Method of manufacturing a semiconductor optical waveguide array and an array-structured semiconductor optical device

Abstract

In a method of manufacturing a semiconductor optical waveguide array in an ultra-high integration, the device yield per wafer is considerably increased and uniform and improved characteristics are obtained. In this method, there is manufactured a semiconductor optical waveguide array including a plurality of optical waveguides in an array structure in stripe-shaped growth regions enclosed by dielectric thin films on a substrate. The waveguides are fabricated through a selective crystal growth process and include a semiconductor multilayer structure including a quantum well layer or a semiconductor multilayer structure including a bulk layer. Namely, there is formed a plurality of stripe-shaped growth regions elongated parallel to each other, the regions being enclosed with a dielectric thin film. In each growth region, a semiconductor multilayer structure is selectively grown by metallo-organic vapor phase epitaxy (MOVPE). In the selective growth, the growth regions are parallel to each other with an interval therebetween, the interval being less than a diffusion length of a source material in a reactive tube during the crystal growth. Assuming that the dielectric thin film arranged between the respective growth regions has a width Wa and a first outer-most dielectric thin film and a second outer-most dielectric thin film arranged respectively outside of outer-most ones of the growth regions respectively have widths W m1 and W m2 , there is satisfied a relationship of W m1 >Wa and W m2 >Wa.

What is claimed is:  
     
         1 . A method of manufacturing a semiconductor optical waveguide array including a plurality of optical waveguides in an array structure in stripe-shaped growth regions enclosed by dielectric thin films on a substrate, the optical waveguide being fabricated through a selective crystal growth and having a semiconductor multilayer structure including a quantum well layer or a semiconductor multilayer structure including a bulk layer, comprising the following steps of: 
 on an occasion of fabricating a plurality of stripe-shaped growth regions elongated parallel to each other, the regions being enclosed with dielectric thin films and selectively growing in each of the growth regions by metallo-organic vapor phase epitaxy a semiconductor multilayer structure including a quantum well layer or a semiconductor multilayer structure including a bulk layer;    the growth regions being parallel to each other with an interval therebetween in the selective growing step the interval being less than a diffusion length of a source material in a reactive tube during the crystal growth,    the dielectric thin films arranged between the respective growth regions each having a width Wa,    a first outer-most dielectric thin film and a second outer-most dielectric thin film arranged respectively outside of outer-most ones of the growth regions respectively having widths W m1  and W m2 ,    the widths Wa, W m1  and W m2  satisfying a relationship of W m1 >Wa and W m2 >Wa.    
     
     
         2 . The method of manufacturing a semiconductor optical waveguide array in accordance with    claim 1   , further including the step of; 
 setting the widths W m1  and W m2  respectively of the first and second outer-most dielectric thin films to values satisfying a condition of W m1 ≠W m2  and thereby changing composition or a thickness of each of the semiconductor optical waveguides of the array.    
     
     
         3 . The method of manufacturing a semiconductor optical waveguide array in accordance with    claim 1   , further including the step of; 
 completely covering by a dielectric thin film each of the regions enclosed by the plural growth regions.    
     
     
         4 . The method of manufacturing a semiconductor optical waveguide array in accordance with    claim 1   , further including the step of; 
 setting an interval between the plural growth regions to 50 μm or less.    
     
     
         5 . The method of manufacturing a semiconductor optical waveguide array in accordance with    claim 1   , further including the step of; 
 setting a length of each of the plural growth regions to 10 μm or less.    
     
     
         6 . The method of manufacturing a semiconductor optical waveguide array in accordance with    claim 1   , further including the step of; 
 changing either one of a number of the growth regions and the widths Wa, W m1 , and W m2  of the dielectric thin films in a longitudinal direction of the growth regions and thereby changing composition or a thickness of each of the semiconductor optical waveguides of the array in the longitudinal direction.    
     
     
         7 . The method of manufacturing a semiconductor optical waveguide array in accordance with    claim 1   , further including the step of; 
 changing each interval between the plural growth regions in a longitudinal direction of the growth regions and thereby changing an interval between the semiconductor optical waveguides.    
     
     
         8 . The method of manufacturing a semiconductor optical waveguide array In accordance with    claim 1   , further including the step of; 
 setting at least either one of a width of each of the growth regions, a width of each of the growth regions, and the widths Wa, W m1 , and W m2  of the dielectric thin films to vary between semiconductor optical waveguide arrays formed on the substrate.    
     
     
         9 . An array-structured semiconductor optical device including an optical waveguides in an array structure in stripe-shaped growth regions enclosed by dielectric thin films on a substrate, the optical waveguides being fabricated through a selective crystal growth and having a semiconductor multilayer structure including a quantum well layer or a semiconductor multilayer structure including a bulk layer, 
 the optical waveguides being formed a plurarity of optical waveguides in an array structure with an interval therebetween,    the interval being less than a diffusion length of a source material in a reactive tube during the crystal growth.    
     
     
         10 . The array-structured semiconductor optical device in accordance with    claim 9   , wherein the optical waveguides are arranged in an array structure with an interval equal to or less than 50 μm.  
     
     
         11 . The array-structured semiconductor optical device in accordance with    claim 9   , wherein: 
 the optical waveguides are arranged with an interval equal to or less than 10 μm; and    each of the optical waveguides includes side walls, the wall including a (111)B crystal surface selectively grown.    
     
     
         12 . The array-structured semiconductor optical device in accordance with    claim 9   , wherein 
 at least one selected from a band gap energy and a layer thickness of the crystal selectively grown varies between adjacent ones of the optical waveguides.    
     
     
         13 . The array-structured semiconductor optical device in accordance with    claim 9   , wherein 
 the optical waveguides in an array structure include a semiconductor bulk active layer and have a function of an optical amplifier for attaining an optical gain in response to a current injection thereto.    
     
     
         14 . The array-structured semiconductor optical device in accordance with    claim 9   , wherein 
 the optical waveguides in an array structure include a multi-quantum well (MQW) layer and have a light reflection mechanism at both ends of the waveguides or in a proximity thereof,    the waveguides conducting a laser oscillation when an optical gain is attained in response to a current injection thereto.    
     
     
         15 . The array-structured semiconductor optical device in accordance with    claim 9   , wherein 
 the light reflecting function is conducted by a diffraction grating arranged in a proximity of the optical waveguides.    
     
     
         16 . The array-structured semiconductor optical device in accordance with    claim 15   , wherein 
 the diffraction grating has a period varying between adjacent ones of the optical waveguides.    
     
     
         17 . The array-structured semiconductor optical device in accordance with    claim 9   , further including 
 a light spot size converter integrated at least at one end of the optical waveguides.    
     
     
         18 . The array-structured semiconductor optical device in accordance with    claim 9   , further including 
 an optical multiplexer such as a star coupler, a multi-mode interference (MMI) unit at least at one end of the optical waveguides.    
     
     
         19 . A difference-wavelength light source of complex resonator type, comprising: 
 an array-structured semiconductor optical device in set forth    claim 13   ; and    a quartz-based planar lightwave circuit (PLC) including diffraction gratings and the like,    the PLC being integrated with the optical device in a hybrid configuration.    
     
     
         20 . An optical module, comprising at least one array-structured semiconductor optical device in set forth    claim 9   .  
     
     
         21 . An optical communication system, comprising at least one array-structured semiconductor optical device in set forth    claim 9   .