Larry R. Marshall

Highly efficient TEM00 operation of transversely diode-pumped Nd:YAG lasers.

Improved pumping geometries and tailored cavity modes result in a 32% optical-to-optical slope efficiency for TEM00 output from a transversely diode-pumped Nd:YAG laser. Energies of 60 mJ are obtained for multimode operation and 50 mJ for single-mode operation, which represent an 80% extraction of the multimode energy as TEM00 output. The electrical slope efficiency for TEM00 operation is 17%.

Efficient optical parametric oscillator at 1.6 μm

We extend the operating regime of diode-pumped Nd:YAG lasers into the eye-safe region at 1.61 microm by using an efficient optical parametric oscillator in KTP. Total energy conversion efficiencies of the 1.06-microm pump to 1.61-microm signal and 3.1-microm idler approach 40%, with 25% converson to 1.61microm alone. This device has a wallplug efficiency of 0.8%, producing 2.5-mJ output energies at an eye-safe wavelength, and is readily scalable to higher energies.

Intracavity doubled mode-locked and CW diode-pumped lasers

A CW-diode-pumped Nd:YAG laser producing 12.5 W of multimode output at 1.064 mu m is described. Mode locking and intracavity doubling produced 3 W of output at 0.532 mu m with an amplitude stability better than +or-1% rms. Up to 2.8 W at 0.532 mu m was obtained when the laser was run CW without mode locking. Stabilities equal to those obtained from the mode-locked laser were observed from the CW laser by axially rotating either the laser rod or KTP doubling crystal into a fixed relative orientation. >

Diode-pumped eye-safe laser source exceeding 1% efficiency

We describe an all-solid-state, diode-pumped, eye-safe laser source at 1.61 microm, based on a Nd:YAG laser and a noncritically phase-matched KTP optical parametric oscillator. Total energy conversion efficiencies of the 1.064-microm pump to 1.61-microm signal and 3.1-microm idler approach 50%, with 35% conversion to 1.61 microm alone. This device produces 1.6 mJ at 1.61 microm with a wallplug efficiency of 1.1% and is readily scalable to higher energies. Tunability over 1.6 to 1.54 microm is obtained by rotation of the KTP crystal about its z axis, with 1.54-microm output obtained for propagation along the y axis under noncritical phase matching.

Highly efficient optical parametric oscillators

An eyesafe source (1.61 micrometers ) with 1.1% wallplug efficiency, is demonstrated using a Nd:YAG pumped KTP optical parametric oscillator with peak-power conversion efficiencies of 70%. Joule-level scaling, kHz repetition-rates, and ns pulselengths are now accessible using this technology.

3-W continuous-wave diode-pumped 532-nm laser

A cw diode-pumped Nd:YAG laser is mode locked at 80 MHz and produces 5.5 W of output at 1.064 microm. Intracavity frequency doubling by using KTP produces 3 W of mode-locked output at 0.532 microm.

Multimode pumping of optical parametric oscillators

Calculations suggest that optical parametric oscillators (OPOs) can be efficiently pumped using multimode, divergent pump sources. The influence of pump beam divergence and mode structure upon OPO performance is measured for both noncritical phase-matching, and OPOs with walkoff. Multimode OPO pumping is shown to be efficient, provided appropriate nonlinear crystals and OPO cavities are employed; the nonlinear crystal must have sufficient angular acceptance to tolerate a divergent pump; the OPO cavity must support modes that match the divergence and spatial intensity characteristics of the pump, For low-order pump modes, the OPO can be made to match the mode of the pump. Higher order pump modes reduce the OPO efficiency, and cause a saturation of efficiency with increasing pump power. The efficiency is degraded in a similar fashion in the presence of walkoff. Multimode pumping is more difficult in longer OPO cavities due to increased buildup time of higher order OPO modes.

Continuously tunable diode-pumped UV-blue laser source.

Continuous tunability and high efficiency are obtained from an intracavity-doubled optical parametric oscillator pumped by a frequency-doubled diode-pumped Nd:YAG laser. The optical parametric oscillator is tunable from 760 to 1040 nm with 30% efficiency, giving 380-520-nm tunability after intracavity doubling with 40% efficiency.

Laser-diode-pumped transient mode locking

The authors have developed a pulsed diode-pumped mode-locked Q-switched and cavity-dumped Nd:YAG oscillator. Transient mode locking is discussed, with emphasis on the advantages of laser diode arrays as the pump source. Pulsed two-dimensional laser diode arrays are used to side pump the oscillator producing a single output pulse at 20 Hz with a pulse length of 95 ps and energy of 1 mJ. >

Transient stimulated Raman scattering in lead vapor

An investigation of stimulated Raman scattering (SRS) of short-pulse (6-ns) XeCl-laser radiation in Pb vapor is reported. Conversion efficiencies, based on peak power, up to 15% have been obtained for Pb-oven temperatures of 1260 degrees C. The functional dependence of conversion efficiency, in the short-pulse regime, upon buffer-gas pressure and species differs significantly from that observed for long-pulse (>20-ns) pumping, corresponding to steady state behavior. Analysis of the data and comparison with transient SRS in H/sub 2/ yield an estimate of T/sub 2/ approximately=1ns for the transient response time T/sub 2/ of Pb vapor. The observed pressure effects are explained in terms of a reduction in T/sub 2/, and hence Raman gain, by collisions with buffer-gas atoms. >