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We demonstrate the use of a nonlinear photonic crystal to generate a harmonic comb and an ultrabroad-band acousto-optic modulator for the field amplitudes and phases of the comb to succeed in synthesizing femtosecond and subfemtosecond optical field waveforms. Nonsinusoidal fields of various shapes are synthesized and verified using shaper-assisted linear cross-correlation. The compact all-solid-state system could lead to the realization of a portable arbitrary optical waveform synthesizer that is analogous in many aspects to an RF function generator.

We report a design for upconversion 435 nm blue lasers based on simultaneously fulfilling the nonlinear processes of optical parametric oscillation (OPO) and second-harmonic generation (SHG) in a 7.9 mum periodically poled lithium tantalate (PPLT). The uncoated 15-mm-long PPLT device exhibits a low threshold of 150 mW and a differential slope efficiency of 22.6%, rendering 56 mW blue generation when pumped by a pulsed 532 nm green laser with an average power rating of 400 mW. These observations were attributed to a quasi-phase-matching (QPM) structural design with a 75% domain duty cycle to ensure the concurrence of frequency doubling with the first-order QPM-OPO PPLT device via the second-order QPM-SHG process.

We report the generation of the second to the sixth harmonics of a fundamental frequency covering two and a half octaves in a multiply-periodically poled lithium tantalate crystal by cascaded quasi-phase-matched frequency mixing. A frequency comb that is composed of these harmonics will permit the synthesis of a train of periodic subcycle subfemtosecond pulses in a compact setting.

A model to analyze the interaction of the parametric fields being generated in a two-dimensional nonlinear photonic crystal has been developed. The analysis provides details of the interference of the generated wave(s) both inside and in the region just outside the crystal. The results are verified by second-harmonic generation in a LiNbO3 crystal that has been poled with a tetragonal inverted domain structure.

A high-power 532 nm-pumped multikilohertz nanosecond optical parametric oscillator using a periodically poled 1.0 mol.% MgO-doped stoichiometric lithium tantalate crystal that could be operated from room temperature to 200 degrees C without damage is reported. A broad continuous tuning range from 855 to 1410 nm was achieved within a single domain period. Efficient operation of high peak power and watt level average power with a power conversion of 62.5% was measured. These results show that a high-resolution high average power visible tunable source can be realized.

We demonstrate a tunable deep-ultraviolet coherent source generated by the beating of a tunable UV laser and strongly driven vibrational Raman coherence in hydrogen. The total energy conversion efficiency reaches a maximum of 50% at the phase side of the Raman coherence. The generated spectrum of Raman sidebands tunes with the input and extends from 435 to 146 nm for an input at 282 nm.

A compact, efficient optical parametric oscillator (OPO) for the visible to near-infrared region based on periodically poled stoichiometric lithium tantalate pumped by a frequency-doubled multikilohertz Q-switched Nd:YAG laser is demonstrated. Up to 61% photon conversion with a 71% slope efficiency for photon conversion from 532 nm to the signal radiation was measured. We observed that the efficient conversion diminished the potential for photorefractive damage induced by the 532 nm radiation in the crystal and made sustained operation of the OPO device possible.

With a laser-excited acoustic wave as the carrier wave and by modulation of the light wavelength of a multikilohertz-repetition-rate optical parametric oscillator at a lower frequency than the acoustic frequency, we demonstrate a wavelength-amplitude double-modulation technique and achieve an enhancement factor of 35 in sensitivity in photoacoustic trace gas detection with the technique.

A simple ring cavity consisting of mirrors reflecting at the second harmonic is used to generate the fourth harmonic of low-power Q-switched Nd:YAG laser pulses. A large beam waist of 1 mm minimized the effects of double refraction and thermal loading of the nonlinear crystals. By simulating the low-power pulses with a small portion of the output from a 30-Hz flash-lamp-pumped Q-switched Nd:YAG laser, we obtained IR-UV energy conversion as great as 39.5% to yield 84-mW average power at 266 nm from 213 mW of single-mode 1064-nm radiation.

Backward stimulated Brillouin scattering was used to control the growth of amplified spontaneous emission (ASE), reducing the unwanted emission in a pulse-amplified cw Ti:sapphire laser system from 22% to less than 1 x 10(-4) in the final output. Suppression of ASE substantially improved the spectral quality of the laser and broadened the range over which the laser is useful. The output duration was compressed, but the pulse remained nearly transform limited.

Photon conversion efficiencies of 60% at 2.92 microm and 25% at 4.5 microm of a high-power injection-seeded Ti:sapphire laser have been achieved by difference frequency mixing with the new crystal KTiOAsO(4).

Third-harmonic generation to 1182 A is reported in a pulsed supersonic jet of xenon. Using a valve equipped with a 1-mm-diameter nozzle and for an incident power of 18 MW at 3547 A, I have obtained a peak power of 260 W in a 2.9-nsec pulse, corresponding to 4.7 x 10(11) photons per pulse and an average power of 7.5 microW at 1182 A. The measured conversion efficiency is comparable with that in a bulk-gas cell.