Radiation laws must relate the fraction of incident radiation absorbed by an object and the amount of radiation emitted when it is hot so that objects can come to the same temperature just by exchanging electromagnetic radiation. Such laws are fundamentally important and set limits to practical applications such as in the conversion of light to electricity and in heat and thermal management generally. Kirchhoff’s classic results work well in many situations, but fail in others (specifically for “nonreciprocal” materials), and were derived using simplified models that do not apply to modern nanotechnology and light beams. We derive revised versions of laws that avoid these problems and discover additional and unexpected radiation laws that substantially expand the fundamental relations between optical absorption and emission.
This major review discusses the opportunities for the use of optics and optoelectronics to reduce the interconnect energies that dominate power dissipation in information processing and communications, showing how optics could make all interconnects inside even large machines behave like simple, low-energy local interconnects. It also summarizes the sources of energy dissipation inside machines, compares physical approaches to low-energy optoelectronic devices, and shows new opportunities for free-space optical systems to eliminate the electronic circuits responsible for most dissipation in interconnects.
How to design any linear optical device ... and how to avoid it
(See also a recent open Lecture on this topic)
We can think of many different optical components we might like to make but that we have not known how to design. A good example is a mode-splitter that could separate multiple overlapping beams without loss. Up till now, we have had to use techiques such as "blind" design by optimization or exhaustive search, and it has not generally been obvious whether the device we wanted was even possible physically. Now we show how to design any linear optical component; the method always works and actually requires no calculations at all.
Are optical transistors the next logical step?A transistor that operates with photons rather than electrons is often heralded as the next step in information processing, but optical technology must first prove itself to be a viable solution in many different respects. This article is a Commentary written for Nature Photonics, January 2010.
Quantum Mechanics Book
This introductory quantum mechanics text is published by Cambridge University Press. It is
intended both for physicists and for those from other
scientific and engineering disciplines, including electrical
and mechanical engineering, materials science, and
nanotechnology. The level of presentation is suitable for
junior undergraduates through graduate students to technical
professionals. Requirements for both physics and math are
minimized, and the necessary background in these areas is
summarized in appendices. Core topics are covered, the quantum
mechanics for key areas of application in electronic and
optical devices is explained, and advanced techniques and
areas, such as the quantum mechanics of light and quantum
information, are introduced.This is the textbook for both the EE222 and EE223 (Applied Quantum Mechanics I & II) classes at Stanford.
Device requirements for optical interconnects to chips
This invited paper for the July 2009 Special Issue on Silicon Photonics in the Proceedings of the IEEE discusses the targets and requirements for optoelectronics and optical devices if they are to meet the needs of future interconnects to chips. Energy per bit is particularly important, with 10 fJ/bit being a key device benchmark. The various approaches to optical and optoelectronic devices and technology are summarized and compared.
Fundamental limit to optical components We have derived an upper bound to the
possible performance of linear optical components of given
sizes and maximum dielectric constants. (Most downloaded article from all OSA journals other than Optics
Express, October 2007)See
also the Physical Review Letter on a
general limit to one-dimensional slow light structures and
a brief summary in Optics and Photonics
News "Optics in 2007"
Nanometallic-enhanced photodetectorsWe have demonstrated that nanometallic structures can enhance photodetection, promising very low capacitance optoelectronic devices compatible in size with CMOS transistors. A nanoscale C-shaped aperture in a metal can enhance the photocurrent in the semiconductor beneath it, and recently an optical analog of a Hertz dipole antenna concentrates light to a ~ 100 nm sized germanium detector element on a silicon substrate.
Quantum-confined Stark effect in germanium
quantum wellsA new modulation mechanism for
silicon-compatible optics, promising low energy devices for optical interconnects. See the Nature letter, a longer JSTQE paper on the original observations, the first modulator, a low-voltage C-band modulator, and a recent JSTQE paper on the detailed physics.
And, for something different How to become invisible!See also a brief introduction to this
invisibility at http://newsroom.spie.org/x5923.xml?highlight=x535