R. Butkus

Trends in chirped pulse optical parametric amplification

Since the proof-of-principle demonstration of optical parametric amplifier to efficiently amplify chirped pulses in 1992, optical parametric chirped pulse amplification (OPCPA) became a widely recognized and rapidly developing technique for high-power femtosecond pulse generation. In the meantime, we are witnessing an exciting progress in the development of powerful and ultrashort pulse laser systems that employ chirped pulse parametric amplifiers. These systems cover a broad class of femtosecond lasers, with output power ranging from a few gigawatts to hundreds of terawatts, with a potential of generating few-optical-cycle pulses at the petawatt power level. In this paper, we discuss the main issues of optical parametric chirped pulse amplification and overview recent progress in the field.

Multimillijoule chirped parametric amplification of few-cycle pulses

The concept of optical parametric chirped-pulse amplification is applied to attain pulses with energies up to 8 mJ and a bandwidth of more than 100 THz. Stretched broadband seed pulses from a Ti:sapphire oscillator are amplified in a multistage noncollinear type I phase-matched beta-barium borate parametric amplifier by use of an independent picosecond laser with lock-to-clock repetition rate synchronization. Partial compression of amplified pulses is demonstrated down to a 10-fs duration with a down-chirped pulse stretcher and a nearly lossless compressor comprising bulk material and positive-dispersion chirped mirrors.

Generation of carrier-envelope-phase-stable 2-cycle 740-μJ pulses at 2.1-μm carrier wavelength

We produce carrier-envelope-phase-stable 15.7-fs (2-cycle) 740-μJ pulses at the 2.1-μm carrier wavelength, from a three-stage optical parametric chirped-pulse amplifier system, pumped by an optically synchronized 49-ps 11-mJ Nd:YLF laser. A novel seed pulse spectral shaping method is used to ascertain the true amplified seed energy and the parametric superfluorescence levels.

Progress in chirped pulse optical parametric amplifiers

We discuss the main issues of optical parametric chirped pulse amplification and overview recent progress in the field. Although we distinguish between the two operating modes of modern chirped pulse parametric amplifiers, OPCPA and NOPA, we reveal that both represent the same technique and share a common concept.

Enhanced stimulated Raman scattering in optical parametric oscillators from periodically poled KTiOPO4

Enhanced Raman scattering and concurrent Raman oscillation have been observed in nanosecond optical parametric oscillators in the near-infrared spectral region for certain periodicities of periodic ...

Hole trapping time measurement in low-temperature-grown gallium arsenide

We study hole dynamics in GaAs layers grown by molecular-beam epitaxy at 270 °C by two-color pump-and-probe experiments employing femtosecond 800-nm-wavelength pulses for sample’s excitation and 9-μm-wavelength pulses for probing the induced intervalence band absorption. Hole trapping time in as-grown, undoped layer is equal to 2 ps; it increases after thermal annealing or Be doping, and decreases in Si-doped layer. The mechanism of the hole trapping is discussed; it is shown that experimental observations are consistent with the hole trapping at neutral arsenic antisites model.

High-efficiency parametric oscillation and spectral control in the red spectral region with periodically poled KTiOPO4

Narrow-linewidth optical pulses at wavelengths near 630 nm with 2.2-mJ energy were generated with 61% efficiency in a periodically poled KTiOPO(4) parametric oscillator pumped by a frequency-doubled Q -switched Nd:YAG laser. The tuning range was extended to 30 nm by a noncollinear elliptical pumping geometry. We demonstrate that by angular dispersion a noncollinear optical parametric oscillator can be used to control the spectral and spatial characteristics of the output signal beam.

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.

Nonlinear self-reconstruction of truncated Bessel beam

It is demonstrated that by blocking of the part of Bessel light beam azimuthal aperture, a far field ring is completely reconstructed in azimuth and partially in intensity after the beam passes through a benzene cell. The phenomenon is explained as beam self-action (degenerate four-wave mixing) in the medium with Kerr nonlinearity. A qualitative agreement of the theoretical predictions with experimental results is obtained.

Two and Three Beam Pumped Optical Parametric Amplifier of Chirped Pulses

We present two and three beam pumped optical parametric amplifier of broadband chirped pulses. The seed pulses from Ti:sapphire oscillator were stretched and amplified in a non‐collinear geometry pumping with up to three beams derived from independent laser amplifiers. The signal with ∼90 nm bandwidth was amplified up to 0.72 mJ. The conversion efficiency dependence on intersection angles of pump beams is also revealed.