$2-\mu$ m Wavelength Grating Coupler, Bent Waveguide, and Tunable Microring on Silicon Photonic MPW

Abstract

The $2-\mu \text{m}$ wave band is emerging as a promising spectral window for optical communications and gas sensing. With the increasing demand for components at this wavelength range, developing $2-\mu \text{m}$ devices is thus required. Silicon photonics is an ideal device technology as it offers several unique advantages of potential low cost and large scale integration. Besides, the silicon nanowire waveguide is transparent and suffers from negligible two photon absorption at $2-\mu \text{m}$ wavelengths. Here, we report the demonstration of grating coupler, waveguide bend, and thermally tunable microring filter on a multi-project wafer which is fabricated using CMOS compatible process. The peak coupling efficiency of the grating coupler is measured to be −8.4 dB at 1952 nm. The bending losses for the rib waveguide and the strip loaded waveguide are measured with different radii. The ring resonator is fabricated and tested with an underestimated $Q$ factor of 1520 (through port) which is due to the limitation of the laser linewidth and wavelength tuning resolution. The extinction ratio exceeds 20 dB and the ring resonance can be thermally tuned by a Titanium Nitride heater. The tuning efficiency is 0.17 nm/mW.