High resolution, high channel count mid-IR AWGs in silicon

Arrayed waveguide gratings (AWGs) working in the 4.7 µm wavelength range are reported on silicon-on-insulator waveguides with 1500 nm thick silicon and 2 µm thick buried oxide layers. For eight channel devices, three different channel spacings (200 GHz, 100 GHz, and 50 GHz) with cross talk levels of −32.31dB, −31.87dB, and −27.28dB and insertion loss levels of −1.43dB, −4.2dB, and −2.3dB, respectively, are demonstrated. Fourteen channel AWGs with 170 GHz channel spacing and 16 channel AWGs with 87 GHz channel spacing are shown to have a cross talk value of −21.67dB and −24.30dB and insertion loss value of −4.2dB and −3.8dB, respectively. Two AWGs with 10 nm difference in channel peak are designed, and the measurements show a 9.3 nm difference. The transmission spectrum shift as a function of temperature is found to be 0.22 nm/°C.