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Free keywords:
Physics, Optics, physics.optics, Physics, Instrumentation and Detectors, physics.ins-det
Abstract:
To achieve sub-picometer sensitivities in the millihertz band, laser
interferometric inertial sensors rely on some form of reduction of the laser
frequency noise, typically by locking the laser to a stable frequency
reference, such as the narrow-linewidth resonance of an ultra-stable optical
cavity or an atomic or molecular transition. In this paper we report on a
compact laser frequency stabilization technique based on an unequal-arm
Mach-Zehnder interferometer that is sub-nanometer stable at $10\,\mu$Hz,
sub-picometer at $0.5\,$mHz, and reaches a noise floor of
$7\,\mathrm{fm}/\!\sqrt{\mathrm{Hz}}$ at 1 Hz. The interferometer is used in
conjunction with a DC servo to stabilize the frequency of a laser down to a
fractional instability below $4 \times 10^{-13}$ at averaging times from 0.1 to
100 seconds. The technique offers a wide operating range, does not rely on
complex lock acquisition procedures, and can be readily integrated as part of
the optical bench in future gravity missions.
