Subwavelength grating couplers for efficient light coupling into silicon nanomembrane based photonic devices

Abstract

We demonstrate efficient coupling of light into silicon nanomembrane (SiNM) based photonic devices using a subwavelength grating (SWG) coupler. Our designed 17.1 μm x 10 μm grating couplers are fabricated at the input and the output of 8 mm x 2.5 μm SiNM waveguides on a glass substrate. A high coupling efficiency of 39.2% is achieved at a wavelength of 1555.56 nm. The 1-dB and 3-dB bandwidths are measured to be 29 nm and 57 nm, respectively. Peak efficiency variation of 0.26 dB is observed from a measurement of 5 grating pairs. Such grating couplers open limitless possibilities for the development of high performance nanomembrane based photonic devices.