Ultra-compact, ultra-low-loss and broadband 2x2 nonvolatile optical switch based on Sb2Se3 phase change material

We propose an ultra-compact broadband 2 x 2 nonvolatile optical switch based on two adjacent silicon waveguides embedded with a low-loss phase change material (Sb2Se3). In the crystalline state of Sb2Se3, the two waveguides in the middle section are not coupled, and meanwhile they have a pi phase difference. Consequently, the structure functions as a Mach-Zehnder interferometer, and the optical switch operates in the bar state, achieving insertion loss of 0.068 dB and crosstalk of-31.97 dB at wavelength 1550 nm. In the amorphous state, this structure serves as a three-stage directional coupler, and the optical switch operates in the cross state, achieving insertion loss of 0.034 dB and crosstalk of-29.27 dB at 1550 nm. The footprint of the optical switch is as small as ' 3.6 x 27.6 mu m(2), and the length of Sb2Se3 is only 1.63 mu m, resulting in ultra-low loss over a large wavelength range. It is found that the insertion loss of optical switch is less than 0.17 dB, while the crosstalk is less than-15 dB, within a bandwidth broader than 64 nm. Furthermore, the simulations reveal that the device exhibits high tolerance to fabrication errors. Owning to the compactness, ultra-low loss and broadband, our nonvolatile optical switch has bright application prospects in advanced photonic integrated circuits. (c) 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement