Thermal Properties of Optomechanical Photonic Crystals

Abstract

In many fields such as electronics or photonics, thermal effects play a significant role in the overall functioning of the devices. Therefore, it is important to understand and quantify their impact. In this work, we study these effects in a specific type of photonic device, namely a one-dimensional photonic crystal, which is at the same time a collection of mechanical resonators. Specifically, we investigated the dominant dissipation mechanism in nanopillars heated by the electromagnetic field, considering 2 different types of nanopillars: the full silicon cell (FSC) and SiO2 cell (SiO2C). Initially, we obtained the optical modes to acquire the spatial electric field distribution to use as the heat source in the nanopillars. The first study involved heating with the electric field distribution at 195.96 THz. The decay rates obtained were: 1/τSi = 7.67 MHz and 1/τSiO2 = 2.22 MHz. Subsequently, we studied the decay rates as the radius of the structures decreased. For FSC, the decay rate decreased, whereas for SiO2C, it increased. Aditionally, we calculated the dissipation process for another electric field distribution (230.99 THz). The decay rates obtained were slightly lower than the first study, 1/τ′ Si = 7.40 MHz and 1/τ′ SiO2 = 1.99 MHz. Finally, we compared the values from the first study to experimental values. The experimental value for FSC was 29.63% higher, while for SiO2C, the simulated value was 9.90% higher. We concluded that the dominant dissipation mechanism for FSC is conduction due to dissipation through the bottom silicon pillar. In contrast, for SiO2C, the dominant dissipation mechanism is convection, as thermal transport through the bottom SiO2 pillar is negligible.