Alex Dergachev

Review of Multipass Slab Laser Systems

The multipass slab (MPS) solid-state laser design is a diode-laser, side-pumped configuration that combines high efficiency with high beam quality. Because of a relatively low volumetric thermal loading, the MPS configuration can be used with a wide variety of laser crystals to operate at relatively high powers, and in this paper, we review the MPS lasers based on the materials Nd:YLF, Nd:YVO, Tm:YLF, Er:YLF, Yb:S-FAP, and Cr:LiSAF.

High-energy, kHz-rate, picosecond, 2-μm laser pump source for mid-IR nonlinear optical devices

To the best of our knowledge this is the first demonstration of a 2-μm, Ho:YLF laser source based on a mode-locked oscillator/regenerative amplifier combination and a subsequent single-pass amplifier stage to produce picosecond pulse trains at 1-10 kHz rate with up to ~11 mJ of pulse energy. Further pulse energy scaling can be achieved through addition of single-pass amplifier(s). Availability of 2-μm, kHz-rate lasers providing 10-100-mJ, picosecond-scale pulses is critical for the development of short-pulse mid-IR nonlinear optical devices, in general, and for construction of femtosecond OPCPAs for high-harmonic generation and terahertz generation, in particular.

Efficient room temperature LiF :F2+** color center laser tunable in 820-1210 nm range

Abstract Efficient room temperature operation of a LiF:F 2 +** color center laser at record levels of output energy (up to ∼100 mJ) and average power (up to ∼1.4 W) with a very wide 796–1210 nm tuning range is described. A photo- and thermostable lasing was realized due to: (i) improved technology of LiF crystals with stabilized F 2 +** color centers and (ii) appropriate choice of the pumping laser wavelength. Record real efficiencies for LiF:F 2 +** laser, 28% under pumping by radiation of an alexandrite laser (740 nm) and 53% under pumping by Raman shifted (H 2 and D 2 ) second harmonic of a Nd:YAG laser (683 and 633 nm), were achieved.

Effects of Pulse Rate and Temperature on Nonlinear Absorption of Pulsed 262-nm Laser Light in β-BaB2O4

The efficiency of multi-watt ultraviolet radiation generation by harmonics processes in β-BaB2O4 (BBO) can be improved by reducing thermal dephasing. The dephasing arises from local heating of BBO by the linear absorption of green (second harmonic) and ultraviolet (fourth harmonic) radiation by crystal defects that are induced by two-photon absorption of high peak power ultraviolet radiation. Such absorption can be reduced by decreasing the repetition rate to ~1 kHz to allow the defects to decay between the laser pulses and/or heating BBO crystal to 150–200 °C to increase the decay rate of the induced defects.

High-power, high-energy Ho:YLF laser pumped with Tm:fiber laser

We report an efficient, TEM00, Tm:fiber-laser-pumped, Ho:YLF laser producing 43 W cw power and 45 mJ of pulse energy in the Q-switched regime, the highest values yet reported for this material.

A CW side-pumped Tm:YLF laser

We report on a broadly tunable (1905 - 2067 nm) diode-pumped Tm: YLF laser producing cw output powers of >18 W (37% slope efficiency) in multimode operation and 12 W in the TEM00 mode.

Short-pulse, high-repetition rate, high-power Nd:YLF MOPA system

We report a diode-pumped, Nd:YLF, Q-switched, short-pulse, 30-100-kHz MOPA system producing, to our knowledge, the highest third- and fourth-harmonic powers (25 and 10 W, respectively) yet reported for high-pulse-rate Nd-doped lasers.

High-Power, High-Energy Diode-Pumped Tm:YLF-Ho:YLF-ZGP Laser System

We report an efficient, TEM00, Tm:YLF-pumped Ho:YLF laser system producing 21 W CW power and 37 mJ of pulse energy in the Q-switched regime, the highest values yet reported for this material. A ZGP OPO pumped by the Ho:YLF laser produced pulse energies above 10 mJ at 50-400 Hz.

Powerful, room-temperature stable LiF:F2+** tunable laser

A powerful photo- and thermostable, LiF:F2+ color center laser pumped by radiation at 740 nm or at 683 nm is described. This is the first time an average power as high as approximately 1.4 W and an energy per pulse as high as approximately 100 mJ, with record real efficiency of 53 percent and 28 percent were achieved for a room temperature LiF:F2+ color center laser. Such color center laser, tunable in the 820-1210 nm range, features a number of important advantages over pulsed lasers based on Ti or Cr doped crystals.

Efficient Third-Harmonic Generation with a Ti:sapphire Laser

We report the highest efficiency (to the best of our knowledge) third-harmonic generation from a gain-switched Ti:sapphire laser. Using Type I LBO crystals, we obtained ~45 % conversion in the sum-frequency stage and ~35% overall conversion from the fundamental. The diode-laser-injection-seeded Ti:sapphire laser operated in 920-960 nm range to provide 307-320-nm UV energy.