Optical semiconductor device and optical semiconductor integrated circuit

Abstract

An optical semiconductor device and optical semiconductor integrated circuit are provided by combining, on a semiconductor substrate, materials having different refractive indices and different temperature dependence of the refractive indices. In particular, it becomes possible to control the temperature dependence of the oscillation wavelength with a propagating region having a material and / or structure whose temperature dependence of the refractive index is different from that of a gain region of the semiconductor laser. In addition, they can be configured to have a plurality of interfaces formed along the waveguide direction of the optical waveguide so that the light reflected off the first interface is weakened by the light reflected from the remaining interfaces. Also, they can be configured with the interfaces inclined to the propagating direction so that the waveguide loss due to the reflection and refraction between the optical waveguides whose refractive indices differ from each other can be reduced.

Description

technical field [0001] The present invention relates to optical semiconductor elements such as semiconductor lasers, optical waveguides, and other optical devices, and optical semiconductor integrated circuits, and more particularly to optical semiconductor elements in which materials having different refractive indices and temperature dependencies of refractive indices are combined on a semiconductor substrate and optical semiconductor integrated circuits. Background technique [0002] The vibration wavelength of semiconductor lasers changes with ambient temperature and element temperature. For example, as published by K.Sakai, "1.5μm range InGaAsP / InP distributed feedback lasers," IEEEJ.Quantum Electron., vol.QW-18, pp.1272-1278, Aug.1982, the distributed feedback type (DFB) laser The dependence of the vibration wavelength on temperature is about 0.1nm / K. This is due to the temperature dependence of the refractive index (n) of the semiconductor, so the Bragg wavelength (...

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Problems solved by technology

[0024] However, when a semiconductor optical waveguide is coupled to an optical waveguide made of a material having a different refractive index from the semiconductor optical waveguide, the degree of freedom in waveguide design is limited due to reflection at the bonding interface corresponding to the difference in refractive index.

[0025] where by using the Brewster angle θ B , the reflection between waveguides with different refractive indices can be reduced, but using the Brewster angle θ B If the light is refracted at the boundary surface between the waveguides, there is a problem that the waveguide direction becomes not a straight line.

[0026] In addition, Brewster's angle θ is used to reduce reflection between waveguides with different refractive indices. B If this is the case, it becomes difficult to fabricate a buried semiconductor waveguide along a specific crystal direction, and there is a problem that a buried semiconductor waveguide cannot be fabricated with high reliability.

[0027] Furthermore, if Brewster's angle θ is used to reduce reflection between waveguides with different refractive indices, B If this is the case, it is difficult to arrange the semiconductor waveguide perpendicular to the cleavage plane, and there is a problem that the cleavage plane cannot be used as a reflection surface of a semiconductor laser or the like.

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