Design of quasi-one-dimensional phononic crystal cavity for efficient photoelastic modulation

Abstract

We propose and design a phononic crystal (PnC) cavity for efficient photoelastic modulation. A strongly confined acoustic field in the cavity enhances light-sound interaction, which results in efficient phase modulation of light. As one of the possible configurations, an acoustic cavity formed in a quasi-one-dimensional (quasi-1D) PnC was investigated. By carefully tuning geometrical parameters, we successfully designed a high-Q cavity mode for a longitudinal wave within a complete phononic band gap. The acoustic Q was calculated to be as high as 9.5 ' 104. This enables efficient optical modulation by a factor of 2.5 compared with a bar-type structure without PnCs.