A Symmetric Parity–Time Coupled Optoelectronic Oscillator Using a Polarization–Dependent Spatial Structure

Abstract

We propose and experimentally investigate a symmetric parity-time (PT) coupled optoelectronic oscillator (COEO) based on a polarization-dependent spatial structure. In such a COEO system, the gain/loss and coupling coefficients of two orthogonal polarization optical waves can be controlled by adjusting the polarization controller (PC) and the bias voltage of a Mach-Zehnder modulator (MZM). The single-mode selection of a microwave signal can be implemented by the PT symmetry breaking of a special mode. The performance of the proposed COEO is experimentally examined, and a 10.0 GHz microwave signal with a phase noise of −109.1 dBc/Hz @ 10 kHz and a side mode suppression ratio of 51.4 dB is generated. Moreover, an optical frequency comb with a comb tooth spacing of 10.0 GHz and a bandwidth of 100 GHz within a 10 dB amplitude variation can be simultaneously generated.

High-Performance Fiber Ring Laser Based on Polarization Space Parity-Time Symmetry Breaking

“…Here, the PBS can be effectively regarded as a linear polarizer. The relations between the electric fields before and after passing through the concatenated combination of PC1 and PBS for one round trip inside the cavity, denoted as E 0 and E 1 , can be expressed as [23,29]: In Figure 1a, the birefringence of PC1 induces two polarization components, E x and E y . The angle between the electric field vector E x and the parallel polarization direction in the PBS, denoted as θ, can be controlled through PC1.…”

“…Here, the PBS can be effectively regarded as a linear polarizer. The relations between the electric fields before and after passing through the concatenated combination of PC1 and PBS for one round trip inside the cavity, denoted as E 0 and E 1 , can be expressed as [23,29]:…”