The present invention relates to an optical communication module between devices, between boards or on backplane of information equipment such as a router, a server or a storage, and to an optical signal transmission method.
Recently, as the amount of information handled by information equipment such as a router, a server or a storage dramatically increases, the limit of electric transmission in interconnection between devices, between boards or on backplane of the information equipment has become evident, and thus needs for interconnection using optical transmission, in particular, parallel optical interconnection using a plurality of optical transmission paths or wavelength multiplexing interconnection using a plurality of wavelengths have been increased. To cope with the needs, there have been developed array light interfaces for the interconnection.
As a conventional example of the wavelength multiplexing interconnection module using the plurality of wavelengths, there is known the arrangement shown in FIG. 2 of Non-Patent Document 1, and
Note that as technologies relating to the present invention, Patent Document 1 discloses a face-emitting laser disposed in an array state, a photo detector, and an optical transmission path connected thereto, and Patent Document 2 discloses two-dimensional array-shaped optical connector.
Non-Patent Document 1: 2001 Electric Component and Technology Conference “Low Cost CWDM Optical Transceivers” Eric B. Grann
Patent Document 1: Japanese Patent Application Laid-Open Publication No. 2001-42171
Patent Document 2:Japanese Patent Application Laid-Open Publication No. 09-133842
However, in the wavelength multiplexing interface module shown in Non-Patent Document 1, it is contemplated that use of the multiwavelength monolithic integrated VCSEL that is collectively grown on the same substrate as a light source causes a significant technical disadvantage as to a resonant wavelength control, a gain peak wavelength and a light emission diameter control, and it is difficult to reduce a cost by using it. When, for example, the multiwavelength monolithic integrated VCSEL that is collectively grown on the same substrate is used, an disadvantage in production arises. That is, when a gallium arsenide (GaAs) substrate is used as the substrate, although it is required to control the thickness and the composition of the respective films of an aluminum gallium arsenide multilayer film on the substrate for the resonant wavelength control and the gain peak wavelength control (for example, it is necessary to form a multilayer film whose aluminum composition is controlled for the resonant wavelength control), it is not easy to control the aluminum composition. Further, the wavelength multiplexing interface module is also defective in operation in that it has no substitutability. That is, if one element is broken in a VCSEL device, the substrate must be entirely replaced.
An object of the present invention is to provide an array light interface module for a wavelength multiplexing interconnection using a plurality of wavelengths that can solve the above disadvantages as well as can enhance the degree of freedom of disposition of optical devices, can have substitutability, can reduce electric crosstalk between optical devices and can prevent deterioration of the optical devices due to heat.
According to a first aspect of the present invention, there is provided an optical communication module including a plurality of one-dimensional array-shaped photoelectric conversion modules, a plurality of light transmission members optically connected to the plurality of one-dimensional array-shaped photoelectric conversion modules, and a two-dimensional array-shaped optical connector whose one connector end is optically connected to the plurality of light transmission members, wherein the plurality of one-dimensional array-shaped photoelectric conversion modules correspond to optical signals having respective different wavelengths, and the other connector end of the two-dimensional array-shaped optical connector is optically connected to a wavelength multiplexer/de multiplexer.
According to a second aspect of the present invention, there is provided an optical signal transmission method including the steps of demultiplexing an optical signal having a different wavelength by a wavelength multiplexer/demultiplexer optically connected to one connector end of a two-dimensional array-shaped optical connector, and outputting the demultiplexed outputs from the other end of the two-dimensional array-shaped optical connector to a plurality of one-dimensional array-shaped photoelectric conversion modules.
According to a second aspect of the present invention, there is provided an optical signal transmission method including the steps of inputting optical signals having a different wavelength from a plurality of one-dimensional array-shaped photoelectric conversion modules to one end of a two-dimensional array-shaped optical connector, and modulating the optical signals by a wavelength multiplexer/demultiplexer optically connected to the other end of the two-dimensional array-shaped optical connector and outputting the modulated optical signal.
Note that the one-dimensional array-shaped photoelectric conversion module includes each light receiving element for converting an optical signal into an electronic signal, each light emitting element for converting an electronic signal into an optical signal, or each device composed of a mixture of a light receiving element and a light emitting element, these devices being arranged in a one-dimensional array state. That is, the photoelectric conversion module may be composed of only the light receiving elements, only the light emitting elements, or only the devices that each is composed of the mixture of the light receiving element and the light emitting element. However, it may include the other devices such as an IC driver.
