scholarly journals Highly Chiral Exceptional Point in Perturbed Coupled Resonators

2021 ◽  
Vol 2015 (1) ◽  
pp. 012122
Author(s):  
S. Ramezanpour ◽  
Y. Ra’di ◽  
A. Alù ◽  
A. Bogdanov
Keyword(s):  
Optical System ◽  
Light Propagation ◽  
Exceptional Point ◽  
Laser Mode ◽  
Coupled Resonators ◽  
Mode Selectivity

Abstract Exceptional point (EP) is a non-Hermitian spectral degeneracy that has application in ultrasensitive sensors and laser mode selectivity. By employing strong chirality in an optical system, the direction of light propagation can be controlled and subwavelength particles can be detected. Here, we show that EP with high chirality can appear in the coupled resonators perturbed by a scatterer, in which both the distance and position of the scatterer can be tuned. We achieve strong chiral EP in two different distances between the resonators, with chirality around 0.99 in both cases.

Soliton-Like Light Propagation through Coupled Resonators Constructed with Periodic Metal-Dielectric Layers

2013 ◽  
Vol 339 ◽  
pp. 706-713
Author(s):  
Yu Guang Zhu ◽  
Yun Tuan Fang ◽  
Wei Li Hu ◽  
Wei Zhong Yan
Keyword(s):  
Group Velocity ◽  
Free Space ◽  
Light Propagation ◽  
Tight Binding ◽  
Coupled Resonators ◽  
Light Velocity ◽  
One Dimensional ◽  
Resonator Structure ◽  
Transmission Mechanisms ◽  
Dielectric Layers

in order to obtain a soliton-like light propagation, we design a coupled resonator structure constructed with one-dimensional periodic metal-dielectric layers. Through tight-binding analysis and the Blochs theorem, we study its transmission mechanisms. Basing on the transmission mechanisms, we achieve a soliton-like light propagation in it with a group velocity being smaller light velocity in free space.

scholarly journals A Simplified Model for Optical Systems with Random Phase Screens

Sensors ◽  
2021 ◽  
Vol 21 (17) ◽  
pp. 5811
Author(s):  
Malchiel Haskel ◽  
Adrian Stern
Keyword(s):  
Optical System ◽  
Light Propagation ◽  
Random Phase ◽  
Biological Tissues ◽  
Complete Separation ◽  
Optical Systems ◽  
Scattering Media ◽  
The Individual ◽  
Phase Screens ◽  
Si Effect

A first-order optical system with arbitrary multiple masks placed at arbitrary positions is the basic scheme of various optical systems. Generally, masks in optical systems have a non-shift invariant (SI) effect; thus, the individual effect of each mask on the output cannot be entirely separated. The goal of this paper is to develop a technique where complete separation might be achieved in the common case of random phase screens (RPSs) as masks. RPSs are commonly used to model light propagation through the atmosphere or through biological tissues. We demonstrate the utility of the technique on an optical system with multiple RPSs that model random scattering media.

Optical Propagation in Linear Media

2006 ◽  
Author(s):  
Michael E. Thomas
Keyword(s):  
Solid State ◽  
Optical System ◽  
Light Propagation ◽  
Laser Light ◽  
Reference Book ◽  
Optical Energy ◽  
Optical Propagation ◽  
Theory And Experiment

A typical optical system is composed of three basic components: a source, a detector, and a medium in which the optical energy propagates. Many textbooks cover sources and detectors, but very few cover propagation in a comprehensive way, incorporating the latest progress in theory and experiment concerning the propagating medium. This book fulfills that need. It is the first comprehensive and self-contained book on this topic. It is useful reference book for researchers, and a textbook for courses like Laser Light Propagation, Solid State Optics, and Optical Propagation in the Atmosphere.

scholarly journals An energy conservative hp-scheme for light propagation using Liouville’s equation for geometrical optics

2020 ◽  
Vol 238 ◽  
pp. 02005
Author(s):  
Robert A.M. van Gestel ◽  
Martijn J.H. Anthonissen ◽  
Jan H.M. ten Thije Boonkkamp ◽  
Wilbert L. IJzerman
Keyword(s):  
Optical System ◽  
Light Propagation ◽  
Energy Propagation ◽  
Conservation Of Energy ◽  
Adaptive Scheme ◽  
Propagation Of Light ◽  
Light Rays ◽  
Liouville’S Equation ◽  
Full Domain ◽  
Space Description

In this contribution an alternative method to standard forward ray-tracing is briefly outlined. The method is based on a phase-space description of light propagating through an optical system. The propagation of light rays are governed by Hamilton’s equations. Conservation of energy and étendue for a beam of light, allow us to derive a Liouville’s equation for the energy propagation through an optical system. Liouville’s equation is solved numerically using an hp-adaptive scheme, which for a smooth refractive index field is energy conservative. A proper treatment of optical interfaces ensures that the scheme is energy conservative over the full domain.

