Generation of 656 nm coherent red-light by frequency-doubled Nd:YLiF4/β-BaB2O4 laser for a compact silver atoms optical clock

Abstract

We describe an efficient continuous-wave diode-pumped Nd:YLiF4 laser oscillating on the σ-polarized 4F3/2-4I13/2 transition at λω = 1312 nm. With a simple linear cavity laser, we reached an intracavity power of 310 W at λ = 1312 nm for 16 W of absorbed pump power (λp ~ 806 nm). A 0.25 W of tunable radiation (λ2ω = 656−658 nm) was obtained by intracavity second-harmonic generation (SHG) with a 5 × 5 × 7 mm3β-BaB2O4 crystal. Up to 10 mW of tunable single-frequency operation was observed using a 200 μm thin fused silica intracavity solid etalon. The optimal waist for a maximum conversion efficiency has been calculated theoretically using Boyd and Kleiman model. For the 1312–656 nm SHG, we found a walk-off parameter B = 8.99 and an optimal waist of 25 μm. Comparing to the experimental measurement of the optimal waist, we found a relative discrepancy of 2.84 × 10-2. This laser is dedicated to the spectroscopic study of silver atoms trapped in a buffer-gas-free paraffin coated Pyrex cell that will be used in a compact atomic optical clock.