Characterization of thermal effects in diode-pumped nonlinear Neodymium-doped crystals

This study presents a comprehensive characterization of thermal effects in neodymium- doped (Nd-doped) YAG crystals (Nd:YAG) under diode- pumping configurations, along with a novel empirical way to evaluate efficiency of gain modules. To start, a technique for measuring focal lengths of a lens using...

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Detalles Bibliográficos
Autor: De Meester, Robin
Tipo de recurso: tesis de maestría
Fecha de publicación:2025
País:España
Institución:Universitat Politècnica de Catalunya (UPC)
Repositorio:UPCommons. Portal del coneixement obert de la UPC
Idioma:inglés
OAI Identifier:oai:upcommons.upc.edu:2117/452574
Acceso en línea:https://hdl.handle.net/2117/452574
Access Level:acceso abierto
Palabra clave:Diodes
Solid state physics
Thermal lens
Diode pumped solid-state laser
Shack-Hartmann wavefront sensor
Thermally induced birefringence
Pumping head
Gain module
Díodes
Física de l'estat sòlid
Àrees temàtiques de la UPC::Física::Física de l'estat sòlid::Propietats tèrmiques dels sòlids
Descripción
Sumario:This study presents a comprehensive characterization of thermal effects in neodymium- doped (Nd-doped) YAG crystals (Nd:YAG) under diode- pumping configurations, along with a novel empirical way to evaluate efficiency of gain modules. To start, a technique for measuring focal lengths of a lens using a Shack- Hartmann wavefront sensor is investigated and validated for measuring thermal lensing. A double validation is carried out, one by comparing the results with a better known technique and one by measuring the focal lengths of known lenses. Then, we investigate the thermal lensing phenomena arising from different configurations of pumped Nd:YAG crystals. First the evolution of the thermal lens effect with increasing pumping power is studied. Then, a comparison is performed of the thermal lensing effect with different doping concentrations, for various repetition rates of the pumping system and a comparison between thermal lensing in lasing and non- lasing conditions. Next, another thermal effect is studied, namely the depolarization of a beam traveling through the pumped crystal, both qualitatively and quantitatively. By calculating the thermal load from the thermal lens induced in the system, the power absorption in the system can be estimated and in this way we obtain an empirical way of evaluating the overall design and efficiency of a gain module.