scholarly journals Chiral modes and directional lasing at exceptional points

2016 ◽  
Vol 113 (25) ◽  
pp. 6845-6850 ◽  
Author(s):  
Bo Peng ◽  
Şahin Kaya Özdemir ◽  
Matthias Liertzer ◽  
Weijian Chen ◽  
Johannes Kramer ◽  
...  
Keyword(s):  
Information Processing ◽  
Light Propagation ◽  
Laser Emission ◽  
Whispering Gallery Mode ◽  
Exceptional Point ◽  
Physical Systems ◽  
Whispering Gallery ◽  
On Chip ◽  
Resonator Modes ◽  
System Approaches

Controlling the emission and the flow of light in micro- and nanostructures is crucial for on-chip information processing. Here we show how to impose a strong chirality and a switchable direction of light propagation in an optical system by steering it to an exceptional point (EP)—a degeneracy universally occurring in all open physical systems when two eigenvalues and the corresponding eigenstates coalesce. In our experiments with a fiber-coupled whispering-gallery-mode (WGM) resonator, we dynamically control the chirality of resonator modes and the emission direction of a WGM microlaser in the vicinity of an EP: Away from the EPs, the resonator modes are nonchiral and laser emission is bidirectional. As the system approaches an EP, the modes become chiral and allow unidirectional emission such that by transiting from one EP to another one the direction of emission can be completely reversed. Our results exemplify a very counterintuitive feature of non-Hermitian physics that paves the way to chiral photonics on a chip.

scholarly journals Arbitrary order exceptional point induced by photonic spin–orbit interaction in coupled resonators

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Shubo Wang ◽  
Bo Hou ◽  
Weixin Lu ◽  
Yuntian Chen ◽  
Z. Q. Zhang ◽  
...  
Keyword(s):  
Arbitrary Order ◽  
Orbit Interaction ◽  
Exceptional Point ◽  
Spin Orbit ◽  
Coupled Resonators ◽  
Spin Orbit Interaction

scholarly journals Cascaded PT-Symmetric Artificial Sheets: Multimodal Manipulation of Self-Dual Emitter-Absorber Singularities, and Unidirectional and Bidirectional Reflectionless Transparencies

2021 ◽  
Author(s):  
Minye Yang ◽  
Zhilu Ye ◽  
Mohamed Farhat ◽  
Pai-Yen Chen
Keyword(s):  
Light Propagation ◽  
Propagation Direction ◽  
The Self ◽  
Exceptional Point ◽  
Frequency Selective Surfaces ◽  
Transmission Resonance ◽  
Loss Parameter ◽  
Transmission Resonances ◽  
Gain Loss ◽  
Dual Laser

Abstract We herein introduce cascaded parity-time (PT)-symmetric artificial sheets (e.g., metasurfaces or frequency selective surfaces) that may exhibit multiple higher-order laser-absorber modes and bidirectional reflectionless transmission resonances within the PT-broken phase, as well as a unidirectional reflectionless transmission resonance associated with the exceptional point (EP). We derive the explicit expressions of the gain-loss parameter required for obtaining these modes and their intriguing physical properties. By exploiting the cascaded PT structures, the gain-loss threshold for the self-dual laser-absorber operation can be remarkably lowered, while the EP remains unaltered. We further study interferometric sensing based on such a multimodal laser-absorber and demonstrate that its sensitivity could be unprecedentedly high and proportional to the number of metasurfaces along the light propagation direction.

A Field Emission System For Transmission Electron Microscopy

1973 ◽  
Vol 31 ◽  
pp. 298-299
Author(s):  
Michel Troyonal ◽  
Huei Pei Kuoal ◽  
Benjamin M. Siegelal
Keyword(s):  
Electron Microscope ◽  
Field Emission ◽  
Optical System ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Objective Lens ◽  
Electron Optical System ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Emission System

A field emission system for our experimental ultra high vacuum electron microscope has been designed, constructed and tested. The electron optical system is based on the prototype whose performance has already been reported. A cross-sectional schematic illustrating the field emission source, preaccelerator lens and accelerator is given in Fig. 1. This field emission system is designed to be used with an electron microscope operated at 100-150kV in the conventional transmission mode. The electron optical system used to control the imaging of the field emission beam on the specimen consists of a weak condenser lens and the pre-field of a strong objective lens. The pre-accelerator lens is an einzel lens and is operated together with the accelerator in the constant angular magnification mode (CAM).

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