In the present invention, the photoelectric conversion module has a one-dimensional array shape that has a high degree of freedom of layout and is excellent in substitutability. Optical signals having a different wavelength are output from the plurality of photoelectric conversion modules to the two-dimensional array-shaped optical connector and further multiplexing functions are put together by optically connecting the wavelength multiplexer/demultiplexer to the two-dimensional array-shaped optical connector, thereby a multiplexed optical signal is output.
Further, demultiplexing functions are put together by optically connecting the wavelength multiplexer/demultiplexer to the two-dimensional array-shaped optical connector. Multiplexed light is separated for each wavelength and output to the plurality of one-dimensional array-shaped photoelectric conversion module that has a high degree of freedom of layout and is excellent in substitutability.
According to the present invention, since the mounting shape in a photoelectric conversion module is a one-dimensional shape, the layout of the photoelectric conversion modules can be optionally determined on a board (substrate), and the photoelectric conversion modules can be replaced in a unit of one-dimensional array. Since each of the one-dimensional array-shaped photoelectric conversion modules can be disposed with flexibility, the one-dimensional array-shaped photoelectric conversion modules can be designed with a high degree of freedom in consideration of electric crosstalk and heat dissipation. When it is intended to transmit optical signals in parallel, the light emitting element and/or the light receiving element, which can be made accurately at a low cost, can be mounted without using a monolithic integrated multiwavelength light emitting element and/or a monolithic integrated multiwavelength light receiving element, whose realization of them is difficult.
Further, it is possible to put the wavelength multiplexing/demultiplexing functions together by optically connecting the wavelength multiplexer/demultiplexer to the two-dimensional array-shaped connector.
An embodiment of the present invention will be described below in detail with reference to the accompanying figures.
A one-dimensional VCSEL array 309-1 having a single wavelength and an IC driver 304 electrically connected to the VCSEL array 309-1 are mounted in the one-dimensional array-shaped photoelectric conversion module 308-1. It is preferable that the VCSEL array 309-1 is a monolithic integrated array from a point of view of mounting cost and mounting accuracy. Further, a VCSEL array 309-2 (not shown) is mounted on the photoelectric conversion module 308-2, and a VCSEL array 309-3 (not shown) is mounted on the photoelectric conversion module 308-3, and they are composed similarly to the one-dimensional array-shaped photoelectric conversion module 308-1. The one-dimensional array-shaped photoelectric conversion module 308-1 is optically connected to a fiber sheet 306 having mechanical flexibility through an optical connector 305 that can bend an optical path at an approximately right angle (including a right angle and the range of angle near to a right angle in view of dispersion and the like in production). Note that although the optical connector 305 that can bend the optical path at an approximately right angle is used here because light is emitted from the VCSEL array 309-1 onto the surface of a substrate (board) 301 in a vertical direction. However, when light is emitted therefrom in parallel with the substrate surface, or the fiber sheet 306 is disposed in the vertical direction with respect to the substrate surface, the optical connector 305 need not be used. The fiber sheet 306 includes a plurality of optical fibers 306A sandwiched between sheets and bonded thereto by an adhesive and has the plurality of optical fibers 306A in a part thereof as shown in
As the fiber sheets 306, which extend from the one-dimensional array-shaped photoelectric conversion modules 308-1 to 308-3, approach to an end of the board 301, they are laminated (piled up) with each other and connected to a two-dimensional array-shaped optical connector 307 at the board end as shown in
The parallel electric signals formed by the driver IC 304 are input to the respective VCSEL arrays 309-1 and are subjected to photoelectric conversion. The driver IC 304 disposed to each of the photoelectric conversion modules is controlled by a not shown controller disposed on the board 301, and causes all of or a part of the VCSEL arrays to emit light, in all of or a part of the photoelectric conversion modules on the board 301 (step S11 of
With this arrangement, since the mounting shape in photoelectric conversion module 308 is the one dimensional array shape, it has a high degree of freedom of layout and further can be replaced in a unit of one dimensional array. Further, since the one-dimensional array-shaped photoelectric conversion modules 308-1 to 308-3 can be flexibly disposed, wirings and heat dissipation can be designed with a high degree of freedom in consideration of electric crosstalk. Further, since the one-dimensional array-shaped photoelectric conversion module is connected to the connector 305 using the above arrangement, a dead space required when an ordinary MT connector (Mechanically Transferable Connector) is inserted and extracted can be omitted, thereby space-saving mounting can be realized. Further, in the wavelength multiplexer/demultiplexer 311 having a two-dimensional array shape at the board end, the wavelengths which are different from each other in a unit of module are multiplexed and connected to a one-dimensional optical fiber 314 through an optical connector.
