Tunable Transmission Realized with Phase Change Materials

Phase change materials, such as Ge 2 Sb 2 Te 5 (GST), have been extensively explored to realize tunable radiation. However, not too much attention was paid to tunable transmission. In this paper, we propose a tri-layer GST-based planar structure for tuning transmission. It is found that the transmission can be significantly tuned during the phase transition of GST and the difference in transmission can be beyond 0.9 between the amorphous phase and crystalline phase of GST. The physical mechanism is that the Fabry-Perot (FP) resonance can be formed at the amorphous phase of GST, while that cannot be formed at the crystalline phase of GST. Besides, the proposed structure remains excellent performance when the angle of incidence is smaller than 30° under TM polarization. We believe the tunable transmission realized in this work is promising in the application of optical switch and asymmetric transmission.