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High power semiconductor lasers

Using red and near infra-red emitting quantum well and quantum dot based devices I have modelled the nearfield and farfield intensities and distribution in various waveguide structures. I compared the effect of various factors on the power density at catastrophic damage and found the greatest effect from the current pulse length and dot or well nature of the active region, for the first time in the AlGaInP material system. At short pulse length the quantum dot devices achieved a power density of 17 MW/cm<super>2</super> compared to 14 MW/cm<super>2</super> for quantum well lasers, and then proved by electron microscopy and photocurrent spectroscopy not to have reached their limit for mirror damage, but to have failed by other means. I observed the loss of optical power at catastrophic optical mirror damage in real time, applying single, very high current pulses, observing differences in the behaviour of quantum dot, which showed little or no facet damage, and quantum well devices, which showed large amounts of damage, with a resolution of tens of nanoseconds compared to microseconds in the literature. I proposed an explanation for the time taken for the power level to drop, which remained finite at about 200 ns in quantum well devices, in terms of the energy required to melt the observed quantity of damaged material.
Date January 2010
CreatorsElliott, Stella N.
PublisherCardiff University
Source SetsEthos UK
Detected LanguageEnglish
TypeElectronic Thesis or Dissertation

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