Optimization of line-focusing geometry for efficient nonlinear frequency conversion from copper-vapor lasers

Detailed parametric investigations of line foci for efficient nonlinear frequency conversion of copper-vapor lasers are presented. For a single medium-scale copper-vapor laser (nominally 20 W), the optimum focal geometry for efficient second-harmonic and sum-frequency generation in BBO is to focus a 3.75-mm-diameter beam into the crystal with an f=60 mm cylindrical lens, Using such a focal geometry, UV powers of up to 1.75 W (SHG of the green), 1.2 W (SHG yellow), and 1.5 W (SFG) have been produced with peak instantaneous conversion efficiency of up to 48%. Conversion efficiencies are most sensitive to the F-number of the cylindrical focusing, with the optimum F-number being approximately 16, and are relatively insensitive to the width of the focused beam.

[1]  D. Coutts,et al.  Progress in high-speed UV micro-machining with high repetition rate frequency-doubled copper vapour lasers , 1994 .

[2]  V. O. Troitskii,et al.  LASER SPECTRA, TUNING, AND STABILITY: Nonlinear frequency conversion of copper vapor laser radiation , 1987 .

[3]  W. R. Bosenberg,et al.  Laser-induced damage in beta-barium metaborate , 1988 .

[4]  D. Coutts,et al.  Nonlinear frequency conversion of CVL fundamental and second-harmonic outputs , 1993 .

[5]  M. D. Ainsworth,et al.  Enhanced efficiency of UV second harmonic and sum frequency generation from copper vapor lasers , 1990 .

[6]  G. Toci,et al.  Efficient second harmonic generation in beta-barium borate by a diffraction-limited copper vapor laser. , 1992, Applied Optics.

[7]  D. Coutts,et al.  One watt average power by second harmonic and sum frequency generation from a single medium scale copper vapor laser , 1992 .

[8]  A. Isaev,et al.  Second harmonic generation from pulsed copper vapor laser radiation , 1980 .

[9]  G. Naylor,et al.  Frequency doubling of a 100-W copper laser for high power UV generation , 1989 .

[10]  H. S. Vora,et al.  Large‐bore copper vapor laser with a double thyratron pulse modulator , 1993 .

[11]  W. Molander.  High-average-power second-harmonic generation using a copper laser oscillator/amplifier source , 1994 .

[12]  David W. Coutts,et al.  Time resolved beam divergence from a copper vapor laser with unstable resonator , 1995 .

[13]  M. D. Ainsworth,et al.  Efficient green/yellow conversion of copper vapour laser output , 1990 .

[14]  M. Norton,et al.  Improved efficiency of second-harmonic generation in BBO using the 511-nm line of an injection-seeded copper laser , 1991 .