Development of diode pumped Alexandrite lasers
File(s)
Author(s)
Sheng, Xin
Type
Thesis
Abstract
This thesis is focused on the development of diode-pumped Alexandrite lasers, especially in terms of understanding and optimizing their performance. Alexandrite possesses excellent physical properties and broad wavelength tunability (701-858 nm). Diode pumping of Alexandrite is a promising route to construct simple, compact and low-cost laser systems, which can enable a multitude of precision applications including remote sensing (LIDAR) light sources.
This thesis work presents the first demonstration of a Q-switched Alexandrite laser under CW diode pumping. The Q-switched laser was operated with pulse repetition rates up to 10 kHz. Pulses with maximum peak power of 1.19 kW were obtained at 1 kHz repetition rate. By modifying the already Q-switched laser system, a cavity-dumped Q-switched system was developed to generate shorter pulses. Pulses with considerably shorter duration of 2.9 ns and increased pulse energy of 200.8 μJ were produced. These correspond to a peak power of 69.2 kW which is more than 60 times that of the standard Q-switched operation.
This thesis also reports the first wavelength-tunable passively Q-switched diode-pumped Alexandrite laser using a semiconductor saturable absorber mirror (SESAM). The Q-switched wavelength tuning was achieved between 775 and 781 nm using a birefringent plate. Highly stable pulses with 73 mW average power, 6.9 μs pulse duration and 11.2 kHz repetition rate were obtained in fundamental TEM00 mode with excellent spatial quality (M2 < 1.1).
Lastly, the first single-longitudinal-mode (SLM) operation of a CW Alexandrite ring laser under diode pumping was presented in this work. An ultra-compact bow-tie ring cavity with astigmatic compensation was developed. The unidirectional operation of the ring laser was realized using an optical diode consisting of a Faraday rotator and a half-wave plate, which resulted in the SLM output with power >1 W in TEM00 mode. The wavelength was tuned between 727 and 792 nm. These successful pulsed and continuous-wave operations promote the prospect of diode-pumped Alexandrite lasers in light source applications.
This thesis work presents the first demonstration of a Q-switched Alexandrite laser under CW diode pumping. The Q-switched laser was operated with pulse repetition rates up to 10 kHz. Pulses with maximum peak power of 1.19 kW were obtained at 1 kHz repetition rate. By modifying the already Q-switched laser system, a cavity-dumped Q-switched system was developed to generate shorter pulses. Pulses with considerably shorter duration of 2.9 ns and increased pulse energy of 200.8 μJ were produced. These correspond to a peak power of 69.2 kW which is more than 60 times that of the standard Q-switched operation.
This thesis also reports the first wavelength-tunable passively Q-switched diode-pumped Alexandrite laser using a semiconductor saturable absorber mirror (SESAM). The Q-switched wavelength tuning was achieved between 775 and 781 nm using a birefringent plate. Highly stable pulses with 73 mW average power, 6.9 μs pulse duration and 11.2 kHz repetition rate were obtained in fundamental TEM00 mode with excellent spatial quality (M2 < 1.1).
Lastly, the first single-longitudinal-mode (SLM) operation of a CW Alexandrite ring laser under diode pumping was presented in this work. An ultra-compact bow-tie ring cavity with astigmatic compensation was developed. The unidirectional operation of the ring laser was realized using an optical diode consisting of a Faraday rotator and a half-wave plate, which resulted in the SLM output with power >1 W in TEM00 mode. The wavelength was tuned between 727 and 792 nm. These successful pulsed and continuous-wave operations promote the prospect of diode-pumped Alexandrite lasers in light source applications.
Version
Open Access
Date Issued
2019-09
Date Awarded
2020-02
Copyright Statement
Creative Commons Attribution NonCommercial NoDerivatives Licence
Advisor
Damzen, Michael John
Sponsor
Imperial College London
China Scholarship Council
Publisher Department
Physics
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)