Fig. 1. Principle diagram of optical switch based on PCM. (a) Three-dimensional structural diagram of an optical switch based on In₂Se₃; (b) schematic of coupling region of optical switch; (c) view of top-level optical coupling based on In₂Se₃; (d) cross-sectional view of coupling waveguide

Fig. 2. Effective refractive index of silicon waveguide and heterostructure integrated waveguide. (a) Curve of effective refractive index of TE0 mode in silicon waveguide varying with the width of silicon waveguide; simulated dependence of (b) real partneffand (c)imagine part keffof the effective refractive index and Si-In2Se3 hybrid waveguide at λ=1550 nm by varying the height

Fig. 3. Distribution of electric field intensity E in heterogeneous integrated waveguide. (a) Thickness of α-In₂Se₃ is 30 nm; (b) thickness of β-In₂Se₃ is 25.5 nm; (c) thickness of α-In₂Se₃ is 45 nm; (d) thickness of β-In₂Se₃ is 38.25 nm; (e) thickness of α-In₂Se₃ is 60 nm; (f) thickness of β-In₂Se₃ is 51 nm

Fig. 4. Distribution of electric field intensity E of double waveguide system in even supermode state and odd supermode state. (a) (b) Thickness of α-In₂Se₃ is 30 nm; (c) (d) thickness of β-In₂Se₃ is 25.5 nm; (e) (f) thickness of α-In₂Se₃ is 45 nm; (g) (h) thickness of β-In₂Se₃ is 38.25 nm; (i) (j) thickness of α-In₂Se₃ is 60 nm; (k) (l) thickness of β-In₂Se₃ is 51 nm

Fig. 5. Transmission spectra of optical switching devices when gap between two waveguides is 0.1 μm. (a) Graph of transmittance of optical switching device in α-In2Se3 and β-In2Se3 states with coupling length of waveguide; (b) transmission spectra of two output ports at α-In2Se3 and β-In2Se3 (thickness of α-In2Se3 is 30 nm, and thickness of β-In2Se3 is 25.5 nm)

Fig. 6. When In2Se3is in α state and β state, light transmission in the directional coupler. (a) When In2Se3is in α state, most of light energy is output from cross port because phase matching condition is met, thickness of α-In2Se3 is 30 nm; (b) when In2Se3is in β state, most of light energy is output from bar port because phase matching condition is not met, thickness of β-In2Se3 is 25.5 nm; (c) when In2Se3is in α state, most of light energy is output from cross port because phase matching condition is met, thickness of α-In2Se3 is 45 nm; (d) when In2Se3is in β state, most of light energy is output from bar port because phase matching condition is not met, thickness of β-In2Se3 is 38.25 nm; (e) when In2Se3is in α state, most of light energy is output from cross port because phase matching condition is met, thickness of α-In2Se3 is 60 nm; (f) when In2Se3is in β state, most of light energy is output from bar port because phase matching condition is not met, thickness of β-In2Se3 is 51 nm

Fig. 7. When In2Se3 is in α state and β state, curves of IL and CT of device with wavelength variation. (a) When In2Se3 is in α state, graph of change of IL with wavelength of device; (b) when In2Se3 is in β state, graph of change of IL with wavelength of device; (c) when In2Se3 is in α state, graph of change of CT with wavelength of device; (d) when In2Se3 is in β state, graph of change of CT with wavelength of device (thickness of α-In2Se3 is 30 nm,45 nm, and 60 nm, respectively, and thickness of β-In2Se3 is 25.5 nm,38.25 nm, and 51 nm, respectively)