Shifts of optical frequency references based on spectral-hole burning in Eu:Y2SiO5

TL;DR

This paper evaluates Eu:Y2SiO5 spectral holes as stable optical frequency references by measuring their responses to magnetic fields, neighboring spectral features, and temperature changes, including a calibration point with minimal temperature sensitivity.

Contribution

It provides new measurements of spectral hole shifts under various conditions and identifies a temperature-insensitive point for improved frequency stability.

Findings

Magnetic field causes measurable frequency shifts.

Neighboring spectral holes influence frequency stability.

A temperature-insensitive point is calibrated for better reference stability.

Abstract

Several properties of Eu:Y2SiO5 spectral holes are measured, to assess the suitability of broad-band hole-patterns for use as laser-frequency references. We measure frequency shifts due to magnetic fields, side-features of neighboring spectral holes, and changing optical probe power. A precise calibration of a temperature insensitive point is also performed, where the temperature-induced frequency shift is canceled to first order by the pressure-induced shift from the crystal's helium-gas environment.