Phase Noise Power Spectral Density Measurement of Narrow Linewidth CW Lasers Using an Optical Phase-Locked Loop

A novel technique for continuous-wave (CW) laser phase noise power spectral density measurement, useful for coherent communications, is proposed. It employs a homodyne optical phase-locked loop. Experimental results are compared with a self-heterodyne linewidth measurement and the comparison shows how the proposed measurement method gives more accurate results for coherent transmission system applications