PhD Orals -- Maria Makarova, Thursday, October 1, 2009

Maria Makarova makarova at
Fri Sep 25 09:54:26 PDT 2009

Department of Electrical Engineering
University PhD Dissertation Defense

Silicon-based photonic crystal light sources
Maria Makarova
Advisor: Prof. Jelena Vuckovic

Time:  Thursday, October 1st, 10:00 am (refreshments at 9:45)
Location:  CIS-X Auditorium


Efficient light generation on silicon is desirable for a variety of
applications because of its low fabrication cost relative to III/V
semiconductors and because it will enable monolithic integration with
electronic components on the same Si platform.  We studied
silicon-rich silicon nitride with emission in the visible and
erbium-doped silicon nitride (Er:SiNx) with emission at 1540 nm.  Both
of these materials are compatible with the mainstream complementary
metal-oxide semiconductor (CMOS) processing technology. In this talk,
I will discuss our results on using photonic crystal (PC) cavities to
enhance luminescence from these materials. Nano-resonators modify the
local optical density of states (DOS) to enhance the emission in a
fundamentally different way than what is accessible through materials
engineering. Specifically, photon emission rate can be enhanced at a
particular wavelength because the optical DOS is higher at the cavity
resonance, which in turn improves efficiency and allows faster
modulation rates.  We have demonstrated up to 11-fold enhancement at
photonic crystal resonance relative to smooth film at 730 nm and
30-fold enhancement at 1540 nm.  Most recently, we have observed
cavity line-width narrowing with increasing pump power in the
erbium-doped sample, resulting from decrease in ground-state
absorption by erbium ions as more of them are excited.  We achieved
excitation of up to 28% of Er ions at cryogenic temperature.   This is
an important step toward realizing a laser based on Er:SiNx in the
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