JPH08129196A - Optical switch module - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an optical switch module that enables highly accurate optical interconnection. [Constitution] The switch module has one input port 3 for inputting an optical signal and a plurality of output ports 6 for outputting an electric signal. On the module base 1, a spatial light deflecting element 2 for spatially deflecting the optical signal supplied from the input port 3 and an output light S from this deflecting element 2 are received and output to the output port 6 as an electric signal. The PD array 5 for taking out is mounted. The optical deflection element 2 includes a waveguide layer formed on a semiconductor substrate, a diffraction grating that is formed on the waveguide layer and extracts the second-order diffracted light of the light transmitted through the waveguide layer to the outside, and a clad layer formed on the diffraction grating. It has electrodes for variably controlling the refractive index of the cladding layer and the waveguide layer provided on the back surface of the substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical switch module used for optical transmission switching in an information processing system or a communication system using optical signals.

[0002]

2. Description of the Related Art In recent years, in the field of information processing, for example, development of so-called optical interconnection technology that uses optical signals for information transmission between boards and processors in a large computer has been advanced. In this optical interconnection, an optical switching element for spatially switching optical signals and an element for controlling parallel optical information transmission are desired. An optical waveguide element having a diffraction grating formed therein is promising as such a space-type optical deflecting element, but conventionally known ones can only emit light to the external space, and spatial light switching, etc. Can't handle.

[0003]

However, even if the spatial deflection element capable of controlling the deflection angle of the emitted light can be realized, it is intended to use it as an optical switching element having a spatial address function between boards. Then, a big problem occurs in implementation. For example, consider a case where a spatial light deflecting element is arranged on a main board, and the emitted light is deflected and transmitted to a light receiving element array or the like on a facing sub board at a distance of several cm. At this time, even if the spot diameter of the light beam is set to about 1 mm, extremely high-precision alignment is required between the mounting position of the light deflection element on the main board and the mounting position of the light receiving element array on the sub board. Considering the alignment accuracy when these boards are fitted into the stack, such a spatial optical interconnection is not very practical.

The present invention has been made in view of such circumstances, and an object thereof is to provide an optical switch module which enables highly accurate optical interconnection.

[0005]

SUMMARY OF THE INVENTION The present invention is an optical switch module including an optical deflecting element for spatially deflecting an incident optical signal, the optical deflecting element comprising a semiconductor substrate and a substrate. A waveguide layer formed in, a diffraction grating for extracting the second-order diffracted light of the light formed on the waveguide layer and transmitted through the waveguide layer to the outside, and a clad layer formed on the diffraction grating, The optical deflection element has the clad layer and an electrode for variably controlling the refractive index of the waveguide layer provided on the back surface of the substrate, and the optical deflection element is on the module base, and the deflection of the emitted light is parallel to the module base. The light receiving element array is mounted on the module base so as to detect the emitted light of the light deflecting element according to the deflection angle thereof.

[0006]

According to the present invention, the space-type light is an optical deflecting element for emitting the second-order diffracted light to the outside, and the deflection angle can be varied by controlling the refractive index of the waveguide layer by an external bias. A deflection element is used. The spatial light deflector is mounted on the module base so that the emitted light is deflected in a plane parallel to the module base, and the module base detects the light emitted from the spatial light deflector. A light receiving element array is mounted. That is, it is modularized so that optical switching and photoelectric conversion are internally performed with an input port for inputting one optical signal and a plurality of output ports for outputting electric signals.

According to the present invention, since the alignment within the switch module is performed on the module base,
It can be easily and highly accurate compared with the one between boards described above. And if the optical switch module of the present invention is mounted on a board, spatial optical switching and photoelectric conversion are performed within the board, so that, for example, by connecting with an opposing board by an electric signal line or the like, the board It does not require difficult alignment as compared with the method of performing spatial optical switching between them.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of an optical switch module according to an embodiment of the present invention. This switch module has one input port 3 for inputting an optical signal and a plurality of output ports 6 for outputting electric signals. Module base 1
Above, a spatial optical deflector 2 for spatially deflecting the optical signal supplied from the input port 3 and an output light S from the deflector 2 are received and taken out to the output port 6 as an electric signal. A photodiode (PD) array 5 is mounted.

Although an optical fiber is shown as the input port 3 in the figure, this may be a connector capable of coupling the optical fiber. The spatial light deflector 2 is capable of variably controlling the deflection angle by applying an external bias. The details will be described later, but as shown in the figure, the output light S has a predetermined angle within a plane parallel to the module base 1. It is arranged so that it can be deflected in the range of θ. The module is provided with voltage application terminals 4a and 4b so that an external power supply 7 can be connected thereto.

