All-fiber-based ultrastable laser with long-term frequency stability of 1.1 × 10-14

Abstract

We demonstrate an ultrastable miniaturized transportable laser system at 1550 nm by locking it to an optical fiber delay line (FDL). To achieve optimized long-term frequency stability, the FDL was placed into a vacuum chamber with a five-layer thermal shield, and a delicate two-stage active temperature stabilization, an optical power stabilization, and an RF power stabilization were applied in the system. A fractional frequency stability of better than 3.2 × 10 −15 at 1 s averaging time and 1.1 × 10 −14 at 1000 s averaging time was achieved, which is the best long-term frequency stability of an all-fiber-based ultrastable laser observed to date.

Fiber-coupled 2 mL vacuum-gap Fabry–Perot reference cavity for portable laser stabilization

“…While vacuum-gap Fabry-Pérot cavities boast lower thermal noise than the best dielectric frequency references, they typically require free-space coupling optics and bulky vacuum hard-ware, significantly increasing overall system size, weight, and 16 power consumption (SWaP). Fiber-optic [8][9][10] and waveguide-17 based systems [11,12] have been used to demonstrate compact 18 and integrable frequency references. However, the thermorefrac-19 tive noise and long term thermal drift inherent to these dielectric 20 resonators provide fundamental limitations that tend to lead to 21 higher instability [13] and impose stricter requirements on the 22 necessary degree of environmental isolation.…”