Characterization of Accumulated B-Integral of Regenerative Amplifier Based CPA Systems

Abstract

We report on a new approach to measure the accumulated B-integral in the regenerative and multipass amplifier stages of ultrashort-pulse high-power laser systems by B-integral-induced coupling between delayed test post-pulses and the main pulse. A numerical model for such non-linear pulse coupling is presented and compared to data taken at the high-power laser Draco with self-referenced spectral interferometry (SRSI). The dependence of the B-integral accumulated in the regenerative amplifier on its operation mode enables optimization strategies for extracted energy vs. collected B-integral. The technique presented here can, in principle, be applied to characterize any type of ultrashort pulse laser system and is essential for pre-pulse reduction.

Spectral-temporal Measurement Capabilities of Third-order Correlators

“…A systematic experimental investigation of the consequences and opportunities resulting from bandwidth restrictions in third order correlators was performed at the CPA1 probe beam installation of the Draco Petawatt laser system [29,30] shown in figure 3. The aim is to test the model for its ability to represent the third-harmonic spectrum and as a second step to characterize a chirped post-pulse as test case for the potential to measure and retreive spectral-temporal structures.…”

Millijoule ultrafast optical parametric amplification as replacement for high-gain regenerative amplifiers

“…For the system to be a real alternative for high-gain, one aspect of the design is to achieve similar output energies, which are often ranging from below 1 mJ, up to a few mJ for multistage, pre-amplification systems [16][17][18] . However, with respect to the replacement of regenerative amplifiers, parameters such as energy stability, beam quality and broadband gain are also relevant and should not be neglected.…”

Instantaneous Frequency Representation Used for CPA Laser Simulation

“…The main effect is the Kerr effect globally characterized by the B-integral. This effect's most deleterious impact on the temporal contrast is the pre-pulse generation from a post pulse by temporal diffraction [5,9,10]. Let's consider the two pulses of Fig.…”

“…5.b, these distortions modify the previously used simplified IFR where only linear chirp was applied. The pulse and its post-pulse will undergo the Kerr effect induced FWM dominantly induced by the amplifier materials [9].After amplification the pulses are recompressed by the compressor such that the main pulse is near-perfectly dispersion compensated and compressed as in the previous example.…”