Development of diode-pumped Alexandrite laser systems for atmospheric remote sensing
File(s)
Author(s)
Coney, Alexander Thomas
Type
Thesis
Abstract
The aim of this work is to produce a diode-pumped alexandrite proof-of-concept Master Oscillator Power Amplifier (MOPA) design for satellite-based lidar. Atmospheric remote sensing enables accurate weather predictions, climate change observations and detailed atmospheric topography. Current space-based lidar systems use diode-pumped Nd:YAG systems and are limited to the harmonics of 1064 nm, 532 nm and 355 nm. Alexandrite sources offer a range of operation from 720 nm - 820 nm. This allows lidar techniques such as resonance scattering to be used, providing more topographical data and profiling over a greater altitude range.
A diode-pumped alexandrite Q-switched oscillator is developed with a record-breaking pulse energy of 3.80 mJ. This involves multiple cavity designs and iterations. A diode-pumped seed oscillator is produced with an M-squared of 1.06 for amplifier characterisation. A novel amplifier design, the diamond geometry, is introduced. This produces the world's first diode-pumped alexandrite amplifier with a gain of 1.73. The multi-pass amplifier is experimentally optimised with seed wavelength and crystal temperature. The results are used to verify modelling based on a Frantz-Nodvik analysis.
The proposed diode-pumped alexandrite MOPA design consists of a single-longitudinal mode ring oscillator producing 5 mJ which seeds a two-stage amplifier, producing 50 mJ. The pre-amplifier and power amplifier are based on the diamond geometry. The proposed design is optimised for seed wavelength, crystal temperature, pump pulse duration and number of passes. The design is scalable, offering optimum operation at 750 nm but with a further option for 770 nm (potassium lidar).
A diode-pumped Nd:YAG MOPA is produced, enabling a comparison between alexandrite and current satellite-based lidar sources. The Q-switched zig-zag oscillator produces a pulse energy of 98 mJ. This is amplified to 265 mJ within a zig-zag amplifier. The system has been developed within Leonardo. This company developed the ALADIN laser launched in 2018.
A diode-pumped alexandrite Q-switched oscillator is developed with a record-breaking pulse energy of 3.80 mJ. This involves multiple cavity designs and iterations. A diode-pumped seed oscillator is produced with an M-squared of 1.06 for amplifier characterisation. A novel amplifier design, the diamond geometry, is introduced. This produces the world's first diode-pumped alexandrite amplifier with a gain of 1.73. The multi-pass amplifier is experimentally optimised with seed wavelength and crystal temperature. The results are used to verify modelling based on a Frantz-Nodvik analysis.
The proposed diode-pumped alexandrite MOPA design consists of a single-longitudinal mode ring oscillator producing 5 mJ which seeds a two-stage amplifier, producing 50 mJ. The pre-amplifier and power amplifier are based on the diamond geometry. The proposed design is optimised for seed wavelength, crystal temperature, pump pulse duration and number of passes. The design is scalable, offering optimum operation at 750 nm but with a further option for 770 nm (potassium lidar).
A diode-pumped Nd:YAG MOPA is produced, enabling a comparison between alexandrite and current satellite-based lidar sources. The Q-switched zig-zag oscillator produces a pulse energy of 98 mJ. This is amplified to 265 mJ within a zig-zag amplifier. The system has been developed within Leonardo. This company developed the ALADIN laser launched in 2018.
Version
Open Access
Date Issued
2019-12
Date Awarded
2020-05
Copyright Statement
Creative Commons Attribution NonCommercial Licence
Advisor
Damzen, Michael
Sponsor
Engineering and Physical Sciences Research Council
Publisher Department
Physics
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)