With this arrangement, it is possible to simply transmit signals whose wavelengths are multiplexed, in parallel with each other. The plurality of one-dimensional array-shaped photoelectric conversion modules correspond to the optical signals having a different wavelength. When, for example, the wavelength of the optical signal from the photoelectric conversion module 308-1 is represented by λ1, the wavelength of the optical signal from the photoelectric conversion module 308-2 is represented by λ2, and the wavelength of the optical signal from the photoelectric conversion module 308-3 is represented by λ3 (the wavelengths λ1, λ2, and λ3 a different from each other, these wavelengths λ1 to λ3 are output after they are multiplexed. Note that the photoelectric conversion modules need not necessarily have a single wavelength. That is, to permit the photoelectric conversion modules to transmit a plurality of wavelengths when necessary, the respective photoelectric conversion modules can be designed and transmit optical signals. For example, it is possible that the optical signal from photoelectric conversion module 308-1 has the wavelengths λ1 and λ2, the optical signal from the photoelectric conversion module 308-2 has the wavelengths λ3 and λ4, and the optical signal from the photoelectric conversion module 308-3 has the wavelengths λ5 and λ6 (the wavelengths λ1 to λ6 are different from each other, respectively). In this case, the multilayer film filters 313 are appropriately designed to the plurality of wavelength signals from the photoelectric conversion module. As described above, even if the plurality of wavelengths are transmitted from the photoelectric conversion module, since the optical signals having the different wavelength are transmitted as they are divided into the plurality of photoelectric conversion modules, the photoelectric conversion modules can be replaced individually. Consequently, the photoelectric conversion modules can be more easily manufactured than a conventional case in which the multiwavelength monolithic integrated VCSEL that carries out a collective growth on the same substrate is used.
The VCSEL array 309 of each photoelectric conversion module may be displaced with a PD (Photo Detector) array. In this case, the signal flows in a direction opposite to that of the VCSEL array, and the PD array acts as an array light interface receiving module.
The VCSEL array 309 may be mounted in the photoelectric conversion module 308 in mixture with the PD array. In this case, the photoelectric conversion module 308 acts as an array light transmitting/receiving module. That is, when the VCSEL array 303 and the PD array are mounted in one photoelectric conversion module, the number of channels per one photoelectric conversion module is set to ten channels as shown in
The photoelectric conversion modules 308-1 to 308-3 may be separately disposed on a plurality of boards. In this case, the fiber sheets 306 from the photoelectric conversion modules 308-1 to 308-3 on the plurality of boards are gathered to the one two-dimensional array-shaped optical connector 307 and connected thereto. That is, the embodiment invention is not limited to the case in which the plurality of photoelectric conversion modules 302 are mounted on the one board as shown in
Further, as a method of disposing the photoelectric conversion module 308, although the photoelectric conversion modules 308 are disposed in parallel with the board end of in
An optical modulator may be built in the one-dimensional array-shaped photoelectric conversion module 308. In this case, the photoelectric conversion module acts as a photoelectric conversion module that can deal with a higher bit rate as compared with a case in which no optical modulator is built in.
The fiber sheet 306 may be displaced with a tape fiber. The tape fiber is formed by disposing a plurality of optical fibers and bonding them with an adhesive. The fiber sheet 306 may be displaced with a flat optical waveguide.
The wavelength multiplexer/demultiplexer 311 may be composed of a diffraction grating. Otherwise, the wavelength multiplexer/demultiplexer 311 may be composed of a fiber type coupler, a fiber type WDM filter, and the like. Further, the wavelength multiplexer/demultiplexer 311 may be composed of an array waveguide grating.
Number | Date | Country | Kind |
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2005-014119 | Jan 2005 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP2006/300841 | 1/21/2006 | WO | 00 | 7/20/2007 |