Options of optical voltage-controlled oscillator for subcarrier optical phase-locked loop

Abstract

A comprehensive study of an optical voltage-controlled oscillator (OVCO) is presented. With the help of analyzing the coherent receiving process for the binary phase-shift keying signal in a Costas subcarrier optical phase-locked loops system, the method to evaluate the OVCO performance based on calculating the transfer function of the modulator inside the OVCO is proposed, including the power efficiency and the requirement for received signal bandwidth. In addition, three possible OVCO configurations realized by Mach–Zehnder modulator, IQ modulator, and phase modulator are presented. The means to achieve the optimal performance of the OVCO configurations in practical implementations are theoretically explained, respectively, and their properties and the complexity are summarized. This work provides useful theoretical guides for the OVCO design in a lab experiment or for the production of a commercially integrated OVCO component.