Fork Type Structure of Silicon Waveguide for Optical Efficiency Optimization

Abstract

The coupling interface between optical fiber and photonics chip waveguide is critical for optical coupling efficiency. Grating coupling offers better fiber mis-alignment tolerance, but it was limited by narrow coupling bandwidth which might not able to meet wavelength-division multiplexing requirement. Edge coupling offers broad bandwidth capability but suffers lower coupling efficiency (C.E.) for hifher fiber mis-alignment tolerance. In order to obtain high coupling efficiency and broad coupling bandwidth, we proposed multiple taper waveguide design for edge coupling PIC application. In this design, using two tapers with splitter waveguide, it enhances the overall coupling efficiency but not increase the complexity of the assembly process. According to simulation result, 1.5 dB higher coupling efficiency was obtained than traditional single taper design which is also able to accommodate higher fiber alignment tolerance. It is easily to be implemented in current commercial silicon photonics CMOS technology and can be worked with single mode fiber to provide better coupling efficiency and higher mis-alignment tolerance