Fig. 1. (a) All-optical phase shifter and switch based on WS2-deposited tapered fiber. (b) TEM image of WS2 nanosheets. (c) Microscopic image of WS2-deposited tapered fiber. (d) Raman spectrum of WS2-deposited tapered fiber. Adapted with permission from Ref. [39].

Fig. 2. (a) Transmission spectra of the MZI with 0 (blue) and 5π phase shift (red). (b) Relation between the phase shift and the control light power. (c) Pulsed control light (yellow) and switch output at output 1 port (blue). (d) Complementary output at output 2 port. Adapted with permission from Ref. [39].

Fig. 3. (a) Refractive index of WS2 from ellipsometric measurement and (b) refractive index change at different temperatures. Adapted with permission from Ref. [39].

Fig. 4. (a) All-optical switch based on polarization interferometer and MoS2-PVA thin film. (b) MoS2-PVA thin film. (c) Device principle. Adapted with permission from Ref. [40].

Fig. 5. (a) Pulsed control light (yellow) and output signal (blue). (b) A zoomed view of a single off–on–off transition of the output pulse (blue) and exponential fit (red). (c) A long-term stable output pulse train. Adapted with permission from Ref. [40].

Fig. 6. (a) All-optical switch based on a graphene-on-Si3N4 device. (b) Device structure. (c) SEM image of device. (d) Device principle. Adapted with permission from Ref. [41].

Fig. 7. Experimental (black) and simulation (red) results of an output signal pulse. Inset: temperature change of the device. Adapted with permission from Ref. [41].

Fig. 8. (a) Mode distribution in a single-mode fiber. Relation between (b) index change and core index change, and (c) index change and cladding index change.

Table 1. Comparison of Reported Works of Thermo-Optic All-Optical Switches Based on 2D Materials