PhD Dissertation Defense Announcement (

Xiuping Xie xpxie at
Mon May 15 11:02:13 PDT 2006

Dear all,

I'm defending tomorrow and I thought that some of you may be interested in
the topic. Here are the details of my defense. Sorry if you receive this
message more than once.


Xiuping Xie

Research Advisor: Professor Martin M. Fejer

High Gain Parametric Processes in Quasi-Phase-Matched Proton-exchange
Lithium Niobate Waveguides

Tuesday 16 May, 2006
@ 1:00 pm
(Refreshments served at 12:45pm)

CIS Building, 101-X Auditorium


Developments in optical nonlinear materials and solid-state lasers led to
the rapid progress in nonlinear optics in recent years. Among the many
fields of nonlinear optics, c(2) parametric processes are among the major
tools for generating coherent radiation indispensable in optical
communication, spectroscopy and medical applications.

Involving short pulses with high peak power, high gain c(2) parametric
processes including optical parametric amplification (OPA) and optical
parametric generation (OPG) have been widely used for near- and
mid-infrared light sources, most of which so far have been demonstrated in
bulk materials. At the same time, waveguide devices can significantly
increase the parametric gain and have been widely applied in parametric
processes such as second harmonic generation. However a thorough study of
the usage of waveguides in high gain parametric processes is absent. This
thesis addresses the challenges in such applications and demonstrates how
quasi-phase-matched (QPM) gratings and waveguide structures can be tailored
to improve performance of high gain parametric processes.

We demonstrate high parametric gain for OPA in reverse-proton-exchange
lithium niobate waveguides with periodically-poled QPM gratings. Picojoule
OPG threshold with picosecond pump pulses near 780 nm is illustrated, which
is over two orders of magnitude lower than that in bulk crystals.
Furthermore we demonstrate control over the temporal properties of the
output products from OPG with picosecond pump pulses near 780 nm. By
synthesizing either the QPM gratings or the waveguide structures we
demonstrate one order of magnitude smaller time-bandwidth products at
designed wavelengths and obtain near transform-limited output from OPG. We
also illustrate mode demultiplexing for OPA using asymmetric Y-junctions,
in which the signal and idler in different waveguide modes are separated
with a contrast of >27.5 dB. The high gain parametric processes in
waveguides may therefore find more practical applications with the
engineerable QPM gratings and waveguide structures.


More information about the labmembers mailing list