Ultracompact silicon optomechanical cavities as optical upconverters of OFDM wireless signals

Silicon optomechanical (OM) cavities have been presented as relevant elements in microwave photonics and optical RF processing, particularly in applications requiring low-weight and compactness. In this work, we introduce and demonstrate a new functionality by employing a silicon OM crystal cavity operated in the phonon lasing regime for optical upconversion of a radio-frequency data signal employing orthogonal frequency division multiplexing (OFDM) modulation. The OM crystal cavity is created on suspended silicon nano-beams with one-dimensional (1D) periodicity with <10μm2 foot-print. The proposed OM crystal cavity operates as an optoelectronic oscillator at the GHz regime, with a low phase noise for the first harmonic at 3.9 GHz in the self-sustained oscillation regime. The OM crystal cavity characterization indicates that the optical resonance is centered at 1541.2±0.3 nm with a loaded optical quality factor Qo ≈ 4×103. Using such cavity we demonstrate successful upconversion of full-standard IEEE 802.16e WiMAX signals employing OFDM with QPSK modulation per-carrier over different bandwidths.