John D. Hybl

High-energy, kHz-repetition-rate, ps cryogenic Yb:YAG chirped-pulse amplifier

We demonstrate amplification of picosecond laser pulses to 40?mJ at a 2?kHz pulse repetition frequency (PRF) from a two-stage cryogenic chirped-pulse Yb:YAG amplifier, composed of a regenerative amplifier (RGA) and a two-pass booster amplifier. The RGA produces 8.2mJ of energy at 2kHz PRF and 13.2mJ at 1kHz PRF with excellent energy stability (approximately 0.3% rms) and beam quality (M(2)<1.1). Pulse stretching and compression are achieved by using a chirped fiber Bragg grating and a multilayer dielectric grating pair, respectively. Compressed 15?ps pulses from the RGA are obtained with a throughput efficiency of approximately 80% (approximately 6.5 mJ for 2kHz). The booster amplifier further amplifies the pulses to 40mJ at 2kHz PRF, and approximately 32 mJ, approximately 15 ps pulses are expected after compression. The amplifier chain seeded from a femtosecond Yb-fiber laser enables the optical self-synchronization between signal and pump in optical parametric chirped-pulse amplifier applications.

Generation of 287 W, 5.5 ps pulses at 78 MHz repetition rate from a cryogenically cooled Yb:YAG amplifier seeded by a fiber chirped-pulse amplification system

We generate linearly polarized, 287 W average-power, 5.5 ps pulses using a cryogenically cooled Yb:YAG amplifier at a repetition rate of 78 MHz. An optical-to-optical efficiency of 41% is obtained at 700 W pump power. A 6 W, 0.4 nm bandwidth picosecond seed source at 1029 nm wavelength is constructed using a chirped-pulse fiber amplification chain based on chirped volume Bragg gratings. The combination of a fiber amplifier system and a cryogenically cooled Yb:YAG amplifier results in good spatial beam quality at large average power. Low nonlinear phase accumulation as small as 5.1 x 10(-3) rad in the bulk Yb:YAG amplifier supports power scalability to a > 10 kW level without being affected by self-phase modulation. This amplification system is well suited for pumping high-power high-repetition-rate optical parametric chirped-pulse amplifiers.

Laser-induced fluorescence-cued, laser-induced breakdown spectroscopy biological-agent detection

Methods for accurately characterizing aerosols are required for detecting biological warfare agents. Currently, fluorescence-based biological agent sensors provide adequate detection sensitivity but suffer from high false-alarm rates. Combining single-particle fluorescence analysis with laser-induced breakdown spectroscopy (LIBS) provides additional discrimination and potentially reduces false-alarm rates. A transportable UV laser-induced fluorescence-cued LIBS test bed has been developed and used to evaluate the utility of LIBS for biological-agent detection. Analysis of these data indicates that LIBS adds discrimination capability to fluorescence-based biological-agent detectors. However, the data also show that LIBS signatures of biological agent simulants are affected by washing. This may limit the specificity of LIBS and narrow the scope of its applicability in biological-agent detection.

100-W

This work describes a cryogenic, electro-optically <i>Q</i>-switched Yb:YAG laser that generates 114-W average TEM₀₀ power with 47% optical-to-optical efficiency. Pulse repetition frequency is 5 kHz, pulse duration is 16 ns full-width at half-maximum, and <i>M</i> ² is less than 1.05.

Q

A high-power, actively modelocked, cryogenically cooled Yb:YAG laser has been demonstrated. At a repetition rate of 80 MHz, 214-ps pulses with 55 W of output power have been measured.

-switched Cryogenically Cooled Yb:YAG Laser

A 2-kHz, 40-mJ picosecond laser system based on chirped-pulse amplification with cryogenic Yb:YAG is demonstrated. 6.5-mJ, ~15-ps pulses with ~0.3% rms energy-stability are obtained from a regenerative amplifier and amplified to 80-W average power.

High-Power, Actively Modelocked Cryogenic Yb:YAG Laser

The properties of solid-state laser materials at cryogenic temperature are attractive for high-power operation and efficiency. In recent experiments, the power scalability and high efficiency have been demonstrated in simple laser architectures.

Generation of 2-kHz, 40-mJ Picosecond Pulses from a Cryogenic Yb:YAG Chirped-Pulse Amplifier for OPCPA Pumping

We generate linearly polarized, 287-W average-power, 5.5-ps pulses with 0.3-nm bandwidth at 1029 nm using a cryogenically-cooled Yb:YAG amplifier at 78 MHz for OPCPA applications.