Design and Characterisation of Blue Polymer Lasers
Author(s)
Wellinger, Thomas
Type
Thesis or dissertation
Abstract
Semiconducting polymers have attracted considerable attention as novel gain
materials for laser devices. An important future target in this context is
the realisation of a thin- film polymer laser diode. Since inorganic semiconductors
are amongst the most important devices in modern optoelectronic
technology, there is a lot of interest in achieving electrically pumped laser
action in organic semiconductors as a way to broadly tunable lasers covering
the whole visible spectrum and producing low-cost laser sources for optical
networks.
This thesis reports the results of a study on the design and characterisation of
optically pumped blue and violet emitting polymer lasers. The laser devices
are based on a range of materials belonging to the polyfluorene family of
conjugated polymers which generally show efficient, low threshold stimulated
emission. For future electrically pumped polymer lasers, a further reduction
of the threshold is crucial since a low threshold
fluence directly translates
into low current densities.
The optical properties of in total three
polyfluorene copolymers are investigated.
Lasers based on one of these copolymers are optically-pumped and
emission wavelength tuning is demonstrated by altering both grating period
and gain polymer thickness, allowing us to cover a part of the spectral region
between the blue and ultra-violet that has not been addressed yet by organic
semiconductor lasers.
Furthermore, a systematic numerical study of the optical environment on the
performance of blue emitting lasers on conducting DFB resonators is presented,
which is followed by a demonstration of optically-pumped polymer
lasers based on ITO gratings.
Finally, the results of a systematic study into optically pumped blue emitting
polymer lasers based on circular Bragg (CBR) resonators is reported. An
optimised design strategy is implemented and involves matching the grating
pro files with the nulls and maxima from the Bessel functions that represent
the radial distribution of the fi eld in a circular resonator.
materials for laser devices. An important future target in this context is
the realisation of a thin- film polymer laser diode. Since inorganic semiconductors
are amongst the most important devices in modern optoelectronic
technology, there is a lot of interest in achieving electrically pumped laser
action in organic semiconductors as a way to broadly tunable lasers covering
the whole visible spectrum and producing low-cost laser sources for optical
networks.
This thesis reports the results of a study on the design and characterisation of
optically pumped blue and violet emitting polymer lasers. The laser devices
are based on a range of materials belonging to the polyfluorene family of
conjugated polymers which generally show efficient, low threshold stimulated
emission. For future electrically pumped polymer lasers, a further reduction
of the threshold is crucial since a low threshold
fluence directly translates
into low current densities.
The optical properties of in total three
polyfluorene copolymers are investigated.
Lasers based on one of these copolymers are optically-pumped and
emission wavelength tuning is demonstrated by altering both grating period
and gain polymer thickness, allowing us to cover a part of the spectral region
between the blue and ultra-violet that has not been addressed yet by organic
semiconductor lasers.
Furthermore, a systematic numerical study of the optical environment on the
performance of blue emitting lasers on conducting DFB resonators is presented,
which is followed by a demonstration of optically-pumped polymer
lasers based on ITO gratings.
Finally, the results of a systematic study into optically pumped blue emitting
polymer lasers based on circular Bragg (CBR) resonators is reported. An
optimised design strategy is implemented and involves matching the grating
pro files with the nulls and maxima from the Bessel functions that represent
the radial distribution of the fi eld in a circular resonator.
Date Issued
2010-08
Online Publication Date
2011-01-05T09:41:53Z
Date Awarded
2010-12
Advisor
Bradley, Donal D. C.
Creator
Wellinger, Thomas
Publisher Department
Physics
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)