Thermo-optic tuning of silicon nitride microring resonators with low loss non-volatile hbox {Sb}_{2}hbox {S}_{3} phase change material

Abstract

A new family of phase change material based on antimony has recently been explored for applications in near-IR tunable photonics due to its wide bandgap, manifested as broadband transparency from visible to NIR wavelengths. Here, we characterize hbox {Sb}_{2} hbox {S}_{3} optically and demonstrate the integration of this phase change material in a silicon nitride platform using a microring resonator that can be thermally tuned using the amorphous and crystalline states of the phase change material, achieving extinction ratios of up to 18 dB in the C-band. We extract the thermo-optic coefficient of the amorphous and crystalline states of the hbox {Sb}_{2}hbox {S}_{3} to be 3.4 x 10^{-4}hbox {K}^{-1} and 0.1 x 10^{-4}hbox {K}^{-1}, respectively. Additionally, we detail the first observation of bi-directional shifting for permanent trimming of a non-volatile switch using continuous wave (CW) laser exposure (-5.9 to 5.1 dBm) with a modulation in effective refractive index ranging from +5.23 x 10^{-5} to -1.20 x 10^{-4}. This work experimentally verifies optical phase modifications and permanent trimming of hbox {Sb}_{2}hbox {S}_{3}, enabling potential applications such as optically controlled memories and weights for neuromorphic architecture and high density switch matrix using a multi-layer PECVD based photonic integrated circuit.