It is demonstrated that waveguide eigenmodes with a rotating phase may exert a longitudinal force, positive
or negative, as well as a torque on the guiding structure or part of it. A general formulation of the linear and
angular momentum currents flowing in the waveguide is given. Several examples are considered, including a
lossy dielectric cylinder bounded inside a hollow waveguide, and a lossy dielectric fiber. The results of this study
may be used for a novel type of light driven rotating machines.
We report the first experimental evidence for direct particle acceleration by stimulated emission of radiation (PASER)
namely, energy stored in microscopic cavities such as molecules, that otherwise may be used to amplify radiation, may
be directly utilized for acceleration of a train of electron micro-bunches. In the framework of this proof-of-principle
experiment, conducted at the Brookhaven National Laboratory, a 45MeV electron macro-bunch was modulated by its
interaction with a high-power CO2 laser pulse, within an adequate wiggler, and then injected into an excited CO2 gas
mixture. The emerging micro-bunches experienced a 0.15% relative change in the kinetic energy, in a less than 40cm
long interaction region. Both the fundamental frequency of the train of micro-bunches and the active medium main
resonance frequency are matched. This proof-of-principle experiment demonstrates, for the first time ever, the feasibility
of coherent collisions of the second kind i.e., a particle analog of the laser.
This tutorial focuses on the new opportunities that may be harnessed when the operating wavelength of acceleration
structures is reduced by more than 5 orders of magnitude from tens of centimeters to a fraction of a micro-meter. On the
one hand, we show how a Bragg waveguide may be adapted to work as an acceleration structures and on the other hand,
we examine particle acceleration by stimulated emission of radiation - a novel acceleration paradigm demonstrated
recently. Implications on future medical accelerators are discussed.
Two mirrors guiding light experience attractive or repulsive forces according to the eigenmode type of symmetry,
but regardless of the specific details of the guiding structure. A transverse evanescent mode (TM or TE) that
has an anti-symmetric transverse field causes repulsion, while attraction occurs when the mode has a symmetric
transverse field. Transverse propagating modes, however, are always repulsive. One possible application for this
phenomenon is to use a symmetric mode supported, for instance, by two properly designed Bragg mirrors. By
varying the wavelength of the mode injected into the waveguide, it is possible to cross the light-line and switch
between attraction and repulsion. If the mirror is free to move in the transverse direction, then this is a scheme
for controlling its motion. Another possibility is to create a stable equilibrium with a superposition of transverse
evanescent symmetric and anti-symmetric modes. For this purpose, a more appealing configuration than Bragg
mirrors is a waveguide that consists of two dielectric slabs where the light is guided by total internal reflection.
Each slab is trapped in a potential well resulting in optical binding by eigenmodes.
Conference Committee Involvement (2)
Commercial and Biomedical Applications of Ultrafast Lasers IX
25 January 2009 | San Jose, California, United States
Commercial and Biomedical Applications of Ultrafast Lasers VIII
20 January 2008 | San Jose, California, United States
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