A novel spot size convertor for hybrid integrated light sources on photonics-electronics convergence system

We have developed a spot size converter (SSC) with a trident silicon (Si) waveguide for the hybrid integrated light source in a photonics-electronics convergence system. Low loss coupling was achieved with just the simple planar form of a Si waveguide with no use of complicated structures such as vertical tapers or extra dielectric core overlaid on the waveguide. The coupling loss was 2.3 dB and the tolerance of misalignment up to a 1-dB loss increase was about ± 0.9 μm. We also confirmed that the coupling efficiency was quite robust against manufacturing fluctuations of the waveguide width compared with a conventional SSC with an inverse taper waveguide. We were able to fabricate a 52-channel light source with highly uniform output power by using the proposed trident SSC.