Thesis

Compact and low-cost ultrashort-pulse Ti:sapphire lasers

Creator
Rights statement
Awarding institution
  • University of Strathclyde
Date of award
  • 2022
Thesis identifier
  • T16224
Person Identifier (Local)
  • 201471432
Qualification Level
Qualification Name
Department, School or Faculty
Abstract
  • The subject matter of this thesis centres around the design and development of ultrafast Ti:sapphire lasers in a compact and low-cost context. Using 450 nm laser diodes as the pump source, both semiconductor saturable absorber mirror (SESAM) mode-locking and Kerr-lens mode-locking (KLM) techniques are used. Broad wavelength tunability while maintaining femtosecond pulse operation at 100’s of mW of average power and 10’s of kW of peak power was demonstrated. In the SESAM mode-locked configuration, a wavelength tunability range of 37 nm (788-825 nm) was demonstrated, with average output powers up to 433 mW, and with shortest pulse duration of 62 fs at 812 nm. In the KLM regime, a wavelength tunability range of 120 nm (755-875 nm) was demonstrated, with average output powers up to 382 mW, and with shortest pulse duration of 54 fs at 810 nm. Various cavity configurations were proposed and analysed with the intention of realising GHz pulse repetition rates in an ultrafast diode-pumped Ti:sapphire laser. Two different cavity configurations were chosen: KLM in a ring resonator configuration and SESAM mode-locking in a Z-shape standing-wave resonator configuration. Efficient continuous wave operation was achieved, however, mode-locked operation was not reached with either configuration. Graphene saturable absorbers for femtosecond pulse generation in diode-pumped Ti:sapphire were also investigated. Monolayer graphene samples were fully characterised in a differential transmission setup. This resulted in a saturation fluence of (41± 27) μJ/cm2, a saturable loss of (1.01 ± 0.15)% and a non-saturable loss of (0.42 ± 0.09)%, in broad agreement with values reported in the literature. The diode-pumped Ti:sapphire laser sources developed during the course of this thesis have demonstrated important performance parameters that bring them closer to matching the performance of their conventionally pumped counterparts, namely a wide wavelength tunability while maintaining femtosecond pulse operation at 100’s of mW of average power and 10’s of kW of peak power, suitable for many applications.
Advisor / supervisor
  • Lagatsky, Alex
  • Kemp, Alan
Resource Type
DOI

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