Frequency modified feedback in external cavity semiconductor laser systems

Rights statement
Awarding institution
  • Macquarie University.
  • University of Strathclyde
  • Scottish Universities Physics Alliance.
Date of award
  • 2014
Thesis identifier
  • T13834
Qualification Level
Qualification Name
Department, School or Faculty
  • This thesis presents work done on two external cavity semiconductor laser systems with different types of frequency modified feedback. The first system, based on a vertical-cavity surface-emitting laser (VCSEL) with feedback from a volume Bragg grating, is used to investigate the control of laser cavity solitons (LCSs). The temporal dynamics of a second system, relying on an edge-emitting semiconductor laser (EEL) with frequency-shifted feedback (FSF), is investigated. LCSs are trapped in local minima of a disorder potential landscape which is created by the growth induced inhomogeneities of the cavity resonance. The positions, frequencies and thresholds of the LCSs are dictated by the disorder and as a result LCSs appear at certain locations in the VCSEL aperture. These properties are used to demonstrate a method to quantitatively characterize the disorder in a VCSEL with frequency-selective feedback. LCSs, as any laser, have the freedom to choose their optical phase. The effects of disorder on the interaction of two LCSs are considered. We demonstrate frequency and phase synchronization of paired LCSs as their relative detuning is varied. In both theory and experiment the locking behavior is well described by the Adler model for the synchronization of coupled oscillators. In the case of the second system, dynamics of the output of an EEL with FSF is systematically and comprehensively measured for the first time. Three fundamentally different regimes of operation are identified corresponding to low, medium and high levels of FSF. Low levels of FSF cause the emission spectrum to broaden. Medium levels of FSF are consistent with those found in semiconductor with conventional feedback systems. High levels of FSF result in periodic oscillations on a cw baseline which is similar to the pulsed comb of mode output observed in analogous FSF systems using solid state gain media when the FSF is resonant.
Resource Type
Date Created
  • 2014
Former identifier
  • 1039390