Improved optically SILPLL based forced oscillators

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.