Back-End Integration of Multilayer Photonics on Silicon

We present vertically-stacked a-Si.:H and AlN photonic circuits deposited on silicon using back-end CMOS technology. At 1550-nm telecom wavelengths, the a-Si:H (0.5-mu mx0.22-mu m) and AIN (1-mu mx0.4-mu m) channel waveguides are measured to have low propagation losses of similar to 3.8 and similar to 1.4 dB/cm, respectively. Various passive devices with high performance are demonstrated on these two photonic layers, including multimode interferences (MM1), waveguide ring resonators (WRR), and arrayed-waveguide gratings (AWG). Moreover, the thermo-optic coefficients (dn/dT) of a-Si:H and AlN are measured to be similar to 2.60x10(-4) and similar to 3.56x10(-5) K-1, respectively.