Improved optically SILPLL based forced oscillators

Abstract

High stability oscillators are required for many RF applications. Phase noise reduction of voltage controlled oscillator (VCO) using different forced oscillation, such as self-injection locked, self-phase locked loop, and their combination as a self-Injection locked phase locked loop, has been reported, where optical delay lines are employed with low relative intensity noise (RIN) laser sources to entrain oscillation frequency. Performance comparisons between a DFB laser and a fiber laser as optical delay line sources in various forced oscillation topologies. Phase noise performance of -109dBc/Hz at offset frequency 1 kHz is achieved in SILDPLL topology using the fiber laser as optical source, which is a 5dB lower in SSB phase noise performance than the one measured using the DFB laser.