a parallel electric signal into a serial electric signal, and an optical fiber cable provided in this package are connected. A terminal for inputting or outputting a parallel electric signal, and a terminal for inputting a clock signal or a clock generation circuit, wherein the package has an elongated shape long in the direction in which the clock signal propagates. An optical module, characterized in that the length of the package in the direction orthogonal to the longitudinal direction is shorter than 1/2 of the wavelength corresponding to the fundamental frequency component of the clock signal.