Singly resonant optical parametric oscillator in periodically poled KTiOPO(4) pumped by a Bessel beam.

Conical pumping was used in a periodically poled KTiOPO(4) optical parametric oscillator for singly resonant idler generation in a nearly diffraction-limited axial beam. A single signal-idler pair was generated over the whole tuning range by use of asymmetric reflectivity of the OPO mirrors. Pump depletion of 40% and total conversion efficiency of 27% were obtained. Additional OPO tuning capability was demonstrated by adjustment of the angle of the conical pump beam.

Diode-Pumped Er-Yb:Glass Laser Passively Q Switched by Use of Co(2+):MgAl(2)O(4) as a Saturable Absorber.

We report on passively Q-switched operation of a diode-pumped Er-Yb:glass laser with a Co(2+):MgAl(2)O(4) plate as a saturable absorber. Optical pulses with peak power exceeding 2 kW and a pulse length of 2.3 ns have been generated. Single-longitudinal-mode Q-switched operation at 1.53 mum has been obtained by use of the Co(2+):MgAl(2)O(4) plate as an intracavity etalon. A discussion of the optimal Er(3+) concentration as well as optimization of the cavity design is included.

Efficient Nd:YAG Laser Frequency Doubling with Periodically Poled KTP.

Periodically poled flux-grown KTiOPO(4) was used for efficient extracavity 1064-nm Nd:YAG laser frequency doubling. A conversion efficiency exceeding 65% was obtained in Q-switched operation, and 1.34 W of average frequency-doubled power was generated with 2.2 W of mode-locked laser output. The conversion efficiency is approximately two times higher for periodically poled KTP than for conventional type II phase-matched KTP. The measurements indicate that periodically poled KTP is less susceptible to optical damage than type II KTP.

Design of fiber gratings for total dispersion compensation.

An optical fiber grating has theoretically been designed that would be capable of compressing a dispersionbroadened pulse of 100 ps down to the transform limit of 20 ps, with a total reflectance of ~75%. A numerical recipe is presented for the design of a fiber grating, whose spectral response closely follows an arbitrarily chosen profile, both for the reflectance and the phase factor. The resulting grating consists of a number of subgratings, all of which have the same grating period but a different spatial phase and coupling coefficient.

Hybrid diode-laser fiber-amplifier source of high-energy ultrashort pulses.

We demonstrate what we believe is the first compact laser system for generating ultrashort microjoule-energy optical pulses. Linearly chirped pulses from monolithic tunable Bragg-reflection laser diodes were amplified in a diode-pumped two-stage erbium-doped fiber amplifier and compressed with a grating-pair compressor. The laser diodes had their emission wavelengths at 1.538 and 1.562 microm. The highest pulse energies obtained were 2 microJ at the repetition frequencies of 1-10 kHz and were at the saturation energy level of the fiber amplifier. The shortest duration of compressed pulses is 1.8 ps.