Receiver optical sub-assembly, multi-channel receiver optical sub-assembly, and operating method thereof

A multi-channel optical receiver sub-assembly comprising:

• a plurality of optical receiver sub-assemblies arranged by channel units,
• wherein each of the plurality of optical receiver sub-assemblies comprises:
• a substrate;
• an optical waveguide device mounted on the substrate to transfer ray incident from a ray source;
• and
• a photodetector mounted on the substrate and disposed under a vertical cross-sectional surface of the optical waveguide device,
• wherein the ray is reflected and refracted by an upper slope surface and a lower slope surface provided in the vertical cross-sectional surface and is vertically incident on an active area of the photodetector.

An operating method of an optical receiver sub-assembly, the operating method comprising:

• a step of irradiating ray from a ray source onto an optical waveguide device;
• a step of reflecting the irradiated ray by using an upper slope surface provided in a vertical cross-sectional surface of the optical waveguide device;
• a process of refracting the ray reflected by the upper slope surface by using the lower slope surface provided in the vertical cross-sectional surface of the optical waveguide device;
• and
• a step of vertically irradiating ray refracted by the lower slope surface onto an active area of a photodetector disposed under the vertical cross-sectional surface.