SSO Seminar
Wednesday, April 18, 2012 - 16:00 to 17:00
Weniger 304
Event Speaker: 
Dr. Alan Wang
Local Contact: 
Yun-Shik Lee

Nano‐photonic devices are playing increasingly important roles in optical communication and
optical sensor systems. By engineering the nano‐photonic structures, for example, by fine tuning
the photonic band diagram of photonic crystal waveguides, one can slow down the
group velocity of the photons by two orders of magnitude, which can significantly increase the
light‐matter interaction. In this presentation, I will discuss the design and fabrication of an
innovative photonic crystal slot waveguide on silicon‐on‐insulator (SOI) wafers, with special
emphasis on coupling light from conventional optical fibers into slow light enhanced nanophotonic

Based on this ultra‐efficient platform, we have developed highly compact (300μm) and ultrasensitive
on‐chip optical sensors for water quality monitoring (50ppb xylene in water) and
green‐house gas detection (100ppm methane in nitrogen). When the slow light enhanced nanophotonic
waveguide is combined with other innovative materials, we can create various
photonic devices with enhanced functionalities for a broad spectrum of applications in board
level optical interconnect, radio frequency (RF) photonic communication, electromagnetic wave
detection, and bio‐molecule sensing. I will show the state‐of‐the‐art design of a nano‐photonic
modulator using E‐O polymer infiltrated silicon photonic crystal slot waveguide with
unprecedented efficiency, and experimental demonstration of 735pm/V in‐device E‐O
coefficient and 0.44V‐mm of VπL, which is ten times better than the best results of our
competitors. The application of photonic bandgap nano‐devices for surface enhanced Raman
scattering is also demonstrated to achieve 10 times additional enhancement factors.

In summary, photonic bandgap nanodevices have demonstrated extremely high potential in
many communication and sensing areas, and will continue to broaden its application in many
emerging fields through interdisciplinary research.