SSO Seminar
Wednesday, March 11, 2015 - 16:00 to 17:00
Weniger 304
Event Speaker: 
Prof. Shannon O'Leary
Local Contact: 
David McIntyre

One might naively assume that unavoidable fluctuations in laser frequency, intensity, and phase are always undesirable in experimental applications. But light-matter interactions can encode useful information about the medium in the transmitted light’s fluctuations, and analysis of these fluctuations can actually enhance measurement precision in some cases. In particular, it is well known that free-running diode lasers have significant phase noise and that a resonant atomic vapor will convert phase noise into transmitted intensity noise. A true, but less well-known fact is that intensity noise from orthogonally polarized laser field from the same laser source can be either correlated or, rather surprisingly, anti-correlated depending very sensitively on detuning from a resonance. In this talk I will present noise correlation studies using a single “noisy” diode laser interacting with rubidium vapor on a sharp resonance feature from atomic coherence, namely Electromagnetically Induced Transparency (EIT) in the Hanle configuration. Of particular interest is a narrow band of perfect correlation that coincides with EIT. The linewidth of this noise correlation peak has been shown to be power-broadening resistant at low laser powers. I will present recent experimental noise correlation studies, including power broadening of this correlation peak at higher powers. This noise correlation technique holds promise in high-resolution applications such as atomic EIT-noise magnetometry.