Optimising the efficiency of pulsed diode pumped Yb:YAG laser amplifiers for ns pulse generation

Abstract

We present a numerical model of a pulsed, diode-pumped Yb:YAG laser amplifier for the generation of high energy ns-pulses. This model is used to explore how optical-to-optical efficiency depends on factors such as pump duration, pump spectrum, pump intensity, doping concentration, and operating temperature. We put special emphasis on finding ways to achieve high efficiency within the practical limitations imposed by real-world laser systems, such as limited pump brightness and limited damage fluence. We show that a particularly advantageous way of improving efficiency within those constraints is operation at cryogenic temperature. Based on the numerical findings we present a concept for a scalable amplifier based on an end-pumped, cryogenic, gas-cooled multi-slab architecture.

DiPOLE: A multi-slab cryogenic diode pumped Yb:YAG amplifier

“…Polycrystalline ceramics have emerged as a potential candidate for high-energy lasers [4] as they can be fabricated in large sizes, whilst retaining large damage thresholds and excellent thermal properties. In particular, ceramic Yb:YAG shows excellent thermal properties with high emission and absorption crosssections resulting in saturation fluence as low as ~13 J/cm 2 at 300 K. The efficiency of Yb-doped systems can be significantly improved by operating at cryogenic temperatures, eliminating reabsorption loss and relaxing the pumping requirements [5]. Moreover, cryogenic operation increases the emission and absorption cross-sections, resulting in a further reduction of the saturation fluence (~2 J/cm 2 at 175K for Yb:YAG) and enhancing the gain.…”

Laser diode stacks: pulsed light power for nuclear fusion

“…In agreement with the Yb pumping application, this device is characterized at τ = 1 ms [18] . The conversion efficiency at the operating point of 500 W is 53%.…”

Design of a kJ-class HiLASE laser as a driver for inertial fusion energy

“…The following figures give an indication of the evolution of the In this case, the input beam can be provided by nextgeneration high-energy-class (HEC)-DPSSL facilities with output energies in the range of 100-150 J [8,12,13] .…”

“…It uses multiple thin slabs of Yb 3+ :YAG Correspondence to: Antonio Lucianetti, Institute of Physics, AS CR, Na Slovance 2, 182 21 Prague, Czech Republic. Email: lucianetti@fzu.cz gain medium, face-cooled with high-pressure streaming helium gas [12,13] . The goal of this paper is to provide an amplifier design for the kJ-class laser architecture that minimizes accumulated nonlinear phase (B integral), thermally induced wavefront aberrations and stress birefringence.…”