Audrius Zaukevicius

Femtosecond Yb:KGW MOPA driven broadband NOPA as a frontend for TW few-cycle pulse systems

White light continuum seeded noncollinear optical parametric amplifier driven by Yb:KGW master oscillator power amplifier (MOPA) system is reported. The demonstrated design provides amplification of broadband pulses at 800 nm up to 20 µJ energy at 1 kHz repetition rate and can be used as simple and reliable frontend source for systems producing high intensity few-cycle pulses. The amplified spectral bandwidth allows for <7 fs pulse durations and preliminary compression of partial spectrum yields sub-10 fs pulse.

Manifestation of spatial chirp in femtosecond noncollinear optical parametric chirped-pulse amplifier

In this paper the results of the theoretical and experimental study of spatiotemporal distortions emerging in noncollinear optical parametric chirped-pulse amplifiers are presented. In a noncollinear parametric amplifier, when the pulse fronts of the pump and signal are not matched, the signal pulse becomes tilted and, aside from angular dispersion, has a spatial chirp. The expressions relating the magnitudes of the acquired spatial chirp and angular dispersion to the temporal chirp of the signal pulse are derived. It is shown that the magnitudes of the induced spatial chirp and angular dispersion decrease at different rates with the increase of the signal pulse temporal chirp and, for the large temporal chirp, the spatial chirp mainly contributes to the pulse-front tilt of the signal, whereas the induced signal pulse tilt is independent of the signal pulse temporal chirp, but is always smaller than the tilt of the pump pulse.

Table top TW-class OPCPA system driven by tandem femtosecond Yb:KGW and picosecond Nd:YAG lasers

We present a compact TW-class OPCPA system operating at 800 nm. Broadband seed pulses are generated and pre-amplified to 25 μJ in a white light continuum seeded femtosecond NOPA. Amplification of the seed pulses to 35 mJ at a repetition rate of 10 Hz and compression to 9 fs is demonstrated.

Femtosecond wavelength-tunable OPCPA system based on picosecond fiber laser seed and picosecond DPSS laser pump.

We present a compact and stable femtosecond wavelength-tunable optical parametric chirped pulse amplification (OPCPA) system. A novel OPCPA front-end was constructed using a multi-channel picosecond all-in-fiber source for seeding DPSS pump laser and white light supercontinuum generation. Broadband chirped pulses were parametrically amplified up to 1 mJ energy and compressed to less than 40 fs duration. Pulse wavelength tunability in the range from 680 nm to 930 nm was experimentally demonstrated.

FORMATION OF FLAT-TOP PICOSECOND PUMP PULSES FOR OPCPA SYSTEMS BY CASCADE SECOND HARMONIC GENERATION

We report on the method for picosecond pulse envelope shaping that is based on pulse temporal profile transformations during the cascade second harmonic generation. It was demonstrated theoretically and experimentally that under a particular second harmonic generation condition, e. g. pump pulse intensity and crystal length, the 1064 nm pump pulses with a temporal profile close to the Gaussian one and pulse width of 75 ps at FWHM can be converted to pulses of fundamental and second harmonics with the super-Gaussian temporal profile having an intensity plateau region extending over a ~100 ps time interval when conversion efficiency in the first stage of the harmonic generator was around 45–50%. Our proposed shaping method is particularly suitable for the application in the multistage OPCPA pumped by the second harmonic of Nd:YAG laser radiation.

Novel OPCPA based source for broadband high resolution sum frequency generation spectroscopy

Sum frequency generation (SFG) spectroscopy is a powerful technique for characterization of vibrational bonds of molecules at surfaces and interfaces [1]. The principle of SFG is based on resonant nonlinear mixing of two optical pulses — typically one in MIR range and another visible (VIS). There are two main SFG spectroscopy techniques. Narrowband SFG (NB-SFG) is based on picosecond MIR and picosecond VIS source. Full spectral information is obtained by tuning MIR pulses through vibrational lines of the molecules. The typical resolution in NB-SFG is a few cm−1 [2]. In broadband SFG (BB-SFG) femtosecond MIR pulses with spectrum spanning a few hundred cm−1 are used. This allows for simultaneous recording of complete SFG spectra and reduces systematic errors due to sample degradation during the measurement. However in most experimental BB-SFG setups the same femtosecond laser source is used to produce narrowband VIS pulses. Therefore typical resolution obtained with BB-SFG is ∼10–20 cm−1 which limits ability to analyze vibrational line-shapes [2]. Finally a hybrid system was demonstrated where two separate laser sources — femtosecond and picosecond — were synchronized to achieve both very high spectral resolution (<1cm−1) and simultaneous spectral recording [3]. However the system required two complex independent synchronized laser systems which would be difficult to implement in most laboratories.

A new beam shaping technique implemented in 260 watt 1 kilohertz repetition rate picosecond pulse amplifier

We present a practical implementation of a novel beam shaping technique (based on spatially variable phase retardation plate inscription in fused silica glass by femtosecond pulses) in a high average power picosecond pulse amplifier.

Novel approach table-top vis-NIR OPCPA system

In this work we developed femtosecond tunable wavelength OPCPA system with a novel front-end. Picosecond all-in-fiber source is used for seeding DPSS pump laser and parametrical amplifier based white light supercontinuum generator. We measured up to 0.85 mJ and less than 40 fs pulses at the system output performing the wavelength tuning from 680 nm to 930 nm.

A new beam shaping technique implemented in 150 W 1kHz repetition rate picosecond pulse amplifier

We present a practical implementation of a novel beam shaping technique (based on spatially variable phase retardation plate inscription in fused silica glass by femtosecond pulses) in a high average power picosecond pulses amplifier.

High average power high repetition rate chirped pulse amplifier for OPCPA pumping

We present a high average power (~100W) picosecond pulses amplifier operating at 1 kHz repetition rate based on Nd:YAG active medium that should be an effective pump source for an OPCPA system.