Thermally induced tuning of absorption in a Ge2Sb2Te5-based one-dimensional Fibonacci quasicrystal

Tunable absorption features are theoretically investigated in a symmetrical Fibonacci (FB) structure hybridized with a 40 nm-Ge2Sb2Te5 (GST) film in the near-infrared region. GST is one of the most prominent phase change materials whose optical properties can drastically change during its phase transition from an amorphous to a crystalline structure. In particular, its non-volatile behavior which makes it a stable material in either phase for years, is of great importance in optoelectronics. Indeed, we utilize the phase switching of GST via the thermooptical effect to engineer a tunable absorbing device. Our results show a high contrast in the absorption levels between the amorphous and crystalline states of GST for the proposed structure. Considering the sixth FB generation, for example, the amorphous-to-crystalline phase transition of GST changes the absorption value from nearly zero to similar to 0.9 under a TE-polarized wave at an angle of incidence of 45 degrees. We can also achieve enhanced absorption in amorphous GST with the appropriate choice of parameters. Consequently, the structure can be reconfigured from nearly transparent to absorbent and vice versa. This work suggests a promising approach for designing tunable temperature-assisted GST-based absorbers and optical switching devices.