FIG. 2 is a perspective view showing the spatial light deflector 2 by cutting it out. The optical deflection element 2 has a waveguide layer 21 formed on the substrate 20 and a diffraction grating 23 formed at the interface between the two clad layers 22a and 22b laminated on the waveguide layer 21. . The waveguide layer 21 has, for example, a multiple quantum well (MQW) structure. The diffraction grating 23 is configured to extract the second-order diffracted light of 1.3 μm light transmitted through the waveguide layer 21 in the direction perpendicular to the substrate surface.
The refractive index and the grating pitch of the waveguide layer 21 and the medium in the vicinity thereof are set.

When p-type InP is used as the substrate 20,
The waveguide layer 21 is made of i-type InP and InGaAsP 10
It is composed of MQW layers alternately stacked by about nm. The absorption wavelength is set to, for example, 1.15 μm. The first cladding layer 22a on this is an n-type InGaAsP layer whose absorption wavelength is set to a shorter wavelength side than the waveguide layer 21, and the second cladding layer 22b is an n-type InP layer.
The conductivity type of each part may be reversed.

By setting the composition as described above, the light deflection element 2
Then, from the waveguide layer 21 to the first cladding layer 22a and the second cladding layer 22a.
The refractive index distribution is formed so that the refractive index becomes smaller in the order of the clad layer 22b. The diffraction grating 23 embedded in the optical deflection element 2 is formed on the surface of the thin first clad layer 22a and is arranged at a position extremely close to the waveguide layer 21. The portion of the light exuding is coupled to the diffraction grating 23.

An electrode 24 having a light extraction window 25 is formed on the surface of the clad layer 22, and an electrode 26 facing the same is formed on the back surface of the substrate 20. By applying a voltage between the electrodes 24 and 26 that is positive or negative on the electrode 24 side, the refractive index in the vicinity of the diffraction grating 23 of the light deflection element 2 is controlled by the so-called electro-optical effect due to the internal electric field. Thereby, the diffraction angle of the second-order diffracted light from the diffraction grating 23 due to the coupling from the waveguide layer 21, that is, the window 2
The deflection angle of the light extracted via 5 is controlled.

As described above, the optical switch module according to this embodiment has one input port for inputting an optical signal and a plurality of output ports for switching the input light to take out as an electric signal. It is integrated with the PD array to perform spatial optical switching within the module. The optical axis alignment within the module is easy. The board on which this module is mounted and another board can be coupled by an electric signal line. Therefore, unlike the method in which optical coupling between boards is spatially performed, highly accurate alignment between boards is not required.

Further, there is no problem of a change in the external environment after mounting, such as a time-dependent optical axis shift due to the influence of temperature fluctuation or vibration, a decrease in coupling efficiency, and an increase in signal error rate, and a highly reliable optical interconnection. Will be possible.

[0016]

As described above, according to the present invention, the spatial light deflection element capable of changing the deflection angle by the external bias and the light receiving element array for converting the emitted light into an electric signal deflect the emitted light. Is mounted on the module base so as to be performed in a plane parallel to the module base, and has one input port for receiving an optical signal and a plurality of output ports for outputting an electric signal to form a switch module. Optical axis alignment in the switch module can be easily performed with high accuracy.
When the optical switch module of the present invention is mounted on a board, spatial optical switching is performed within the board, and the opposing board is connected by an electric signal line, so that difficult alignment is not required.

[Brief description of drawings]

FIG. 1 shows the configuration of an optical switch module according to an embodiment of the present invention.

FIG. 2 shows a configuration of an optical deflecting element used in the example.

[Explanation of symbols]

1 ... Module base, 2 ... Spatial light deflection element, 3 ... Input port, 4a, 4b ... Voltage application terminal, 5 ... PD array, 6 ... Output port, 7 ... External power supply.

Claims (1)

[Claims] 1. An optical switch module comprising an optical deflecting element for spatially deflecting an incident optical signal, wherein the optical deflecting element comprises a semiconductor substrate and a waveguide layer formed on the substrate. , A diffraction grating for extracting the second-order diffracted light of light transmitted through the waveguide layer formed on the waveguide layer, a clad layer formed on the diffraction grating, and the clad layer and the back surface of the substrate. An electrode for variably controlling the refractive index of the provided waveguide layer, wherein the light deflection element is provided on a module base such that the emitted light is deflected in a plane parallel to the module base. An optical switch module, which is mounted and on which a light-receiving element array for detecting light emitted from the light-deflecting element according to a deflection angle thereof is mounted on the module base.