fig4

Figure 4. (A) A schematic of the PCM-decorated photonic waveguide. The PCM thickness h_PCM and PCM length d_PCM being 10 nm and 1 μm, respectively; (B-D) The transmittance spectra of waveguides vs. Se substitution of GST with rs-, o- and a-phase at the telecommunication bands (1,500-1,600 nm) from FDTD simulations. The calculated optical data were used to describe the optical response of GST and Ge₂Sb₂Se_xTe_5-x (x = 0 to 4); (E) The transmittance contrast (ΔT) of waveguides between the rs-phase and the a-phase; (F) ΔT of waveguides between the o-phase and the a-phase. PCM: Phase-change material; GST: Ge₂Sb₂Te₅; FDTD: finite-difference time-domain.