High resolution phase demodulation at 1530nm using low-pressure acetylene absorption lines

摘要

We present results of an experimental investigations of the noise characteristics of a self-referencing optical phase demodulator, based on a bulk low-pressure acetylene cell at the wavelength 1530.37nm of P9 absorption line. The configuration under investigation is simple, does not need phase locking and can be operated with the high-etandue waves. While the intensity noise of the utilized semiconductor laser at frequency >250MHz was below the photonic noise, the demodulator resolution (i.e. the minimum detectable phase modulation amplitude) was significantly reduced by an excessive laser phase noise. To reduce the output noise we propose and analyze different balanced detection configurations that increase the resolution to the standard quantum level.