OPCPA pump laser based on a regenerative amplifier with volume Bragg grating spectral filtering

Hybrid master oscillator power amplifier system providing 10 mJ, 32 W, and 50 MW pulses for optical parametric chirped-pulse amplification pumping

“…The MOPA system presented here is an upgraded secondgeneration version of our previous system [20], which produced 880 μJ at 2 kHz or 500 μJ at 10 kHz. Similar to [20], an ultrabroadband, few-cycle Ti:sapphire oscillator (Octavius-85M, MenloSystem, Inc.) is used as the front end and provides a seed at 1064 nm to optically synchronize the pump with the pulse to be amplified in the OPCPA.…”

“…The MOPA system presented here is an upgraded secondgeneration version of our previous system [20], which produced 880 μJ at 2 kHz or 500 μJ at 10 kHz. Similar to [20], an ultrabroadband, few-cycle Ti:sapphire oscillator (Octavius-85M, MenloSystem, Inc.) is used as the front end and provides a seed at 1064 nm to optically synchronize the pump with the pulse to be amplified in the OPCPA. The seed is first amplified to 0.85 mW, 10 pJ at 85 MHz in a fiber amplifier, consisting of 5 m, single-mode, Yb-doped fiber (Nufern, Inc., PM-YSF-HI) pumped by up to 1 W optical power (AlfaLight, Inc., AM4-976A-10-253), a 3 nm bandpass filter centered at 1064 nm (No-vaWave Technologies, PMBP-06-N-B-Q), and optical isolators (OFR Thorlabs Inc., IO-L-T980/I1053-65), which is similar to [21].…”

“…After this fiber stage, an electro-optic pulse picker (Quantum Technology, Inc., RT-3 and StarFire 2DR-25K-TX-15V) reduces the repetition rate to the 1-5 kHz range before seeding a regenerative amplifier. In comparison to [20], the regenerative amplifier is modified to provide higher pulse energies at 3 kHz repetition rate and is followed by a single-pass booster amplifier (Fig. 1).…”

“…This regenerative amplifier produces ∼2 mJ pulse energy (the saturation fluence is ∼21 mJ) at 1 kHz, ∼1.5 mJ (1.7% rms noise) at 3 kHz, or ∼0.8 mJ at 5 kHz. A volume Bragg grating (VBG) (OptiGrate, Corp.) narrows the spectral bandwidth in the regenerative amplifier to the 10-pm-linewidth level and thereby produces a transform-limited duration of 200 ps (FWHM) similar to [20,22]. In the current configuration, the 200 ps pulse duration is seen as a trade-off, similar to other MOPA systems [1,13,16,19,23,24], between a long pulse duration (several nanoseconds) for efficient power extraction from the solid-state amplifiers and the OPCPA application with an optimum duration of less than 100 ps.…”

“…No ASE is observed if the seed beam is blocked to the booster amplifier stage, due to the low gain and the distances between the amplifier modules. Furthermore, the regenerative amplifier has low ASE (due to the VBG [20]), and the output pulses of the single-pass show high contrast (>40∶1 ratio of main to single postpulse). As such, >97.5% of the total energy is in the main pulse.…”