Characterization of Single-Frequency Yb:$ \hbox{KYF}_{4}$ Lasers at 1.03 $\mu\hbox{m}$ for Optical Frequency Metrology

Abstract

A longitudinally pumped, widely tunable, solid-state Yb:KYF4 laser was developed with special design for applications to optical frequency metrology and absolute frequency stabilization. The KYF4 crystalline host, combined with efficient diode pumping, allows for wide wavelength tunability at about 1.03 mum in a single transverse mode. Two different laser cavity designs were experimentally investigated. The combined use of an intracavity birefringent filter and uncoated glass etalons provides single-frequency output power at the 100-mW level in a folded-cavity resonator. A second hemispherical linear cavity was also developed with one or two coated intracavity etalons for single-frequency operation. The novel laser sources were thoroughly characterized in terms of output power and beam quality, amplitude noise, wavelength tunability, and single-axial-mode operation. High-quality TEM00 single-frequency laser radiation opens the way to the development of a new optical frequency standard based on the I 2 molecule at 0.5- mum wavelength.