On the enhancement of light absorption in vanadium dioxide/1D photonic crystal composite nanostructures

The absorption behaviors of a 35 nm-vanadium dioxide (VO 2 ) layer grown on top of a 1D photonic crystal (Sio 2 /Si) 10 are investigated theoretically in the near infrared spectral range. VO 2 has an insulator-to-metal phase transition around a critical temperature of 68 °C. The filling fraction (f) is defined as the portion of the VO 2 in the metallic phase—i.e. f = 0 and f = 1 for semiconductor and metal phase, respectively, and 0 < f < 1 during intermediate stages of the transition. Through the transfer matrix method, the influence of the filling fraction on the absorption of the structure has been inspected. It is shown that near-unity absorption can be achieved through VO 2 semiconductor-to-metal phase transition. Moreover, the tunability of absorption at oblique incidence reveals higher values of absorption peaks in the metallic phase of VO 2 than the semiconducting one at each angle of incidence. In addition, there is sensitivity to the state of polarization, so that the absorption peaks for TE mode are higher than the TM case. Finally, adjusting the thickness of the VO 2 layer indicates the possibility of achieving nearly complete absorption in both the semiconductor and metal phases. We believe that these properties make our structure a suitable basis for designing VO 2 -based absorbers.