Advanced Alexandrite lasers and technology
File(s)
Author(s)
Xiao, Huaifeng
Type
Thesis
Abstract
Alexandrite has attracted great attention as a laser gain medium owing to its broad wavelength tunability in near infra-red (NIR) range and excellent properties. This work is aimed to develop new technologies of Alexandrite lasers to fulfill further needs of applications. }
Red-diode-pumped continuous-wave (CW) Alexandrite lasers are presented with different cavity designs and pumping arrangements. Laser outputs with high power, high spatial quality and tunable wavelength are demonstrated.
Deep study for pumping-induced lensing effect of Alexandrite is performed. A full theory of lensing strength and transient response is developed and shows excellent agreement with the experimental results under different conditions, for example, pumping lenses, crystal types, and temperature. This transient analysis provides a new method to separate the two lensing components, thermal and population lensing, in Alexandrite lasers.
The potential of blue diodes to be applied in Alexandrite lasers as pumping sources is explored. Record power from a blue-diode-pumped Alexandrite laser is obtained, and the analysis about the pumping-induced lensing effect is also performed. The difference in lensing performance provides a comparison with red-pumping for further understanding in the lensing mechanism.
Nonlinear optical frequency conversion of diode-pumped Alexandrite lasers has been demonstrated using both external-cavity and intra-cavity generation. Pulsed ultra-violet (UV) second harmonic generation (SHG) with beam quality improvement is conducted with the walk-off compensation technique from a diode-pumped Alexandrite laser. World-first deep-UV laser pulses from third harmonic generation (THG) are subsequently demonstrated from a diode-pumped Alexandrite laser with 30 μJ pulse energy and 19.1% total conversion efficiency. CW UV output from diode-pumped Alexandrite through intra-cavity SHG is also shown in this work. A record CW UV laser with maximum output power of 5.05 W and wide wavelength tunable range from 364 nm to 402 nm is achieved.
Red-diode-pumped continuous-wave (CW) Alexandrite lasers are presented with different cavity designs and pumping arrangements. Laser outputs with high power, high spatial quality and tunable wavelength are demonstrated.
Deep study for pumping-induced lensing effect of Alexandrite is performed. A full theory of lensing strength and transient response is developed and shows excellent agreement with the experimental results under different conditions, for example, pumping lenses, crystal types, and temperature. This transient analysis provides a new method to separate the two lensing components, thermal and population lensing, in Alexandrite lasers.
The potential of blue diodes to be applied in Alexandrite lasers as pumping sources is explored. Record power from a blue-diode-pumped Alexandrite laser is obtained, and the analysis about the pumping-induced lensing effect is also performed. The difference in lensing performance provides a comparison with red-pumping for further understanding in the lensing mechanism.
Nonlinear optical frequency conversion of diode-pumped Alexandrite lasers has been demonstrated using both external-cavity and intra-cavity generation. Pulsed ultra-violet (UV) second harmonic generation (SHG) with beam quality improvement is conducted with the walk-off compensation technique from a diode-pumped Alexandrite laser. World-first deep-UV laser pulses from third harmonic generation (THG) are subsequently demonstrated from a diode-pumped Alexandrite laser with 30 μJ pulse energy and 19.1% total conversion efficiency. CW UV output from diode-pumped Alexandrite through intra-cavity SHG is also shown in this work. A record CW UV laser with maximum output power of 5.05 W and wide wavelength tunable range from 364 nm to 402 nm is achieved.
Version
Open Access
Date Issued
2025-08-21
Date Awarded
01/11/2025
License URL
Advisor
Damzen, Michael J
Publisher Department
Department of Physics
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)