Single frequency vertical external cavity surface emitting lasers

Rights statement
Awarding institution
  • University of Strathclyde
Date of award
  • 2007
Thesis identifier
  • T11959
Qualification Level
Qualification Name
Department, School or Faculty
  • The thesis presents the development and implementation of single frequency vertical external cavity surface emitting lasers (VECSELs). Numerous cavity designs are reported, exploiting some unique features for single frequency operation. A small VECSEL cavity configuration is reported utilising a positive curvature mirror in reverse to create a 6mm cavity where the air gap between the mirror surface and VECSEL wafer act as an etalon, which induces single frequency operation. A 7nm tuning range has been shown with maximum output of 19.4mW. Thermal modelling was undertaken to analyse how the removal of the VECSEL's substrate could increase the thermal efficiency for high power operation. Another small cavity design of length 50mm was created, producing a high power, compact single frequency VECSEL. Using a birefringent filter and solid etalon single frequency operation was achieved. A tuning range of 1Onm was achieved with output powers of 271mW. Extensive mapping of the pump profile and eventual manipulation of this resulted in the M² of the laser of 1.1 being reduced to 1.02. In addition an air etalon system was constructed to eliminate walk-off losses experienced by the solid etalon. This resulted in a 20nm tuning range. Frequency doubling of an 850nm VECSEL using KNbO₃ is reported with 1.3mW of 425nm being achieved, corresponding to an efficiency of 3.2%/W. This system also incorporates a polarisation coupled pump system delivering 3W at 670nm from a 100μm fibre. The relationship between the VECSEL's gain and frequency conversion efficiency is also analysed in detail.
Resource Type
Date Created
  • 2007
Former identifier
  • 770338