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Efficient Raman frequency conversion of high‐power fiber lasers in diamond
Author(s) -
Williams Robert J.,
Nold Johannes,
Strecker Maximilian,
Kitzler Ondrej,
McKay Aaron,
Schreiber Thomas,
Mildren Richard P.
Publication year - 2015
Publication title -
laser and photonics reviews
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.778
H-Index - 116
eISSN - 1863-8899
pISSN - 1863-8880
DOI - 10.1002/lpor.201500032
Subject(s) - materials science , raman spectroscopy , energy conversion efficiency , laser , raman scattering , raman laser , optics , diamond , optoelectronics , laser beam quality , fiber laser , brillouin scattering , synthetic diamond , laser power scaling , chemical vapor deposition , laser beams , physics , composite material
We report high‐power frequency conversion of a Yb‐doped fiber laser using a double‐pass pumped external‐cavity diamond Raman oscillator. Pumping with circular polarization is shown to be efficient while facilitating high‐power optical isolation between the pump and Raman laser. We achieved continuous‐wave average power of 154 W with a conversion efficiency of 50.5% limited by backward‐amplified light in the fiber laser. In order to prove further scalability, we achieved a maximum steady‐state Raman‐shifted output of 381 W with 61% conversion efficiency and excellent beam quality using 10 ms pump pulses, approximately a thousand times longer than the transient thermal time‐constant. No power saturation or degradation in beam quality is observed. The results challenge the present understanding of heat deposition in Raman crystals and foreshadow prospects for reduced thermal effects in diamond than originally anticipated. We also report the first experimental evidence for stimulated Brillouin scattering in diamond.