Abstract

The 2-μm waveband has gained much attention due to its potential applications in data communications and optical sensing. This wavelength range is of particular interests for integrated platform as it is transparent for silicon and is free of two photon absorption. We experimentally demonstrate a 2- μm silicon focusing grating coupler with subwavelength structure. The theoretical coupling efficiency for TM polarization is simulated to be 48% with 10 degrees tilt angle at 1952 nm. The measured peak coupling efficiency is 24.3% with the coupling angle of 11°. The grating coupler at two micron spectral band provides an efficient interface between the light source and the 2-μm photonic integrated circuits.

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