Generation of 130  mW of 3975  nm tunable laser via ring-cavity-enhanced frequency doubling

Abstract

We report on the frequency doubling of a tapered amplifier-boosted distributed-Bragg-reflector continuous-wave laser system at 795 nm, using a PPKTP crystal placed in an external ring cavity. A tunable 397.5 nm violet laser power of 130 mW with a mode-matched input 795 nm laser power of 416 mW is obtained (conversion efficiency η 31%), limited by thermally induced bistability. However, when the violet laser is at the maximum output, a stable operation more than 30 min is hard to reach due to thermal effects. With a scanning cavity, the peak violet laser power rises up to 180 mW, corresponding to an overall efficiency of η 43%. The generated 397.5 nm laser with good beam quality and satisfying power has huge potential use in quantum optics and cold-atom physics.

Comparative study of the frequency-doubling performance on ring and linear cavity at short wavelength region

“…External cavity frequency doubling is an effective method of generating the violet wavelength laser source [9][10][11][12]. However, the wavelength of 397.5 nm is at the cut-off wavelength of many non-linear optical crystals (i.e the most popular crystal, periodically poled potassium titanyle phosphate PPKTP) along with high absorption coefficient, which induces severe thermal effect and grey tracking, when it is used for second-harmonic generator (SHG) at higher power density level [9,13].…”

Improvement of vacuum squeezing resonant on the rubidium D1 line at 795 nm

“…This is due to the thermally induced bistability, which is caused by the absorption of the UV beam inside the crystal. As we discussed in our previous papers [32,33], this thermally induced bistability prevents locking of the cavity to the top of the distorted fringe, leading to the decline of the doubling efficiency. In order to keep a stable locking of the cavity, we restrict the maximum fundamental power to 240 mW, corresponding to a UV output of 137 mW.…”

Development and characterization of a 22 W narrow-linewidth 3186 nm ultraviolet laser

“…This condition results in an optimized waist of 20.9 μm in our case. However, as the power of the 637.2 nm laser reach 4 W, the circulating power in the cavity reaches nearly 200 W. To circumvent thermal effects and possible damage to the crystal, we modestly ease the confocal focusing in the BBO crystal [22]. By numerical simulation, a set of newly optimized cavity parameters gives a total length of 616 mm, with 116 mm between M3 and M4.…”