The circular Bragg phenomenon

Muhammad Faryad, Akhlesh Lakhtakia

Research output: Contribution to journalArticlepeer-review

115 Scopus citations


Exhibited by structurally chiral materials-such as Reusch piles, cholesteric liquid crystals (CLCs), and chiral sculptured thin films (STFs)-due to their helical nonhomogeneity along a fixed axis, the circular Bragg phenomenon is the almost total reflection of the incident light of the co-handed circularpolarization state but very little reflection of the incident light of the crosshanded circular-polarization state. Manifesting itself in spectral regimes that depend on the angle of incidence, the structural period, and the relative permittivity dyadic, the phenomenon amounts to the formation of a light pipe that bleeds energy backward under appropriate conditions. Mild dissipation and dispersion do not significantly affect the circular Bragg regime. Every structurally chiral material of sufficient thickness is essentially a circularpolarization- sensitive band-rejection filter. Cascades of these materials with or without structural defects can be used to satisfy complex filtering requirements, such as multiband, narrowband, and ultra-narrowband filtering. A shift in the circular Bragg regime due to infiltration of a chiral STF by a fluid enables optical sensing. Sources of circularly polarized light can be fabricated by embedding emission sources in CLCs and chiral STFs.

Original languageEnglish (US)
Pages (from-to)225-292
Number of pages68
JournalAdvances in Optics and Photonics
Issue number2
StatePublished - Jun 30 2014

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics


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