Intracavity Measurement Sensitivity Enhancement without Runaway Noise

Abstract

A method to increase the sensitivity of an intracavity differential phase measurement that is not made irrelevant by a larger increase of noise is explored. By introducing a phase velocity feedback by way of a resonant dispersive element in an active sensor in which two ultrashort pulses circulate, it is shown that the measurement sensitivity is elevated without significantly increasing the Petermann excess noise factor. This enhancement technique has considerable implications for any optical phase based measurement; from gyroscopes and accelerometers to magnetometers and optical index measurements. Here we describe the enhancement method in the context of past dispersion enhancement studies including the recent work surrounding non-Hermitian quantum mechanics, justify the method with a theoretical framework (including numerical simulations), and propose practical applications.

Control of Frequency Combs with Passive Resonators

“…It has been shown that the sensitivity of such sensors is proportional to the mode spacing of the comb, mode spacing that can be tens of GHz through the insertion of an etalon in the cavity [ 21 ]. Furthermore, because of the comb modes being rigorously equally spaced [ 5 , 28 , 29 ], the resonant dispersion of each Fabry–Perot mode is pasted onto the whole comb structure, resulting in an enhancement of the sensor response [ 22 ].…”

“…Depending on its sign, the resonant dispersion affects the phase velocity of the intracavity pulses circulating in the laser, resulting in“fast” or “slow” light. The “fast” light enhances the phase sensitivity of a sensor [ 20 , 21 , 22 , 23 ].…”