Optical axis gratings

Optical axis gratings

Optical axis gratings (OAGs) are gratings of optical axis of a birefringent material. In OAGs, the birefringence of the material is constant, while the direction of optical axis is periodically modulated in a fixed direction. In this way they are different from the regular phase gratings, in which the refractive index is modulated and the direction of the optical axis is constant.

The optical axis in OAGs can be modulated in either transverse or the longitudinal direction, which causes it to act as a diffractive or a reflective component. Numerous modulation profiles allow variation in the optical properties of the OAGs.

Examples of OAGs

An example of a transverse OAG, the so-called cycloidal OAG, is shown in Fig. 1. The optical axis in this grating is monotonously modulated in transverse direction. This grating is capable of diffracting "all" incident light into either +1st or −1st order in a micrometer-thick layer cite journal
author = H. Sarkissian, S.V. Serak, N.V. Tabiryan, L.B. Glebov, V. Rotar, B.Ya. Zeldovich
year = 2006
month = August
title = Polarization-controlled switching between diffraction orders in transverse-periodically aligned nematic liquid crystals
journal = Optics Letters
volume = 31
issue = 15
pages = 2248–2250
url = http://ol.osa.org/abstract.cfm?id=90803
doi = 10.1364/OL.31.002248
] cite journal
author = H. Sarkissian, N. Tabiryan, B. Park, B. Zeldovich
year = 2006
title = Periodically Aligned Liquid Crystal: Potential application for projection displays
journal = Molecular Crystals and Liquid Crystals
volume = 451
pages = 1–19
doi = 10.1080/154214090959957
] . The cycloidal OAGs have already been proven to be very efficient in beam steering and optical switching. ]

In another type of OAG, the optical axis is modulated in the direction of light propagation (Fig. 2) with a modulation period equal to a fraction of the wavelength (200-3000 nm)cite journal
author = H. Sarkissian, N. Tabiryan, B. Zeldovich
title = Polarization-universal bandgap in periodically twisted nematics
journal = Optics Letters
volume = 31
issue = 11
pages = 1678–1680
url = http://ol.osa.org/abstract.cfm?id=89809
doi = 10.1364/OL.31.001678
year = 2006
] cite journal
author = H. Sarkissian, B. Zeldovich, N. Tabiryan
title = Longitudinally modulated bandgap nematic structure
year = 2006
uri = http://josab.osa.org/abstract.cfm?id=95673
volume = 23
pages = 1712–1717
] . This modulation prevents these frequencies from propagating within the grating, acting as a band-stop filter. As a result, any light with frequency within the matching range will be reflected from the OAG. However, unlike cholesterics which reflect only one of two circular polarizations of incident light, this OAG reflects any polarization ] ] .


Optical axis gratings can be implemented in various materials, including liquid crystals, polymers, birefringent crystals, magnetic crystals and subwavelength gratings. This new type of grating has broad potential in imaging, liquid crystal display, communication, and numerous military applications.


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Optical axis grating — Optical axis gratings (OAGs) are gratings of optical axis of a birefringent material. In OAGs, the birefringence of the material is constant, while the direction of optical axis is periodically modulated in a fixed direction. In this way they are …   Wikipedia

  • Optical cavity — An optical cavity or optical resonator is an arrangement of mirrors that forms a standing wave cavity resonator for light waves. Optical cavities are a major component of lasers, surrounding the gain medium and providing feedback of the laser… …   Wikipedia

  • Optical lattice — Simulation of an optical lattice potential. An optical lattice is formed by the interference of counter propagating laser beams, creating a spatially periodic polarization pattern. The resulting periodic potential may trap neutral atoms via the… …   Wikipedia

  • List of optical topics — Probably some Wikipedia articles on topics in optics are not yet listed on this page. If you cannot find the topic you are interested in on this page, the article may nonetheless exist; you can try to find it using the Search box, or look in and… …   Wikipedia

  • Diffraction grating — A very large reflecting diffraction grating. In optics, a diffraction grating is an optical component with a periodic structure, which splits and diffracts light into several beams travelling in different directions. The directions of these beams …   Wikipedia

  • Birefringence — Displacement of light rays with perpendicular polarization through a birefringent material …   Wikipedia

  • Index of optics articles — Optics is the branch of physics which involves the behavior and properties of light, including its interactions with matter and the construction of instruments that use or detect it.[1] Optics usually describes the behavior of visible,… …   Wikipedia

  • OAG (disambiguation) — OAG may refer to: OAG (band) Malaysian rock band Official Airline Guide Office of the Advocate General for Scotland Optical axis gratings Orange Airport (IATA code) Officine Automobilistiche Grugliasco brand of FIAT This disambiguation page list …   Wikipedia

  • Fiber Bragg grating — A fiber Bragg grating (FBG) is a type of distributed Bragg reflector constructed in a short segment of optical fiber that reflects particular wavelengths of light and transmits all others. This is achieved by adding a periodic variation to the… …   Wikipedia

  • optics — /op tiks/, n. (used with a sing. v.) the branch of physical science that deals with the properties and phenomena of both visible and invisible light and with vision. [1605 15; < ML optica < Gk optiká, n. use of neut. pl. of OPTIKÓS; see OPTIC,… …   Universalium

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.