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1. Radially Polarized
Lasers: Breaking the limit of diffraction
Focusing an incoming light into a smaller spot is always one
of the most interesting topics for optical engineers and scientists. This
is highly motivated by the large number of optical instruments and
devices that makes use of a sharply focused light beam. A tighter focus
means better resolution for applications such as lithography, laser
machining and confocal microscopy, and higher
storage density for optical data storage applications. It has been shown
experimentally that a radially polarized laser
beam, under suitable conditions, can be focussed
tighter than the diffraction limit. The project explores a novel method
to generate a high-power radially polarized
laser beam.
2. Tunable Solid State
Lasers:
Near-infrared pumped solid state lasers such as Cr:YAG and Cr:Forsterite are of interest because they enable the
implementation of broadly tunable continuous-wave sources or the
generation of short temporal optical pulses in the 1 micron to 1.6 micron
spectral range. This emission spectrum is useful as it covers the
telecommunication range. The project designs and builds a high power
tunable single longitudinal mode Cr:YAG
laser.
3. Diode Pumped Solid State
Laser:
Diode pumping of laser offers better efficiency and beam
quality than the flashlamp pumped
configurations. We have interests in exploring novel configurations of
diode pumping and the diode pumping of novel solid-state active media.
Our previous works on diode pumped solid state laser include Nd:YAG, Nd:YVO4, Nd:YALO, Tm:YAG, Yb:YAG and several Yb-doped
fiber lasers.
4. Nonlinear conversion of laser wavelength:
Optical Parametric Oscillator is a convenient method to
generate wavelengths that are not accessible by the solid state lasers.
We have interests and have spent substantial research effort in the
development of high power mid-IR Optical Parametric Oscillator based on
nonlinear optical crystals such as ZnGeP2, KTP, KTA, AgGaS2, and AgGaSe2.
5. Passive/Active locking of lasers:
Passive or active coherent locking of lasers promises large
laser power scalability. We are currently exploring a novel scheme of
coherent locking of several high power Nd
lasers.
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