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C.-H. Kuo, X.-L. Ho, Y.-H. Wen, C.-Y. Cho, and Y.-C. Huang, ALPS 2026 (2026). LED pumping has attracted attention in solid-state lasers due to its long lifetime and reduced coherence-related issues compared with laser diodes. However, generating high-peak-power pulses from LED-pumped systems remains difficult because of the low brightness of LEDs. In this work, a MW-class LED-pumped electro-optic (EO) Q-switched solid-state laser was demonstrated for nanosecond ultraviolet generation. The laser operated at 1064 nm using an LED-pumped gain module combined with an EO Q-switch. Nanosecond pulses with durations of 10–20 ns and pulse energies exceeding 100 mJ were achieved, corresponding to peak power densities in the tens of MW/cm² range. Second-harmonic generation (SHG) converted the 1064 nm output to 532 nm, producing 25.2 mJ pulse energy from 89.12 mJ fundamental input energy. The generated SHG pulse width was approximately 11.5 ns. Fourth-harmonic generation (FHG) using a BBO crystal further converted the laser output to ultraviolet light near 265 nm with a pulse width of 10.47 ns. The results demonstrate that LED-pumped EO Q-switched solid-state lasers can support high-peak-power nanosecond operation and efficient nonlinear wavelength conversion for ultraviolet laser generation.

Y.-S. Yang, M.-H. Wu, X.-L. Ho, C.-H. Kuo, Y.-C. Huang, and C.-Y. Cho, Proc. SPIE 13698, 1369812 (2025). Conventional laser amplifiers are typically diode-pumped because LEDs suffer from low brightness and strong beam divergence. In this work, LED-pumped Nd:YAG nanosecond and picosecond laser amplifiers operating at 1064 nm were demonstrated. The nanosecond 4-pass amplifier generated more than 110 mJ pulse energy with a 10-ns pulse width, corresponding to peak powers above 11 MW. The optical conversion efficiency ranged from 1.5% to 3.3%. The picosecond regenerative amplifier, seeded by a mode-locked Yb:fiber laser, achieved 1.2 mJ output energy with an amplification gain near 2×10⁴. The amplified pulse width was approximately 20 ps, producing peak powers up to 60 MW. The system also demonstrated good beam quality (M² ≈ 1.35) and output energy stability within 3% over 40 minutes. These results show the potential of LED pumping for practical high-peak-power laser amplifier applications.

H.-R. Chiang, K.-Y. Huang, and Y.-C. Huang, OSA Laser Congress (ASSL/LAC) (2018). Continuous-wave (CW) operation in LED-pumped solid-state lasers is difficult because LEDs generate strong thermal loading and have low directional brightness. In this work, a CW 810-nm LED-pumped Nd:YAG laser with a thermal-isolated and light-guided pumping structure was demonstrated. The system used a 1%-doped Nd:YAG slab side-pumped by planar 810-nm LEDs. A glass slab was inserted between the LEDs and the gain medium to isolate heat while simultaneously guiding pump light into the crystal through total internal reflection. At 14-W pump power, the laser generated 370-mW CW output power with an optical efficiency of 2.6% and slope efficiency of 5.5%. By increasing the cavity length, stable single-transverse-mode operation was also achieved with a maximum output power of 248 mW. The results demonstrate that thermal isolation and guided LED pumping can enable practical CW operation of LED-pumped solid-state lasers and improve mode quality under continuous operation.

K.-Y. Huang, C.-K. Su, M.-W. Lin, Y.-C. Chiu, and Y.-C. Huang, Optics Express 24(11), 12043–12054 (2016). This work demonstrated an efficient 750-nm LED-pumped Nd:YAG laser using commercially available infrared LED arrays. Unlike conventional diode-pumped lasers, the moderately broadband LED spectrum overlaps well with the Nd:YAG absorption band, providing improved thermal and wavelength stability. The laser employed a slab-type 1%-doped Nd:YAG crystal side-pumped by planar 750-nm LED arrays. Sapphire plates were inserted between the LEDs and the gain crystal to improve thermal dissipation and support stable operation. For the linear-cavity configuration, the laser generated 37.5 μJ pulse energy with an optical efficiency of 1.36%, slope efficiency of 9%, and near diffraction-limited beam quality (M² = 1.1). Multi-pass V-cavity and Z-cavity configurations further increased the output energy to 346 μJ with optical efficiencies up to 3.4% and slope efficiencies up to 14%. The laser also demonstrated strong thermal stability, with output energy variation remaining within ±4.3% over a 5°C temperature range. The results highlight the potential of broadband LED pumping for stable, efficient, and scalable solid-state laser systems.