The aim of this thesis is to contribute to the understanding of
the dynamics of semiconductor lasers on a 10 to 100 ps time scale when
their output is altered by external feedback. The optimization of
parameters involved in optoelectronic feedback results in a reduction in
the measured minimum pulse FWHM relative to previous work, and gives the
conditions necessary to produce 25 ps FWHM optical pulses using this
technique. To aid in the understanding of the modelocking of diode lasers,
the CW spectral and threshold characteristics of a diode laser coupled to
a mirror external cavity are examined. It is found that multiple reflections
in the compound cavity cause an increase:). in mode linewidth with increasing
bias current up to a maximum for a particular level of feedback for an
external mirror coupled laser, but not for a grating coupled laser. As
a result of the CW optical feedback analysis, grating feedback is
utilized as a probe of the laser gain in a refinement of a previously
reported technique for direct gain measurement. Also, the total loss
reduction induced by external optical feedback is found to be made up
of the sum of mirror loss and mode propagation loss reductions. This
has significance in simulations of active modelocking and injection
locking tuning characteristics carried out in this work. Simulations
for active modelocking of a diode laser with low residual facet reflectivity
in. an external mirror cavity account for the previously unexplained extreme sensitivity of the modelocking process to oscillator stability.
Grating external cavity injection locking experiments and simulations
present a new scheme for obtaining nearly transform limited optical
pulses using semiconductor lasers. / Thesis / Master of Engineering (ME)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/29250 |
| Date | 08 1900 |
| Creators | Kempf, Paul H. G. |
| Contributors | Garside, B. K., Engineering Physics |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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