Enhanced electro-optical effect in silicon

Abstract

We demonstrate methods to enhance electro-optical effect in silicon. In the first method, a tunable PhC device is proposed to consist of the self-guiding region and the tunable region. The tunable lattice is designed such that it has a band gap and the self-guiding frequency is located at its bottom band edge of the conduction band. Therefore, the device output can be tuned by injecting free carriers into the tunable region to slightly reduce its effective index to pull up the band gap. In the second method we design a self-guiding PhC cavity. Using this cavity, we could switch output light on and off with an extinction ratio of 17.5 dB by changing only 1e-3 of the effective refractive index of the silicon background. The third method utilizes a 12-fold symmetric quasi- photonic crytal cavity to enhance electro-optical effect in silicon. The designed cavity supports whispering gallery modes and one of such modes is found to have Q value of 2.3e4.