Laser bulk damage thresholds were measured for both single-crystal YAG and for diffusion-bonded YAG structures
using 600 picosecond pulses at 1064 nm. The tested samples included 3-layer sandwich structures with doped cores
of various thicknesses. An undoped-YAG end cap was diffusion-bonded on one end of each of the sandwiches. The
1064 nm laser source was focused to a 13 micron diameter spot at the boundary region between the core and the
undoped endcap. Measurements included the evaluation of single- and multiple-pulse damage thresholds at single
sites, as well as thresholds for continuous 90%-overlap scans. The single-site thresholds at the diffusion-bonded
boundary were close to that of single-crystal YAG. However, the continuous scans revealed isolated microscopic
sites where the damage threshold was as much as 4 times lower than that of single-crystal YAG.
We demonstrate passively Q switched 2% doped Er:YAG laser operation in the eyesafe region with sub 5 nsec pulse widths using Cr<sup>2+</sup>:ZnSe as a saturable absorber. A rod geometry operating in the burst mode and a micro slab geometry operating continuously are described. The micro slab geometry generates 6nsec passively Q switched pulses with over 1.5 Watt of output power and with multi kilohertz pulse repetition rates. The lasers are resonantly pumped with a 1534nm fiber laser.
In this paper, we report a diode-pumped passively Q-switched Yb:YAG laser that is an excellent candidate for a ladar master oscillator. This microchip laser has 1 ns pulse duration, 68 μJ pulse energy, 700 mW average power, 10 kHz repetition rate, and 29% optical slope efficiency. Additionally, the microchip oscillates in the fundamental TEM<sub>00</sub> mode. The peak power was measured as high as 66 kW. We compare the pulse shape and duration, and the beam quality to simulation. We study the effects of Q-switch absorption, output coupler reflectivity, cavity length, and pump power on the laser's pulse duration, pulse energy, average power, and repetition rate.
New solid-state passive Q-switch materials for the Er:glass laser at 1.53 micrometers are described. Saturable absorber Q-switching has been obtained using U<SUP>4+</SUP>:SrF<SUB>2</SUB>, Er<SUP>3+</SUP>:CaF<SUB>2</SUB>, and Er<SUP>3+</SUP>:Ca<SUB>5</SUB>(PO<SUB>4</SUB>)<SUB>3</SUB>F.
We report on new eyesafe laser hardware developed at Hughes Aircraft Company. We also report on the development of a compact 20 Hz pulse repetition frequency (PRF) backward Raman configuration and the investigation of deuterium as an alternative to methane for high PRF eyesafe Raman lasers.
Laser rangefinders operating at 1. 54 jtm are of increasing interest because of their eyesafe property. We report on technology and hardware developed at Hughes Aircraft Company based on using Stimulated Raman Scattering (SRS) of the Nd:YAG 1. 06 im output to the eyesafe 1. 54 jtm wavelength. This technology has been extended from the 1 Hz repetition rate to the 10 to 20 Hz range for air defense applications by use of circulating gas Raman cells and several resonator configurations have been developed to improve conversion efficiency and beam divergence. The eye safety and the atmospheric penetration of the 1. 54 jim wavelength is discussed.