High Average Power Second-Harmonic Generation of a CW Erbium Fiber MOPA

Abstract

We report the generation of 28 W of 780 nm radiation with near diffraction limited beam quality (M 2 ≤1.15) by frequency-doubling a continuous-wave (CW) erbium fiber master oscillator power amplifier (MOPA) system in a periodically poled lithium niobate crystal. The second-harmonic generation conversion efficiency reached 45% with no rolloff observed, suggesting that further power scaling should be possible with higher fundamental pump powers. The generated second-harmonic had a 3 dB spectral bandwidth of 0.10 nm. The presented architecture represents a simple and effective route to generating high-brightness radiation around 780 nm.

Zn-indiffused diced ridge waveguides in MgO:PPLN generating 1 watt 780 nm SHG at 70% efficiency

“…To support large atom condensates, watt-level powers with linewidths below the hyper-fine atomic transition energies are desired [5]. Generating this laser output has been achieved using established narrow linewidth lasers and bulk periodically poled lithium niobate (PPLN) crystals [5][6][7], however these require >10 W pump sources limiting field-based applications in QT, such as portable gravity measurements. Nonlinear waveguide have been used to enable more efficient conversion of laser pump sources, with some commercial availability for <250 mW operation.…”

High efficiency frequency doubling with a passive enhancement cavity

“…Nowadays, the development of a high-power fiber laser is very rapid and comprehensive, especially in the near-IR wavelength range. Hence, frequency doubling of fiber lasers becomes one of the most prospective methods to generate high-power visible sources [6][7][8][9]. The common method is to use an external enhancement cavity to achieve high-efficiency and high-power frequency doubling, which utilizes both the advantage of the high-power output of fiber lasers and the cavity enhancement [10].…”