Raman lasers intracavity-pumped by semiconductor disk lasers

Rights statement
Awarding institution
  • University of Strathclyde
Date of award
  • 2012
Thesis identifier
  • T13338
Qualification Level
Qualification Name
Department, School or Faculty
  • Semiconductor disk lasers (SDLs) are efficient and commercially attractive devices as they can emit several Watts in continuous-wave (cw) operation, with good beam quality, low noise and great wavelength flexibility. SDL fundamental emission ranges from red to mid-infrared, while ultraviolet and other visible wavelength can be obtained via harmonic generation. This research shows that Raman conversion is an efficient way to extend the spectral coverage of well-established SDLs. The first experimental work consisted in the demonstration of a KGW Raman laser intracavity-pumped by a 1055 nm InGaAs SDL for laser emission at ~1.14 µm. This work represents the first Raman conversion of an SDL ever reported. Output power up to 0.8 W, broad wavelength tunability and cascaded Raman conversion (with low output coupling) were observed. The following experiment consisted in using synthetic single-crystal diamond as the Raman medium. In the last few years diamond has become a prominent Raman crystal as it provides high Raman gain, large Stokes shift and unrivalled thermal conductivity. A diamond Raman laser intracavity-pumped by an InGaAs SDL emitted up to 4.4 W at 1228 nm and was tuned from 1209-1256 nm. With an optical conversion efficiency exceeding 14%, this laser rivals the optical efficiencies of other cw Raman lasers and, perhaps more importantly, SDLs with direct emission at ~1.2 µm. Orange emission, with maximum output power of 1.5 W at 614 nm and wavelength tuning from 604.5-619.5 nm, was obtained via intracavity second harmonic generation in the Raman laser cavity. Raman conversion of a red-emitting GaInP SDL using a synthetic diamond crystal is also reported. As GaInP SDLs are less efficient than InGaAs SDLs, Raman threshold was more difficult to achieve, despite the Raman gain increasing for decreasing wavelengths. Nonetheless, Raman conversion in the deep red was observed, with output power of few tens of ~W, due to the low output coupling for the Raman laser, and tunable emission from 738-748 nm. This work is still at an early stage, so higher output power and enhanced laser efficiency may be achieved in future experiments.
Resource Type
Date Created
  • 2012
Former identifier
  • 967118