Ultrafast thin-disk multi-pass amplifier system providing 1.9 kW of average output power and pulse energies in the 10 mJ range at 1 ps of pulse duration for glass-cleaving applications

Abstract

An ultrafast Yb-doped thin-disk multi-pass laser amplifier system with flexible parameters for material processing is reported. We can generate bursts consisting of four pulses at a distance of 20 ns and a total energy of 46.7 mJ at a repetition rate of 25 kHz. In single-pulse operation, 1.5 kW of average output is achieved at 400 kHz when optimizing for a beam quality of M 2 = 1.5. Alignment for maximum output power provides 1.9 kW at the same repetition rate. All results are obtained without chirped-pulse amplification in the multi-pass setup. The application potential of the system is demonstrated exploring its performance in materials processing of dielectrics. Cleaving of 3.8-mm-thick SCHOTT borofloat glass with a velocity of 1200 mm/s is demonstrated with 300 W of input power. Single-pass modification of 30 mm borosilicate glass is enabled with a Bessel beam at 1 kW of average power delivered by four-pulse bursts of an energy of 30 mJ.

The laser lightning rod project

“…In particular, large mode areas allow for high pulse energies at reasonable fluences while the short propagation distance through the gain medium keeps the nonlinearities low. With the advent of "cold" material processing and micromachining, the demand for powerful and highly energetic ultrashort pulsed lasers has pushed their development in the industrial domain, leading to commercial micromachining lasers with pulse energies up to several millijoules at repetition rates of hundreds of kHz, with pulse durations well below 1 ps [44,45]. Driven by the need for powerful pump lasers for optical parametric chirped pulse amplifiers (OPCPA), scientists applied the industrial thin-disk laser components to build ultrafast lasers aiming at tens of millijoules of pulse energy at repetition rates between 5-10 kHz [46].…”

Ultrafast thin-disk multipass amplifier with 720 mJ operating at kilohertz repetition rate for applications in atmospheric research

“…Stable propagation can also be achieved with a concatenation of resonator-like segments, however, at the cost of either small beam diameters at certain points along the propagation, or very long propagation distances [47,48]. Other approaches allow near-collimated propagation by balancing the beam divergence with a periodic focusing, which is provided by a well-chosen dioptric power of the thin-disk itself [39,49]. For our high-energy multipass amplifier, we designed a near-collimated propagation by means of refractive optics optimized for the thermal lens at the operation point.…”

“…To further reduce and compensate for the residual thermal drift during operation, piezo-controlled mirrors are used to actively stabilize the beam pointing inside the multipass amplifier. Concepts to overcome thermal effects such as non-absorbing monolithic all-glass reflection arrays [39] were disregarded in this laser system but may be implemented for future systems.…”

“…By circumventing a closed optical resonator, and hence making an optical switch redundant, this platform enables unmatched pulse energies at high repetition rates. Multi-kilowatt output powers have been demonstrated with CPA-free multipass amplifiers, applied for materials processing [39,40]. Pulse energies above 1 Joule have been attained in a CPA multipass scheme at a repetition rate of 100 Hz [41].…”

Monolithic thin-disk laser and amplifier concept

“…This design was quickly transferred to industrial applications: in 1997, Jenoptik produced the first commercial thin-disk laser, a 10 W Nd:YVO system; in 1999, Trumpf presented the first 1 kW thin-disk laser. In the following decades, thin-disk lasers addressed a large range of laser concepts and laser applications for science and industry-from high-power CW operation to sub-ps oscillators and amplifiers [4][5][6]. Currently, high-power thin-disk lasers with more than 10 kW out of one disk and good beam quality (sufficient for welding applications) are available [7].…”