Demonstration of a Transportable 1 Hz-Linewidth Laser

TL;DR

This paper demonstrates a transportable 1 Hz-linewidth laser system for atomic clocks, showing it maintains performance after transportation over 400 km, enabling portable high-precision timekeeping.

Contribution

It introduces a transportable, cavity-stabilized laser system with verified stability after long-distance transport, suitable for portable atomic clock applications.

Findings

Laser linewidth below 1 Hz maintained after transport

Transport did not degrade laser performance

Successful comparison with stationary clock laser

Abstract

We present the setup and test of a transportable clock laser at 698 nm for a strontium lattice clock. A master-slave diode laser system is stabilized to a rigidly mounted optical reference cavity. The setup was transported by truck over 400 km from Braunschweig to D\"usseldorf, where the cavity-stabilized laser was compared to a stationary clock laser for the interrogation of ytterbium (578 nm). Only minor realignments were necessary after the transport. The lasers were compared by a Ti:Sapphire frequency comb used as a transfer oscillator. The thus generated virtual beat showed a combined linewidth below 1 Hz (at 1156 nm). The transport back to Braunschweig did not degrade the laser performance, as was shown by interrogating the strontium clock transition.