Polarization-diverse coherent optical spectrum analyzer with swept local oscillator

We demonstrated, for the first time, a polarization diverse coherent optical spectrum analyzer based on a continuously tunable local oscillator (LO). A resolution of 20 MHz (∼0.00016 nm) and a 60 dB dynamic range were demonstrated. The instrument employs a pseudo-depolarized LO to provide polarization diverse reception. The balanced receiver architecture makes the low-frequency IF operation possible and shows a sufficient level of intensity noise subtraction for the spectral measurements of intensity-modulated lasers.