Cholesteric Structure-1 Optical Properties

Fergason, James L.

doi:10.1080/15421406608083274

Cited by 250 publications

(101 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The angular dependency of such scattering is shown in Figure 2b, where we report the experimentally measured reflectance peak (λ) as a function of the angle θ out . Such a dependence, in the case of low birefringence, can be described by Ferguson's equation [14,30] DOI: 10.1002/adom.201600451…”

mentioning

confidence: 99%

Biocompatible and Sustainable Optical Strain Sensors for Large‐Area Applications

Kamita

Frka‐Petesic

Allard

et al. 2016

Advanced Optical Materials

114

138

View full text Add to dashboard Cite

By a simple two-step procedure, large photonic strain sensors using a biocompatible cellulose derivative are fabricated. Transient color shifts of the sensors are explained by a theoretical model that consideres the deformation of cholesteric domains, which is in agreement with the experimental results. The extremely simple fabrication method is suitable for both miniaturization and large-sale manufacture, taking advantage of inexpensive and sustainable materials

show abstract

mentioning

confidence: 99%

Biocompatible and Sustainable Optical Strain Sensors for Large‐Area Applications

Kamita

Frka‐Petesic

Allard

et al. 2016

Advanced Optical Materials

114

138

View full text Add to dashboard Cite

show abstract

“…To conclude, the concept of hyperbolic SCMs was introduced in this communication. The hyperbolicity was found to significantly alter-but not eliminate-the exhibition of the circular Bragg phenomenon, which has long been known to be the distinctive signature of nonhyperbolic SCMs such as cholesteric liquid crystals 9 and chiral sculptured thin films. 6 Although practical realization of hyperbolic SCMs has yet to occur, physical vapor deposition offers suitable techniques to fabricate these materials.…”

Section: Numerical Results and Discussionmentioning

confidence: 97%

“…The stopband is best seen when the thickness of the SCM exceeds a certain number of helical pitches. 6,[9][10][11] When dissipation is small enough to be ignored, ̳ ε r ðzÞ is positive definite, and the variations of ε a;b;c with respect to the free-space wavelength λ 0 are also small enough to be ignored, the circular-polarization-sensitive stopband can be delineated as 4…”

Section: Introductionmentioning

confidence: 99%

Exhibition of circular Bragg phenomenon by hyperbolic, dielectric, structurally chiral materials

Lakhtakia

2014

J. Nanophoton

View full text Add to dashboard Cite

Abstract. The relative permittivity dyadic of a dielectric structurally chiral material (SCM) varies helicoidally along a fixed direction; in consequence, the SCM exhibits the circular Bragg phenomenon, which is the circular-polarization-selective reflection of light. The introduction of hyperbolicity in an SCM-by making either one or two but not all three eigenvalues of the relative permittivity dyadic acquire negative real parts-does not eliminate the circular Bragg phenomenon, but significantly alters the regime for its exhibition. Significantly wider circularpolarization-sensitive stopbands may be exhibited by hyperbolic SCMs in comparison to nonhyperbolic SCMs. Physical vapor deposition techniques appear to be suitable to fabricate hyperbolic SCMs. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

show abstract

“…Figure 1). Fergason [11] Table 1. It should be emphasized that the quotient of the SR wavelengths for normal (ÄR) and oblique incidence (Äjf) is the same in the BP I and BP II as well as in the cholesteric phase indicating clearly that the three polymorphic states obey the same Bragg-like reflection law.…”

Section: Dedicated To Prof Dr E Kuss On the Occasion Of His 65th Bimentioning

confidence: 99%

Evidence for Polymorphism within the So-called "Blue Phase" of Cholesteric Esters. IV. Temperature and Angular Dependence of Selective Reflection

Bergmann¹,

Stegemeyer²

1979

Zeitschrift Für Naturforschung A

View full text Add to dashboard Cite

From selective reflection (SR) measurements as a function of temperature it has been shown that cholesteryl myristate exhibits two "blue phases" (BP) between the isotropic and the cholesteric state. The SR of the two BP shows the same angular dependence as found in the corresponding cholesteric state. From our results a model of the BP is proposed with the molecular axes inclined to the helix axis by a critical angle of 54.74° explaining the absence of birefringence as well as the cholesteric-like optical properties.Recently, it has been shown by optical and calorimetric measurements that the phenomenon of the so-called "blue phase" (BP) of various cholesteryl esters is caused by one or even two thermodynamically stable phases just below the clearing points [1,2].The characteristic colours of BP leading to their trivial name [3] originate from selective reflection (SR) of circularly polarized light accompanied by an anomalous dispersion of optical rotatory power (ORD) [4] with the same sign as that in the cholesteric state: left handed for cholesteryl myristate (CM) and nonanoate (CN), right handed for cholesteryl chloride [5]. This optical behaviour indicates a helical arrangement of molecules within the BP similar to the normal cholesteric phase, but on the other hand no birefringence has been detected [4,6]. An obvious explanation of the optical isotropy due to a globular structure of randomly oriented helical axes seems to be not compatible with the small half-width of the SR-bands of about 10 nm found in all BP [2]. Please order a reprint rather than making your own copy.In a former paper Goldberg and Schnur [7] mentioned the colour of light reflection in BP not to be dependent on the observation angle in contrast to the behaviour of the cholesteric phase [8]. As this observation is not consistent with our SR results the angular dependence of BP emission has been reinvestigated. By a simple experiment it could be shown easily that the SR of BP actually does depend on the observation angle: Cooling down CN in a thermostatted capillary tube close below the clearing point (91.5 °C) a bright green colour appears if the sampel is illuminated with white light in the viewing direction whereas the colour changes to blue with an angle of 90° between the direction of incidence and observation.Quantitative information about the angle dependence has been obtained by measuring the spectral distribution of SR by means of a fluorescence spectrophotometer MPF 4 (Perkin-Elmer). Synchronous scanning of the excitation and emission monochromator enables SR measurements for oblique light incidence. Because of the beam geometry given by the construction of the MPF 4 photometer the sum of the angles of incidence, (pi, and observation, q?s, always is 90°. § = 21° (see Figure 1). The aperture at the entrance slits of both monochromators was reduced to 1°. The temperature was controlled to a stability better than 0.05 °C. The s...

show abstract

Cholesteric Structure-1 Optical Properties

Cited by 250 publications

References 2 publications

Biocompatible and Sustainable Optical Strain Sensors for Large‐Area Applications

Biocompatible and Sustainable Optical Strain Sensors for Large‐Area Applications

Exhibition of circular Bragg phenomenon by hyperbolic, dielectric, structurally chiral materials

Evidence for Polymorphism within the So-called "Blue Phase" of Cholesteric Esters. IV. Temperature and Angular Dependence of Selective Reflection

Contact Info

Product

Resources

About