Further Examination of the Injection-Locked Dual Optoelectronic Oscillator

Abstract

Optoelectronic oscillators (OEO), utilizing the low loss nature of optical links, can generate oscillations with very high Q values. The long delay line used in the oscillator can, however, support many modes of oscillation. Mode spacing is inversely proportional to the delay length of the optical link. The oscillator Q can be improved by increasing the delay length at the expense of tighter mode spacing. The undesirable modes become more difficult to filter in the RF domain as the spacing becomes closer. There are many different techniques for minimizing the impact of the competing modes on the desired one. The injection-locked dual OEO was presented last year. It consists of a high-Q multimode OEO (master) and a low-Q single-mode OEO (slave), each injection-locked to each other. The slave OEO, which generates the output signal, is injection-locked to the master OEO. This transfers some of the high-Q stability to the output, without transferring all of the spurious competing modes of the master. The master is also injection-locked to the slave OEO, causing its multimode oscillation to collapse to a mostly single mode, further reducing the transfer of spurious modes to the slave. In this paper we analyze the injection lock parameter's behavior on the performance of the total system.