Robust Self-Referenced Generator of Programmable Multi-Millijoule THz-Rate Bursts

Abstract

The generation of ultrashort laser pulse bursts has already contributed to many applications such as materials processing [1] , pulsed laser deposition [2] , laser induced breakdown spectroscopy (LIBS) [3] and seeding of free electron lasers [4] . Currently, there is a rising demand on burst sources providing terahertz (THz) intraburst repetition rates or higher corresponding to pulse spacings in the order of a few picoseconds, given by applications such as resonant driving of optical nonlinearities [5] , time-resolved nonlinear spectroscopies [6] , coherent control of quantum systems [7] or as driver for secondary radiation sources, e.g. generation of THz bursts [8] . However, the amplification of bursts to multi-millijoule energies at THz intraburst repetition rates is highly problematic. This is given by the appearance of spectral modes that are mapped into the time-domain, formed by spectral interference of closely spaced pulses which are overlapping when applying Chirped Pulse Amplification (CPA). This leads to insufficient energy extraction in an amplifier and, if pulse spacing is not stabilized on an interferometric scale, to temporally unstable burst generation. Recently, we have successfully demonstrated energy-safe, stabilized CPA of ultrashort pulse bursts with THz intraburst frequencies up to multi-millijoules by applying Vernier-enabled phase-modulation techniques, breaking the mentioned energy-limiting barrier [8] . In this contribution, we demonstrate a new version of our burst-generation technique, which drastically lowers system complexity compared to our previous approach, allowing its application to any master-oscillator regenerative-amplifier combination setup with only minor modifications.