The effect of input phase modulation to a phase-sensitive optical amplifier

摘要

Many optical applications depend on amplitude modulating optical beams usingdevices such as acousto-optical modulators (AOMs) or optical choppers. Methodsto add amplitude modulation (AM) often inadvertently impart phase modulation(PM) onto the light as well. While this PM is of no consequence to manyphase-insensitive applications, phase-sensitive processes can be affected. Herewe study the effects of input phase and amplitude modulation on the output of aquantum-noise limited phase-sensitive optical amplifier (PSA) realized in hot$^{85}$Rb vapor. We investigate the dependence of PM on AOM alignment anddemonstrate a novel approach to quantifying PM by using the PSA as a diagnostictool. We then use this method to measure the alignment-dependent PM of anoptical chopper which arises due to diffraction effects as the chopper bladepasses through the optical beam.