Ultra-broadband Optical Parametric Chirped-pulse Amplification Research Articles

Effect of the pump beam profile and wavefront on the amplified signal wavefront in optical parametric amplifiers.

We present a theoretical and experimental analysis of the signal phase introduced by the pump-beam wavefront and spatial profile during optical parametric amplification (OPA) process. The theory predicts the appearance of an additional wavefront in the amplified signal beam that is proportional to the spatial derivative of the pump-beam wavefront. The effect of the pump-beam profile on the signal-beam wavefront is also investigated. Our experiments tested these theoretical predictions by comparing the wavefront of the signal beam before and after amplification in a multi-joule broadband OPA. The measured signal wavefront was shown to have the expected dependence on the pump-beam profile and wavefront. These results can be considered when designing petawatt-scale ultrabroadband optical parametric chirped-pulse-amplification systems.

Analysis of pump-to-signal noise transfer in two-stage ultra-broadband optical parametric chirped-pulse amplification.

In optical parametric chirped-pulse amplification (OPCPA), pump temporal intensity modulation is transferred to the chirped-signal spectrum via instantaneous parametric gain and results in contrast degradation of the recompressed signal. We investigate, for the first time to our knowledge, the pump-to-signal noise transfer in a two-stage ultra-broadband OPCPA pumped by a single laser and show the dependence of pump-induced signal noise, characterized both before and after pulse compression, on the difference in pump-seed delay in the two stages. We demonstrate an up-to-15-dB reduction of the pump-induced contrast degradation via pump-seed delay optimization. Experiments and simulations show that, even when parametric amplifiers are operated in saturation, the pump-seed delay can be used to minimize the pump-induced contrast degradation that is attributed largely to the noises from the unsaturated edges of the pulse and that of the beam.

Ultra-broadband high conversion efficiency optical parametric chirped-pulse amplification based on YCOB crystals.

We present a high efficiency and ultra-broadband optical parametric chirped-pulse amplification (OPCPA) system fully based on yttrium calcium oxyborate (YCOB) crystals. The OPCPA properties of YCOB at 808 nm are studied for both high gain and saturated amplification. The non-collinear angle is finely tuned to study the variation of gain spectrum at a certain phase-matching angle of YCOB crystals. After amplification by four YCOB crystals, a total signal gain of 0.9×109 is obtained and the FWHM spectral bandwidth is still over 100 nm. An amplified signal pulse of 182 mJ is achieved with pump energy of 440 mJ in the saturated amplification stage and the conversion efficiency is about 40%. After a four-grating compressor, a pulse duration of 20 fs is measured by a second-order autocorrelator.

75 MW few-cycle mid-infrared pulses from a collinear apodized APPLN-based OPCPA

We present an ultra-broadband optical parametric chirped-pulse amplification (OPCPA) system operating at 3.4 µm center wavelength with a peak power of 75 MW. The OPCPA system is split into a pre- and a power-amplifier stage. Both stages are based on apodized aperiodically poled MgO:LiNbO3 (APPLN). The collinear mixing configuration allows us to manipulate the spectral phase of the output mid-infrared pulses by sending the near-infrared seed pulses through a pulse shaper. The system delivers clean 75-fs pulses with record-high 700 mW average power, corresponding to 7 µJ of pulse energy at a repetition rate of 100 kHz.

Ultrabroadband optical parametric chirped-pulse amplifier using a fan-out periodically poled crystal with spectral spatial dispersion

Based on the full two-dimensional characteristics of the quasi-phase-matched fan-out periodically poled crystal, a scalable and engineerable scheme for ultrabroadband optical parametric chirped-pulse amplification is proposed, which can significantly broaden the gain bandwidth by the spatial separation of different frequency components of the signal pulse and manipulation of the distribution of the pump beam along the fan-out direction of the crystal. The theoretical analysis shows that the signal pulse can be amplified with minimal spectrum narrowing, and the initial spectrum can be broadened considerably if needed. Based on this scheme, using a fan-out periodically poled $5%$ mol MgO-doped congruent lithium niobate with a configuration of $5\ifmmode\times\else\texttimes\fi{}0.5\ifmmode\times\else\texttimes\fi{}5 {\mathrm{mm}}^{3}$ and two pump beams, the $3.3\ensuremath{-}\ensuremath{\mu}$m middle-infrared ultrabroadband optical parametric chirped-pulse amplifier is designed. The numerical computation results confirm that the $\ensuremath{-}3$ dB gain bandwidth of this amplifier exceeds 320 nm and can be further broadened.

