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|Title: ||Active microring and microdisk optical resonators on indium phosphide|
|Authors: ||Amarnath, Kuldeep|
|Advisors: ||Ho, Ping-Tong|
|Department/Program: ||Electrical Engineering|
|Sponsors: ||Digital Repository at the University of Maryland|
University of Maryland (College Park, Md.)
|Keywords: ||Engineering, Electronics and Electrical (0544)|
Physics, Optics (0752)
microring microdisk optical switching nonlinear semiconductor
|Issue Date: ||27-Apr-2006|
|Abstract: ||Photonic or optical logic holds the promise of ultra-fast logic circuits with
capability for speeds beyond what is possible using conventional silicon electronics.
However, the jump from theory to practice has a high barrier set by critical issues such as
integration, scalability and power requirements. Optical micro-resonator based schemes
have the potential of addressing some of these issues. This thesis focuses on the
development of active InGaAsP/InP microdisk and microring optical resonators to lower
that barrier a little.
Microrings and disks provide a compact and cascadable device platform to
achieve resonance enhancement of optical non-linearity. By incorporating gain in such
devices, the optical power needed for carrying out switching can be greatly reduced.
Electrically pumped microring and microdisk resonators are fabricated on indium
phosphide in both vertically and laterally coupled bus-waveguide configurations. The
gain saturation non-linearity is used to demonstrate all-optical switching and bistable
operation at optical powers more than two orders of magnitude lower compared to
passive devices. The shift in the ring/disk resonances caused by the refractive index
change due to a pump beam is used to switch a weaker probe beam tuned to one of the
resonances. The non-linear response and switching mechanism is modeled numerically.
A novel pseudodisk configuration that combines the best of microdisks and microrings is
used to minimize device heating and surface recombination as well as provide near
Additionally, optical amplifiers based on microrings are also developed for
cascading passive optical gates. Optical amplification up to 10 db in pulsed mode has
been observed for 20 µm radius microrings.
The control of surface recombination on the microring sidewalls is critical to
avoid carrier loss and device heating. A sulfur passivation scheme is used to reduce the
surface recombination velocity. The lateral carrier transport and surface recombination in
microrings is analyzed by an ambipolar diffusion model.|
|Appears in Collections:||UMD Theses and Dissertations|
Electrical & Computer Engineering Theses and Dissertations
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