Carolyn S. Hoefer

High Power Conversion to Mid-IR Using KTP and ZGP OPOs

A high average power, OPO based system has been developed for the purpose of generating output in the 2 - 5 µm mid-IR band. The system uses a cw diode array - pumped, Nd:YAG master oscillator power amplifier (MOPA) as the pump source and two tandem OPOs for wavelength conversion to the mid-IR. A Type II degenerate KTP OPO was used to convert the pump beam to 2.13 µm and a Type I near degenerate zinc germanium phosphite (ZGP) OPO was used to generate broadband radiation in the 3.7 - 4.1 and 4.4 - 4.8 µm wavelength range.

One Joule Per Pulse, 100 Watt, Diode-Pumped, Near Diffraction Limited, Phase Conjugated, Nd:YAG Master Oscillator Power Amplifier

We have assembled and tested a diode-pumped, phase conjugated Nd:YAG master oscillator power amplifier (PC MOPA) operating at an average power of 100 Watts. 1 J per pulse has been extracted at a repetition rate of 100 Hz with a beam quality (BQ) of 1.1 x diffraction limited (D.L.). This combination of average power and beam quality makes this the brightest short pulse solid-state laser reported to date. The optical efficiency of 22% and the overall efficiency of 9.4% also represent record performance for high energy short pulse lasers. Excellent spatial uniformity and a pulse length of 7 ns make this laser ideal for frequency doubling and parametric conversion.

One joule per pulse, 100-W diode-pumped, near-diffraction-limited, phase-conjugated Nd:YAG master oscillator power amplifier

We have assembled and tested a diode-pumped, phase conjugated Nd:YAG master oscillator power amplifier (PC MOPA) operating at an average power of 100 Watts. One joule per pulse has been extracted at a repetition rate of 100 Hz with a beam quality (BQ) of 1.1 x diffraction limited (D.L.). This combination of average power and beam quality makes this the brightest short pulse solid-state laser reported to date. The optical efficiency of 22% and the overall efficiency of 9.4% also represent record performance for high energy short pulse lasers. Excellent spatial uniformity and a pulse length of 7 ns make this laser ideal for frequency doubling and parametric conversion.

High pulse-repetition-frequency mid-infrared optical parametric oscillators

Summary form only given. We present recent experimental results on average power scaling in periodically poled LiNbO/sub 3/ optical parametric oscillators (OPOs) and describes some of our observations on thermal loading effects. A cw diode-pumped, zigzag slab Nd:YAG oscillator provided pump radiation at a pulse length of 350 ns.

High average power frequency doubling

High average power second harmonic generation in crystals with finite absorption at the fundamental or harmonic wavelength creates unique problems. In addition to generating significant OPD which degrades the beam quality, heating of the crystal creates conditions which can be inherently temporally unstable. As the crystal is tuned towards phase matching, rapid changes in temperature cause the crystal to drift away from phase matching conditions which is followed by reduced frequency conversion. Experiments are in progress with three crystals, KTP, KD*P and KNbO/sub 3/, which have vastly different characteristics, to assess their potential for high average power doubling.<<ETX>>