Jacqueline G. Berg

Diode array pumped kilowatt laser

The diode array pumped kilowatt laser (DAPKL) has demonstrated more than an order of magnitude increase in brightness and average power for short pulse diode-pumped solid-state lasers since its inception in 1991. Significant advances in component technology have been demonstrated, including: development of a diffusion bonding process for producing large slabs of Nd:YAG laser material. Phase conjugation by stimulated Brillouin scattering (SBS) has been demonstrated with high reflectivity and fidelity in a simple focused geometry with input powers of 100 W. Pulse energies at 1.06 /spl mu/m of 10 J have been demonstrated with a beam quality of 1.5 times diffraction limited at the 500-W level. An average power of 875 W at 100 Hz has been obtained. Efficient frequency doubling with a record power of 165 W has been demonstrated with 5 J per pulse at 0.53 /spl mu/m. Work is ongoing to enclose the system in a compact brassboard with improved performance and long term stability.

Active tracker laser (ATLAS)

A high brightness diode-pumped, Nd-YAG solid state laser has been designed, fabricated, and tested. This phase conjugated master oscillator/power amplifier (MOPA) device produces 20-ns Q-switched pulses at 2500 Hz at an average power of 690 W and a beam quality of 1.1/spl times/DL when the pump diodes are operated at 27.5% duty cycle. With an external KTP doubler, this device has produced 175 W of green average power at a beam quality of 1.5 /spl times/ DL and a conversion efficiency of 45% over continuous operating times as long as one hour. This 1.06 /spl mu/m result is believed to be the highest average power brightness achieved, and the 532-nm performance is both the highest average green power and the highest average brightness ever reported.

Active Tracker Laser (ATLAS)

A phase conjugated Nd:YAG amplifier has demonstrated 690 W average power and 1.1 ×DL beam quality. The frequency doubled output was 175 W at 1.5 ×DL and 45% conversion efficiency. This is the highest average green power and highest average brightness reported.

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.

Diode-array-pumped kilowatt laser

The Diode Array Pumped Kilowatt Laser (DAPKL) has demonstrated more than an order of magnitude increase in brightness and average power for short pulse diode-pumped solid-state lasers since its inception in 1991. Significant advances in component technology has been demonstrated, including development of a diffusion bonding process for producing large slabs of Nd:YAG laser material. Phase conjugation by stimulated Brillouin scattering has been demonstrated with high reflectivity and fidelity in a simple focused geometry with input powers of 100 W. Pulse energies at 1.06 μm of up to 10 J per pulse have been demonstrated with a beam quality of 1.25 times diffraction limited at 33 Hz. An average power of 940 Watts at 100 Hz has been obtained with two times diffraction limited beam quality. Efficient frequency doubling with an average power of 165 W has been demonstrated with 5 J per pulse at 0.53 μm. The system has been packaged in a compact brassboard for long term stability and reliability of operation.

Modeling high-brightness kW solid state lasers

Several kW-class solid-state lasers at TRW are described with an emphasis on the performance modeling used to aid development of high brightness operation. Comparisons of results and analysis are presented for key aspects of high power, diode pumped, Nd:YAG lasers and amplifiers that use zigzag slab configurations to minimize thermal effects. Devices described include multi-kW power oscillators suitable for high power machining, welding, and material processing; and phase conjugated master oscillator/power amplifiers (MOPAs) which provide short pulse, high brightness beams for active tracking, photolithography, or remote sensing. Laboratory measurements are in good agreement with predictions of diode pump profile and absorption efficiency; slab extraction efficiency and thermal load; and slab OPD.

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>>