Optical semiconductor device and method for manufacturing the same

Abstract

An optical semiconductor device comprising a plurality of semiconductor lasers formed on a single substrate is provided, in which each of said semiconductor lasers emits a laser lights having designed different oscillating wavelength. This optical semiconductor device is provided by maintaining the coupling coefficient of each of said semiconductor lasers at a constant value by adjusting the composition of an optical guide layer or the mask width for the MOVPE growth.

What is claimed is:  
     
         1 . An optical semiconductor device comprising a plurality of semiconductor lasers formed on a single substrate, wherein each of said semiconductor lasers emits laser lights having oscillating wavelengths differing from each other by different cycles of a plurality of diffraction gratings, wherein a composition of an optical guide layer in contact with one of said diffraction gratings is determined such that the coupling coefficient of each of said semiconductor lasers is maintained at the same value.  
     
     
         2 . An optical semiconductor device comprising a plurality of semiconductor lasers formed on a single substrate, wherein each of said plurality of semiconductor lasers emits longitudinal single mode laser lights having different oscillating wavelengths due to a distributed feedback operation of a periodic change of the refractive index in said plurality of semiconductor lasers and wherein said plurality of semiconductor lasers have the same coupling coefficient by being provided with a diffraction grating embedded semiconductor layer each having a refractive index corresponding to the oscillating wavelength.  
     
     
         3 . An optical semiconductor device according to    claim 1   , wherein said semiconductor laser is a distributed feedback semiconductor laser.  
     
     
         4 . An optical semiconductor device according to    claim 1   , wherein each of said plurality of diffraction gratings has the same height.  
     
     
         5 . An optical semiconductor device according to    claim 1   , wherein each of said plurality of semiconductor lasers comprises a diffraction grating embedded semiconductor layer made of InGaAsP having a band-gap wavelength (energy) corresponding to the oscillating wavelength thereof.  
     
     
         6 . An optical semiconductor device according to    claim 1   , wherein said substrate is made of InP, said diffraction gratings are formed to the same height from said substrate, and said optical guide layer is made of InGaAsP formed on said diffraction gratings.  
     
     
         7 . An optical semiconductor device according to    claim 1   , wherein an optical modulator is monolithically integrated with said semiconductor laser.  
     
     
         8 . An optical semiconductor device comprising a plurality of semiconductor lasers provided with a plurality of diffraction gratings having cycles different from each other, an InGaAsP guide layer formed on or below said diffraction gratings, a multi-quantum well layer, and an InP clad layer on an InP substrate, and which emit laser lights having different wavelengths determined by the cycle of said diffraction gratings, wherein the refractive index of said guide layer is adjusted so as to equalize the coupling coefficients of the respective semiconductor lasers.  
     
     
         9 . A manufacturing method for collectively manufacturing, on a single substrate, an optical semiconductor device comprising a plurality of semiconductor lasers which emit longitudinal single mode laser lights having different wavelengths due to a distribution feedback operation of a periodic change of the refractive indexes in the respective semiconductor lasers, wherein the refractive indexes of diffraction grating embedded semiconductor layers are decreased (or increased) so as to cancel the difference of the coupling coefficients of respective semiconductor lasers whose coupling coefficients are increased (or decreased) when the diffraction gratings for generating a distribution feedback operation are formed in the same configuration and the refractive indexes of said diffraction grating embedded semiconductor layers are fixed at the same value.  
     
     
         10 . A manufacturing method for collectively manufacturing, on a single substrate, an optical semiconductor integrated device comprising a plurality of semiconductor lasers which emit longitudinal single mode laser lights having different wavelengths due to a distributed feedback operation of a periodic change of the refractive indexes in the respective semiconductor lasers, and a plurality of optical semiconductor portions integrally formed with said semiconductor lasers for receiving the respective laser lights from said plurality of semiconductor lasers, wherein the refractive indexes of said diffraction grating embedded semiconductor layers are decreased (or increased) so as to cancel the difference of the coupling coefficients of respective semiconductor lasers for the semiconductor lasers whose coupling coefficient is increased (or decreased) when the diffraction gratings for generating a distributed feedback operation are formed in the same configuration and the refractive indexes of the diffraction grating embedded semiconductor layers are fixed at the same value.  
     
     
         11 . A manufacturing method according to    claim 10   , wherein said optical semiconductor integrated device comprises longitudinal single mode oscillating semiconductor lasers and optical modulators.  
     
     
         12 . A manufacturing method according to    claim 9   , wherein the band-gap wavelengths of said diffraction grating embedded semiconductor layers are made shorter (or longer) so as to cancel the difference of the coupling coefficients of the respective semiconductor lasers for the semiconductor lasers whose coupling coefficients are increased (or decreased) when the diffraction gratings for generating a distributed feedback operation are formed in the same configuration and the band-gap wavelengths of said diffraction grating embedded semiconductor layers are fixed at the same value.  
     
     
         13 . A manufacturing method according to    claim 12   , wherein said diffraction grating embedded semiconductor layer is made of InGaAsP, and the change of the refractive index of said InGaAsP layer is executed by changing the compositional ratio of In and Ga in Group III in the periodic table.  
     
     
         14 . A manufacturing method according to    claim 12   , wherein said diffraction grating embedded semiconductor layer is made of InGaAsP, and the change of the band-gap wavelength is executed by changing the compositional ratio of As and P belonging to Group V of the periodic table.  
     
     
         15 . A manufacturing method according to    claim 9   , wherein the method for changing the refractive index or the band-gap wavelength of said diffraction grating embedded semiconductor layer is a selective metal organic vapor phase growth method.  
     
     
         16 . A manufacturing method according to    claim 9   , wherein the method for changing the refractive index or the band-gap wavelength of said diffraction grating embedded semiconductor layer is provided by adjusting a flowing ratio of Group V materials in an atmospheric pressure double fluid layer type metal organic vapor phase growth method.  
     
     
         17 . An optical semiconductor device according to    claim 1    or the semiconductor device obtained by the manufacturing method according to    claim 16    which is applied to an optical communication module, wherein the optical communication module comprises: a waveguide device for guiding an output light from said optical semiconductor device to the outside, a mechanism for inputting the output light from said semiconductor device to the waveguide device, and an electrical interface for driving said semiconductor device.  
     
     
         18 . An optical semiconductor device according to    claim 17   , wherein said semiconductor device according to    claim 1    or the semiconductor device obtained by the manufacturing method according to    claim 16    is applied to an optical communication apparatus, which comprises an optical transmission device provided with said optical communication module and a receiving device for receiving the output light from said light transmission device.