Mirrorless Lasing in Liquid Crystalline Photonic Bandgap Materials

2003 ◽  
Vol 776 ◽  
Author(s):  
Wenyi Cao ◽  
Antonio Muñoz ◽  
Peter Palffy-Muhoray ◽  
Bahman Taheri
Keyword(s):  
Population Inversion ◽  
Liquid Crystalline ◽  
Light Propagation ◽  
Photonic Bandgap ◽  
Photon Counting ◽  
Stimulated Emission ◽  
Photonic Bandgap Materials ◽  
Blue Phase ◽  
Counting Statistics ◽  
Applied Fields

AbstractLiquid crystals (LC) are promising photonic bandgap (PBG) materials. Certain LC phases have spatially modulated ground states and effectively form self-assembled PBG structures. These structures can also be made permanent by photopolymerization. Typically, LCs respond readily to applied fields, enabling modulation and switching of the bandgap. Since classical light propagation is forbidden, fluorescent emission in the band gap can lead to population inversion and stimulated emission at the band edges. Mirrorless lasing experiments provide an effective probe of the bandgap. We discuss the underlying physics, and present the results of mirrorless lasing in a variety of cholesteric LC materials, including recent results of photon counting statistics and 3-D lasing in the cholesteric blue phase.

Self-Assembly of Block Copolymers for Photonic-Bandgap Materials

MRS Bulletin ◽  
2005 ◽  
Vol 30 (10) ◽  
pp. 721-726 ◽  
Author(s):  
Jongseung Yoon ◽  
Wonmok Lee ◽  
Edwin L. Thomas
Keyword(s):  
Molecular Weight ◽  
Block Copolymer ◽  
Block Copolymers ◽  
Photonic Crystals ◽  
Liquid Crystalline ◽  
Photonic Bandgap ◽  
Photonic Bandgap Materials ◽  
Periodic Microstructures ◽  
Self Assembled ◽  
Bandgap Materials

AbstractSelf-assembled block copolymer systems with an appropriate molecular weight to produce a length scale that will interact with visible light are an alternative platform material for the fabrication of large-area, well-ordered photonic-bandgap structures at visible and near-IR frequencies.Over the past years, one-, two-, and three-dimensional photonic crystals have been demonstrated with various microdomain structures created through microphase separation of block copolymers. The size and shape of periodic microstructures of block copolymers can be readily tuned by molecular weight, relative composition of the copolymer, and blending with homopolymers or plasticizers.The versatility of photonic crystals based on block copolymers is further increased by incorporating inorganic nanoparticles or liquid-crystalline guest molecules (or using a liquid-crystalline block), or by selective etching of one of the microdomains and backfilling with high-refractive-index materials. This article presents an overview of photonic-bandgap materials enabled by self-assembled block copolymers and discusses the morphology and photonic properties of block-copolymer-based photonic crystals containing nanocomposite additives.We also provide a view of the direction of future research, especially toward novel photonic devices.

scholarly journals BLACK-BODY PHOTON CLUSTERING BY SEMICLASSICAL MEANS

2008 ◽  
Vol 23 (15) ◽  
pp. 1067-1077 ◽  
Author(s):  
J. P. LESTONE
Keyword(s):  
Quantum Theory ◽  
Photon Counting ◽  
Black Body ◽  
Stimulated Emission ◽  
Black Bodies ◽  
Counting Statistics ◽  
Photon Counting Statistics

If stimulated emission could be turned off, then only uncorrelated photons would be emitted from black bodies and the photon counting statistics would be Poissonian. Through the process of stimulated emission, some fraction of the photons emitted from a black body are correlated and thus emitted in clusters. This photon clustering can be calculated by semiclassical means. The corresponding results are in agreement with quantum theory.

Effect of the grain size on hysteresis of liquid-crystalline Blue Phase I

2012 ◽  
Vol 20 (6) ◽  
pp. 318 ◽  
Author(s):  
Prasenjit Nayek ◽  
Heon Jeong ◽  
Shin-Woong Kang ◽  
Seung Hee Lee ◽  
Heung-Shik Park ◽  
...  
Keyword(s):  
Grain Size ◽  
Phase I ◽  
Liquid Crystalline ◽  
Blue Phase

Thermal phase transition behaviours of the blue phase of bent-core nematogen and chiral dopant mixtures under different boundary conditions

Soft Matter ◽  
2014 ◽  
Vol 10 (41) ◽  
pp. 8224-8228 ◽  
Author(s):  
Min-Jun Gim ◽  
Gohyun Han ◽  
Suk-Won Choi ◽  
Dong Ki Yoon
Keyword(s):  
Phase Transition ◽  
Boundary Conditions ◽  
Liquid Crystalline ◽  
Isotropic Phase ◽  
Different Boundary Conditions ◽  
Various Boundary Conditions ◽  
Thermal Phase Transition ◽  
Thermal Phase ◽  
Blue Phase ◽  
Chiral Dopants

We have investigated dramatic changes in the thermal phase transition of a liquid-crystalline (LC) blue phase (BP) consisting of bent-core nematogen and chiral dopants under various boundary conditions during cooling from the isotropic phase.

