Optical parametric wideband frequency modulation

Abstract

Various types of photonic applications, such as sensing and communication, require the generation of wideband optical frequency-modulated (FM) signals. However, generating a wideband FM signal beyond the electrical bandwidth limitation of optical modulators is difficult. Here, we propose a method to increase the bandwidths of optical FM signals by using the cascaded four-wave-mixing (FWM) process and show its potential in two applications. We first demonstrate 11-fold bandwidth expansion of frequency-modulated continuous-wave signals (from 5 to 55 GHz), beyond the optical modulator bandwidth. Next, we demonstrate the signal-to-noise ratio (SNR) enhancement for analog communication. The SNR of an analog signal can be increased by ∼12.8 dB using the proposed method. These results show the potential of the proposed method for sensing and communication applications. In addition, the proposed concept opens new possibilities in parametric FWM applications.