The most technologically mature optically pumped semiconductor lasers (OPSL) are based on InGaAs quantum wells (QW) for emission in the 900-1200 nm range. The low wavelength boundary is set by both the bandgap of InGaAs and the most common pump wavelength of 808 nm. To extend the wavelength coverage into 700 – 900 nm, a different QW system and a different pump wavelength are needed. In this work, we present the progress and result in the development of AlGaAs-based OPSL.
We investigated cw intra-cavity third-harmonic generation (THG), where both the second- and third-harmonic NLO processes are type-I. The concept and results from a prototype with output of 28mW at 307nm are presented here.
Optically pumped semiconductor lasers (OPSL) have been replacing legacy gas lasers and solid state lasers for over a decade, due to their superior properties such as compactness, high efficiency, low noise, wavelength scalability, and power scalability. It has wide applications in life sciences, medical therapeutics, light show, and other scientific researches. In this work, we present a gain model and couple it to the thermal management of high power OPSL.
Self-heating of Optically Pumped Semiconductor (OPS) chip has been identified as the major limiting factor of power scaling in OPS-based lasers in continuous wave (cw) mode. In this work, characterization of OPS lasers in short pulse (100 ns) and low duty cycle (1%) regime, where self-heating is negligible, as a function of the heat sink temperature is presented. This data, combined with a rigorous thermal model, allows us to predict OPS chip performance in new cooling configurations for power scaling.
Optically pumped semiconductor lasers (OPSL) offer the advantage of excellent beam quality, wavelength agility, and high power scaling capability. In this talk we will present our recent progress of high-power, 920nm OPSLs frequency doubled to 460nm for lightshow applications. Fundamental challenges and mitigations are revealed through electrical, optical, thermal, and mechanical modeling. Results also include beam quality enhancement in addressing the competition from diode lasers.
Edge-pumping Nd:YAG laser gain media is a convenient method to couple pump power into a laser cavity. A difficulty with this geometry is that for uniformly doped materials, pump power deposited near the edge of the gain medium cannot be efficiently extracted by a diffraction-limited beam. However, ceramic Nd:YAG with smooth changes in neodymium doping level (doping profiles) can now be fabricated to ameliorate this problem. A slab engineered with a doping profile that has a higher concentration of Nd in the center, and less at the edges, would allow more pump power to be efficiently extracted by a diffraction-limited laser beam. Yet this solution poses its own problem because variations in Nd concentration introduce optical path length distortions that can significantly reduce beam quality. The variations in optical path length are predominantly from changes in the refractive index of the host due to Nd doping and spatially varying temperatures. A genetic-algorithm-based approach is presented that balances improvement in mode-overlap between excited state distribution and the signal laser beam against optical path length distortions. A doping profile was found for an edge-pumped, zig-zag slab amplifier that is expected to yield a 39% improvement in extracted power delivered into a diffraction-limited spot compared to a uniformly doped slab.
We report a 1.2 at. % Nd:YAG ceramic pumped with an 808-nm laser diode, placed in a
1.92-m cavity, and passively mode-locked at 1064-nm with a 1% modulation depth
SESAM. At a pump power of 11.1 W, this laser produced 2.6 W of average power with a
slope efficiency of 27%. The pulse length was 26 ps at a repetition rate of 78 MHz. The
ceramic exhibited no peak power degradation during a 20-hour test of doubling efficiency
with periodically-poled, near-stoichiometric lithium tantalate.