The circular Bragg phenomenon

Faryad, Muhammad; Lakhtakia, Akhlesh

doi:10.1364/aop.6.000225

Cited by 122 publications

(109 citation statements)

References 207 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…As a result, polarized light with the same handedness as that of the helically structured cholesteric liquid crystal diffracts (Figure 1), whereas the cross-handed circularly polarized wave travels virtually unaffected. This phenomenon is referred to as the selective reflection [1] or, alternatively, the Bragg circular diffraction for electromagnetic and acoustic waves [2]. The results obtained are readily generalized for any material with a helix-like response, including widely tunable heliconical structures [3].…”

Section: Introductionmentioning

confidence: 92%

“…These defect modes are localized optical states normally corresponding to the whole numbers of halfwaves accommodated in the cavity. There are a number of distinctive polarization features [5][6][7][8][9][10][11] associated with the chiral defect applications [2,[12][13][14][15], among which the twist defect, lacking an intermediate layer and having zero thickness, is most prominent [16,17]. Strict theoretical [4,[18][19][20] and experimental [16,21,22] studies of the phenomenon gave rise to a discussion on polarization and relaxation time of the localized state [23,24].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Chiral Optical Tamm States: Temporal Coupled-Mode Theory

et al. 2017

View full text Add to dashboard Cite

Abstract:The chiral optical Tamm state (COTS) is a special localized state at the interface of a handedness-preserving mirror and a structurally chiral medium such as a cholesteric liquid crystal or a chiral sculptured thin film. The spectral behavior of COTS, observed as reflection resonances, is described by the temporal coupled-mode theory. Mode coupling is different for two circular light polarizations because COTS has a helical structure replicating that of the cholesteric. The mode coupling for co-handed circularly polarized light exponentially attenuates with the cholesteric layer thickness since the COTS frequency falls into the stop band. Cross-handed circularly polarized light freely goes through the cholesteric layer and can excite COTS when reflected from the handedness-preserving mirror. The coupling in this case is proportional to anisotropy of the cholesteric and theoretically only anisotropy in magnetic permittivity can ultimately cancel this coupling. These two couplings being equal result in a polarization crossover (the Kopp-Genack effect) for which a linear polarization is optimal to excite COTS. The corresponding cholesteric thickness and scattering matrix for COTS are generally described by simple expressions.

show abstract

Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Chiral Optical Tamm States: Temporal Coupled-Mode Theory

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Of most interest are cases where light of a given circular polarization has a slightly different response when applied to a left-handed chiral molecule relative to a right-handed one -leading to the possibility of enantiomer separation. In the microscale, such optomechanical separation has been achieved experimentally, 24 although difficulties arise on downscaling to molecular levels: for example, suggestions based on circular Bragg reflection 25 prove problematic due to thermal effects.…”

Section: Discussionmentioning

confidence: 99%

On the viability of achieving chiral separation through the optical manipulation of molecules

Andrews

2015

Complex Light and Optical Forces IX

View full text Add to dashboard Cite

Several different optical methods have recently been proposed for the potential separation of chiral molecules according to their intrinsic handedness. Applying fundamental symmetry and electrodynamical principles provides a perspective that casts doubt over the viability of some of the more extravagant claims. However there is a genuine basis for achieving chiral separation by using circularly polarized light to deliver chirally sensitive optical forces. The mechanism comes into play when molecules (or nanoscale particles) are optically trapped in a laser beam by forward Rayleigh scattering, as a result of trapping forces that depend on positioning within the beam profile. In such a setup, chiral molecules experience subtle additional forces associated with a combination of electric and magnetic transition dipoles; when circularly polarized light is used for the trapping, a discriminatory response can be identified that has the capacity to separate left-and righthanded molecular isomers. Here, clear differences can be observed between the behavior of isotropic liquids and poled solutions or liquid crystals. Detailed analysis provides an objective basis to assess new prospects for the recognition and differentiation of molecules with opposite chiral form, identifying and paving the way for future commercial applications.

show abstract

“…The almost total reflection of CPL of one handedness, while very limited for the other one, is frequently referred to as the circular Bragg phenomenon. [70] This phenomenon is usually observed in periodically nonhomogeneous materials, such as cholesteric liquid crystal or sculptured thin films [68] (which will be discussed in more details in the next section).…”

Section: Models For Dielectric Micro/nano Helicesmentioning

confidence: 95%

Materials and 3D Designs of Helix Nanostructures for Chirality at Optical Frequencies

Passaseo

Esposito

Cuscunà

et al. 2017

Advanced Optical Materials

View full text Add to dashboard Cite

The capability to fully control the chiro‐optical properties of metamaterials has drawn considerable attention due to developments in metamaterial fabrication techniques and a deeper understanding of the light–matter interaction, enabling a number of applications from integrated photonics to life sciences. From simple geometrical studies on single helix shaped metamaterials, both the design complexity and nanofabrication capability are steadily increasing allowing to extend their properties to the visible regime and beyond. In this work, helix‐shaped micro‐ and nanostructures are reviewed, which have the possibility to modulate their optical response in the linear regime at optical frequencies by spatial arrangement or by constitutive material. An overview of different theories describing the general optical operation of chiral media and a discussion on experimental results obtained by the state‐of‐the‐art helix structures realized by different fabrication techniques is provided. Finally, advanced designs for improved functionality envisaged to match practical applications or to enable new optical multifunctionalities are compared. Even if many applications have been envisaged only theoretically, the continuous effort and progress shown by the research community engaged in this field suggests that helical chiral metamaterials could represent a disruptive breakthrough for advanced optical devices.

show abstract

The circular Bragg phenomenon

Cited by 122 publications

References 207 publications

Chiral Optical Tamm States: Temporal Coupled-Mode Theory

Chiral Optical Tamm States: Temporal Coupled-Mode Theory

On the viability of achieving chiral separation through the optical manipulation of molecules

Materials and 3D Designs of Helix Nanostructures for Chirality at Optical Frequencies

Contact Info

Product

Resources

About