Journal of Optics
Temperature insensitivity of a modulated interferometer for determination of phase changes in Raman excitation
Haydee Guadalupe Ochoa, Gustavo Ramírez-Meléndez, Josue Hernandez, E. Gómez
Abstract
Abstract We demonstrate a detection method based on a relative phase detection in two photon Raman excitation. The two Raman beams going through the sample experience a phase change of opposing sign, which appears as a phase shift of their beat note in a fast detector. This signal is compared to a reference one in a microwave interferometer. We show that this way of measuring the phase change in the optical beams displays a very high phase stability that derives from having both beams sharing exactly the same path and being originated from a single laser. This modulated interferometer is at least 18 600 times more immune to temperature variations than a displaced Sagnac interferometer, something that allows for its operation even in the absence of temperature stabilization. The setup maintains full sensitivity to relative phase changes of pairs of beams such as those present in an Electromagnetic Induced Transparency. Using a co-propagating two photon excitation makes it almost insensitive to atomic or molecular motion and gives narrow spectral features.