43 research outputs found
Quantum Goos-H\"{a}nchen shift and tunneling transmission at a curved step potential
We study the quantum Goos-H\"{a}nchen (GH) shift and the tunneling
transmission at a curved step potential by investigating the time evolution of
a wave packet. An initial wave packet is expanded in terms of the eigenmodes of
a circular step potential. Its time evolution is then given by the interference
of their simple eigenmode oscillations. We show that the GH shift along the
step boundary can be explained by the energy-dependent phase loss upon
reflection, which is defined by modifying the one-dimensional (1D) effective
potential derived from the 2D circular system. We also demonstrate that the
tunneling transmission of the wave packet is characterized by a free-space
image distant from the boundary. The tunneling transmission exhibits a rather
wide angle divergence and the direction of maximum tunneling is slightly
rotated from the tangent at the incident point, which is consistent with the
time delay of the tunneling wave packet computed in the 1D modified effective
potential
Synchronization of Chaotic Oscillators due to Common Delay Time Modulation
We have found a synchronization behavior between two identical chaotic
systems^M when their delay times are modulated by a common irregular signal. ^M
This phenomenon is demonstrated both in two identical chaotic maps whose
delay times are driven by a common^M chaotic or random signal and in two
identical chaotic oscillators whose delay times are driven by^M a signal of
another chaotic oscillator. We analyze the phenomenon by using^M the Lyapunov
exponents and discuss it in relation with generalized synchronization.^MComment: 5 pages, 4 figures (to be published in PRE
Boundary integral equation method for resonances in gradient index cavities designed by conformal transformation optics
In the case of two-dimensional gradient index cavities designed by the
conformal transformation optics, we propose a boundary integral equation method
for the calculation of resonant mode functions by employing a fictitious space
which is reciprocally equivalent to the physical space. Using the Green's
function of the interior region of the uniform index cavity in the fictitious
space, resonant mode functions and their far-field distributions in the
physical space can be obtained. As a verification, resonant modes in
lima\c{c}on-shaped transformation cavities were calculated and mode patterns
and far-field intensity distributions were compared with those of the same
modes obtained from the finite element method.Comment: 13 pages, 6 figure
Dependence of far-field characteristics on the number of lasing modes in stadium-shaped InGaAsP microlasers
We study spectral and far-field characteristics of lasing emission from
stadium-shaped semiconductor (InGaAsP) microlasers. We demonstrate that the
correspondence between a lasing far-field emission pattern and the result of a
ray simulation becomes better as the number of lasing modes increases. This
phenomenon is reproduced in the wave calculation of the cavity modes.Comment: 7 pages, 3 figure
Ultrathin, polarization-independent, and focus-tunable liquid crystal diffractive lens for augmented reality
Despite the recent advances in augmented reality (AR), which has shown the
potential to significantly impact on our daily lives by offering a new way to
manipulate and interact with virtual information, minimizing visual discomfort
due to the vergence-accommodation conflict remains a challenge. Emerging AR
technologies often exploit focus-tunable optics to address this problem.
Although they demonstrated improved depth perception by enabling proper focus
cues, a bulky form factor of focus-tunable optics prevents their use in the
form of a pair of eyeglasses. Herein, we describe an ultrathin, focus-tunable
liquid crystal (LC) diffractive lens with a large aperture, a low weight, and a
low operating voltage. In addition, we show that the polarization dependence of
the lens, which is an inherent optical property of LC lenses, can be eliminated
using birefringent thin films as substrates and by aligning the optical axes of
the birefringent substrates and LC at a specific angle. The polarization
independence eliminates the need for a polarizer, thus further reducing the
form factor of the optical system. Next, we demonstrate a prototype of AR
glasses with addressable focal planes using the ultrathin lens. The prototype
AR glasses can adjust the accommodation distance of the virtual image,
mitigating the vergence-accommodation conflict without substantially
compromising the form factor or image quality. This research on ultrathin lens
technology shows promising potential for developing compact optical displays in
various applications.Comment: 23 pages, 9 figure