Artificial versus natural crystals: effective wave impedance of printed photonic bandgap materials

2000 ◽  
Vol 48 (1) ◽  
pp. 95-106 ◽  
Author(s):  
C.A. Kyriazidou ◽  
H.E. Contopanagos ◽  
W.M. Merrill ◽  
N.G. Alexpoulos
Keyword(s):  
Photonic Bandgap ◽  
Wave Impedance ◽  
Photonic Bandgap Materials ◽  
Effective Wave ◽  
Bandgap Materials

scholarly journals Liquid-crystalline blue phase III and structures of broken icosahedral symmetry

1993 ◽  
Vol 48 (3) ◽  
pp. 2296-2299 ◽  
Author(s):  
Lech Longa ◽  
Werner Fink ◽  
Hans-Rainer Trebin
Keyword(s):  
Liquid Crystalline ◽  
Phase Iii ◽  
Icosahedral Symmetry ◽  
Blue Phase

Uniform Alignment of Liquid Crystalline Cubic Blue Phase II via Rubbing Treatment

2015 ◽  
Vol 611 (1) ◽  
pp. 186-191 ◽  
Author(s):  
Sunhwan Kim ◽  
Kibeom Kim ◽  
Seong-Yong Jo ◽  
Suk-Won Choi
Keyword(s):  
Phase Ii ◽  
Liquid Crystalline ◽  
Blue Phase

scholarly journals Optimization of Advanced Live-Cell Imaging through Red/Near-Infrared Dye Labeling and Fluorescence Lifetime-Based Strategies

2021 ◽  
Vol 22 (20) ◽  
pp. 11092
Author(s):  
Magalie Bénard ◽  
Damien Schapman ◽  
Christophe Chamot ◽  
Fatéméh Dubois ◽  
Guénaëlle Levallet ◽  
...  
Keyword(s):  
Fluorescence Lifetime ◽  
Live Cell Imaging ◽  
Near Infrared ◽  
Cell Imaging ◽  
Light Exposure ◽  
Photon Counting ◽  
Live Cell ◽  
Stimulated Emission ◽  
Plot Analysis ◽  
Phasor Plot

Fluorescence microscopy is essential for a detailed understanding of cellular processes; however, live-cell preservation during imaging is a matter of debate. In this study, we proposed a guide to optimize advanced light microscopy approaches by reducing light exposure through fluorescence lifetime (τ) exploitation of red/near-infrared dyes. Firstly, we characterized key instrumental elements which revealed that red/near-infrared laser lines with an 86x (Numerical Aperture (NA) = 1.2, water immersion) objective allowed high transmission of fluorescence signals, low irradiance and super-resolution. As a combination of two technologies, i.e., vacuum tubes (e.g., photomultiplier) and semiconductor microelectronics (e.g., avalanche photodiode), type S, X and R of hybrid detectors (HyD-S, HyD-X and HyD-R) were particularly adapted for red/near-infrared photon counting and τ separation. Secondly, we tested and compared lifetime-based imaging including coarse τ separation for confocal microscopy, fitting and phasor plot analysis for fluorescence lifetime microscopy (FLIM), and lifetimes weighting for enhanced stimulated emission depletion (STED) nanoscopy, in light of red/near-infrared multiplexing. Mainly, we showed that the choice of appropriate imaging approach may depend on fluorochrome number, together with their spectral/lifetime characteristics and STED compatibility. Photon-counting mode and sensitivity of HyDs together with phasor plot analysis of fluorescence lifetimes enabled the flexible and fast imaging of multi-labeled living H28 cells. Therefore, a combination of red/near-infrared dyes labeling with lifetime-based strategies offers new perspectives for live-cell imaging by enhancing sample preservation through acquisition time and light exposure reduction.

scholarly journals Photon counting statistics with imperfect detectors

2021 ◽  
Vol 2086 (1) ◽  
pp. 012096
Author(s):  
Aleksei Reutov ◽  
Denis Sych
Keyword(s):  
Continuous Wave ◽  
Single Photon ◽  
Functional Dependence ◽  
Photon Counting ◽  
Light Sources ◽  
Photon Detectors ◽  
Quantum Properties ◽  
Single Photon Detectors ◽  
The Mean ◽  
Counting Statistics

Abstract Measurement of photon statistics is an important tool for the verification of quantum properties of light. Due to the various imperfections of real single photon detectors, the observed statistics of photon counts deviates from the underlying statistics of photons. Here we analyze statistical properties of coherent states, and investigate a connection between Poissonian distribution of photons and sub-Poissonian distribution of photon counts due to the detector dead-time corrections. We derive a functional dependence between the mean number of photons and the mean number of photon counts, as well as connection between higher-order statistical moments, for the pulsed or continuous wave coherent light sources, and confirm the results by numerical simulations.

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