8E-17 fractional laser frequency instability with a long room-temperature cavity

TL;DR

This paper reports a highly stable laser system using a large, room-temperature optical cavity with advanced thermal and mounting design, achieving fractional frequency instability below 8E-17 over a wide averaging time.

Contribution

The work introduces a novel large optical cavity with sophisticated thermal control and mounting, combined with fiber noise cancellation, to achieve unprecedented laser stability at room temperature.

Findings

Fractional frequency instability below 8E-17 at 1 to 1000 seconds.

Acceleration sensitivity below 2E-10 /g in all directions.

Validation through comparison with other lasers and a strontium clock.

Abstract

We present a laser system based on a 48 cm long optical glass resonator. The large size requires a sophisticated thermal control and optimized mounting design. A self balancing mounting was essential to reliably reach sensitivities to acceleration of below $\Delta \nu / \nu$ < 2E-10 /g in all directions. Furthermore, fiber noise cancellations from a common reference point near the laser diode to the cavity mirror and to additional user points (Sr clock and frequency comb) are implemented. Through comparison to other cavity-stabilized lasers and to a strontium lattice clock an instability of below 1E-16 at averaging times from 1 s to 1000 s is revealed.