Controlling the phase matching conditions of optical parametric chirped-pulse amplification using partially deuterated KDP

Using a partially deuterated KDP crystal for an optical parametric amplifier, we demonstrated ultrabroadband optical parametric chirped-pulse amplification of more than 250 nm bandwidth at a center wavelength of 1050 nm. We numerically show how to control the broadband phase matching conditions at different wavelengths to match center wavelengths of suitable broadband seed sources by adjusting the deuteration level in partially deuterated KDP.

Spectral broadening and compression to few-cycle pulse widths in the regime of soliton-self-frequency shift

Soliton-self-frequency shift in fibers with a precisely controlled dispersion is shown to enable efficient spectral broadening and temporal compression of light fields to few-cycle pulse widths. Anomalously dispersive fibers with positive third-order dispersion can transform nano- and subnanojoule 100-200 fs laser pulses into smoothly wavelength-tunable and spectrally broadened solitons with a pulse width as short as two to five field cycles. This regime of soliton pulse transformation is ideally suited for the creation of compact frequency-tunable fiber sources as well as for ultrabroadband optical parametric chirped-pulse amplification with an optical synchronization between the pump and seed fields.

Bandwidth Enhancement of Optical Parametric Chirped Pulse Amplification by Temporally Delayed Two Pump Beams

We have demonstrated ultra-broadband optical parametric chirped-pulse amplification of more than 350 nm bandwidth in the near-infrared region. We have observed a substantial enhancement (nearly 2-fold) of the parametric amplification bandwidth by using time-delayed two broadband pump pulses at degeneracy.

Short-pulse optical parametric chirped-pulse amplification for the generation of high-power few-cycle pulses

We report ultrabroadband optical parametric chirped-pulse amplification (OPCPA) with an output pulse energy of up to 250 μJ from an OPCPA stage pumped by short pulses of ∼100 fs duration at 395 nm wavelength. In order to generate ultrahigh-power pulses in the few-cycle regime, such a short-pulse-pumped OPCPA scheme appears to be a promising route, by virtue of its inherently advantageous features. Firstly, the stretching and compression fidelity as well as the pulse contrast are increased due to the short pump- and seed-pulse durations. Additionally, the higher pump powers allow for using thinner OPA crystals, thereby increasing the amplification bandwidth that will support even shorter pulse durations. We present experimental results where the effective bandwidth of the seed pulses was increased in the OPCPA process resulting in a shortened transform-limited pulse duration in addition to the energy gain. The amplified pulses from OPCPA have been compressed to the sub-10-fs, few-cycle range by using chirped mirrors. Scaling of this short-pulse-pumped OPCPA technique for few-cycle-pulse generation to the highest (TW–PW) power levels is also planned (Petawatt Field Synthesizer project at the Max-Planck-Institut für Quantenoptik).

Ultra-broadband optical parametric chirped-pulse amplification using an Yb: LiYF_4 chirped-pulse amplification pump laser

We demonstrate ultra-broadband optical parametric chirpedpulse amplification of 300-nm bandwidth pumped by a broadband pulse delivered from a diode-pumped, cryogenically-cooled Yb:YLF chirped- pulse amplification laser.

Ultra-Broadband Optical Parametric Chirped-Pulse Amplification with a Diverged Pump Beam

Ultra-Broadband Optical Parametric Chirped-Pulse Amplification with a Diverged Pump Beam

Ultra-broadband optical parametric chirped-pulse amplification by matching of both group-velocity and pulse-front

Ultra-broadband optical parametric chirped-pulse amplification is analyzed based the compensation of phase-mismatch, which is achieved by matching of both group-velocity and pulse-front between signal and idler by the combination of the noncollinear-phase-match and pulse-front-tilt. The results show exactly matching of both group-velocity and pulse-front is the important criterion for constructing an UBOPCPA. Its general model is developed, in which the group velocities, noncollinear angles, spatial walk-off angles, linear angular spectral dispersion coefficients and pulse-front tilted angles are suitably linked to each other. Finally, specific numerical calculations and simulations are presented for β-barium borate OPCPA with type-I noncollinear angularly dispersed geometry.