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|Title: ||One- and two-photon pumped organic semiconductor lasers|
|Authors: ||Tsiminis, Georgios|
|Supervisors: ||Turnbull, Graham A.|
Samuel, Ifor D. W.
|Issue Date: ||2010|
|Abstract: ||This thesis describes a number of studies on organic semiconductors focused
around using them as gain media for lasers. The photophysical properties of
organic semiconductors are studied using a wide range of experimental
techniques, allowing the evaluation of new materials and novel excitation
schemes for use in organic semiconductor lasers.
Polyfluorene is a well-established conjugated polymer laser gain medium and in
this thesis its excellent lasing properties are combined with its two photon
absorption properties to demonstrate a tunable two-photon pumped solid-state
laser based on a commercially available organic semiconductor.
A family of bisfluorene dendrimers was studied using a number of
photophysical techniques to evaluate their potential as laser materials.
Distributed feedback lasers based on one of the dendrimers are demonstrated
with lasing thresholds comparable to polyfluorene. The same materials were
found to have enhanced two-photon absorption properties in comparison to
polyfluorene, leading to the fabrication of tunable two-photon pumped
A member of a novel family of star-shaped oligofluorene truxenes was
evaluated as a laser gain material and the distributed feedback lasers made from
them show some of the lowest lasing thresholds reported for organic
semiconductors, partly as a consequence of exceptionally low waveguide losses
in comparison to other single-material thin films.
Finally, an organic laser dye is blended with a conjugated polymer, where the
dye molecules harvest the excitation light of a GaN laser diode and transfer its
energy to the polymer molecules. This is the first time such a scheme is used in
an organic laser and in combination with a novel surface-emitting distributed
Bragg reflector resonator allows the demonstration of a diode-pumped organic
laser, a significant step towards simplifying organic lasers.|
|Publisher: ||University of St Andrews|
|Appears in Collections:||Physics & Astronomy Theses|
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