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Femtosecond
Lasers
The objective of this project is to demonstrate the operation
of a variety of prismless and compact femtosecond lasers for
optical comb generation. Some of these will be diode pumped.
Laser systems will be created that generate optical combs
spanning 2/3 of an octave, one octave, and even 1.5 octaves.
Diode-pumped 10-30 fs lasers for optical comb generation will
also be constructed in a variety of microstructured fibers
an din novel highly nonlinear omniguides to be developed in
this program. In addition, the comb will be extended using
nonlinear optical crystals, highly efficient PPLN-structures,
and a 3:1 self-phase-locked optical frequency divider, also
to be developed in this program. These techniques will extend
the comb into the visible and permit self-referencing. Finally,
these combs generated directly from the laser will be stabilized
and locked, to the 1S-2S hydrogen transition as well as to
a cesium clock in order to use them for hydrogen spectroscopy
and to study the ultimate capabilities and limitations of
the different technologies.
Optical
Frequency Metrology with Ultracold Hydrogen
The objective of this project is the implementation of an
optical comb and the demonstration of a hydrogen clock. In
the first phase, an optical comb will be created in the range
of 650 - 1000 nm. The sideband spacing will be controlled
by an atomic clock. This phase of the project will also include
demonstration of spectroscopy of trapped hydrogen from the
2S state. The second phase of the project will involve increasing
the resolution of the 1S-2S signal and locking a self referencing
comb to it. The final phase will be the development of an
ultracold hydrogen apparatus with high collection efficiency,
suitable for optical clock applications.
Nonlinear
Optical Frequency Conversion
Quasi-phase-matched nonlinear optics can play a significant
role in improving and extending the performance of octave-wide
optical frequency combs (OOCs) by efficiently generating harmonic,
subharmonic, and auxiliary comb frequencies for OOC phase
locking and frequency referencing. Periodically-poled lithium
niobate is a highly nonlinear crystal that can be wavelength
tailored, via quasi-phase matching, for efficient second harmonic
generation, difference-frequency generation, and parametric
oscillation. This project will involve the design, fabrication,
and implementation of three such nonlinear optical devices:
a chirped-grating second harmonic generator; a chirped-grating
difference-frequency generator; and a self-phase-locked optical
frequency divider.
Novel
Nonlinear Mirrors
Nonlinear mirrors will be important components in robust femtosecond
laser systems. They can be designed to assure self-starting
of the modelocking process, they can play a role in improving
amplitude stability, and they can be used to lock two different
lasers together. This project will involve the design, engineering,
and fabrication of a variety of saturable absorber mirrors
for implementation in short pulse mode-locked laser systems.
Graded layers of AlGaAs, in which the aluminum fraction varies
at the interfaces, will be used in an approach that will provide
saturable absorber mirror structures with very wide bandwidth
and high reflectivity and with the appropriately designed
absorbing region. The focus of the project will involve high
index contrast mirrors composed of GaAs and oxidized AlAs.
Microstructured
Fibers
This project will investigate spectrally broadened combs produced
by propagation in microstructured fibers. Limits on comb frequency
range, limits on comb intensity and the influence of fiber
structure on comb stability will be examined. A variety of
microstructured fibers will be obtained, in addition to the
design, manufacture, and investigation of novel, highly nonlinear,
hollow core fiber fabricated at a new facility. The objective
will be to construct transmission fibers that will have strong
nonlinear properties.
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