The present invention relates to a semiconductor integrated light emitting device in which a light emitting device and an external waveguide are integrated on the same semiconductor substrate and, more particularly, to a structure for coupling a light emitting waveguide of the light emitting device with an external waveguide.
Semiconductor lasers and similar semiconductor light emitting devices have such features as small size, high efficiency and high reliability, and are now widely used in the fields of optical fiber communication and optical information processing; in particular, they are at the core of technology in the field of optoelectronics. On the other hand, enlargement and sophistication of the optoelectronics technology are now in progress, and it is essential to develop semiconductor integrated light emitting devices of the types wherein an external waveguide for modulation use is integrated with the light emitting device, wherein a grating external waveguide is integrated with the light emitting device to constitute a distributed Bragg reflector (hereinafter referred to simply as "DBR") laser, and wherein a modulating feature is additionally provided on an extension of the grating external waveguide.
In the integration of the light emitting device and the external waveguide on the same substrate, what is important technically and in terms of manufacture as well is how to implement the optical coupling between the light emitting waveguide of the light emitting device and the external waveguide.
Of methods proposed so far for optically coupling the both waveguides with each other, a direct coupling method which directly connects them at one end thereof is considered as the most promising because of high coupling efficiency and low allowable limits of manufacturing errors, and actually this method is now under study for practical applications.
However, devices of good operational performance and ready for manufacturing have not yet been proposed by the prior art.