A 1320 nm experimental optical phase-locked loop

An experimental balanced optical second-order phase-locked loop constructed using 1320 nm diode laser pumped miniature Nd:YAG lasers is discussed. The loop is stable and has a phase error of less than 1.8 degrees when the received signal power is -65 dBm or more. The phase error appears to be dominated by the lasers' frequency noise as long as the signal power is more than -60 dBm.>