A modulation–demodulation scheme substantially enhances diffusion-dominated–adaptive-interferometric sensitivity. The path length sensitivity is improved by converting a quadratic small-signal response, easily drowned in system noise, to a linear response by mixing with a strong phase modulation. This conversion also shifts low-frequency signals away from
noise. Experimental results show
displacement sensitivity for a
signal with a few milliwatts of optical power, an improvement of 3 orders of magnitude over the unenhanced system.
© 2007 Optical Society of America
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