Northrop Grumman Corporation has made significant progress in the development of compact, high power, continuous
operation solid state lasers for military applications during the past six years. The Joint High Power Solid State Laser
(JHPSSL) program is nearing completion of its third phase; its key objective is to demonstrate a 100kW solid state laser
with excellent beam quality. Northrop's unique scalable architecture coherently combines modular 15kW lasers to
produce power levels of 100kW and beyond with excellent beam quality and run times. This paper describes the
JHPSSL program history, Northrop's high power solid state laser architecture and our demonstrated results.
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.
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.
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.