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In optics, polarized light can be described using the Jones calculus, discovered by R. C. Jones in 1941. Polarized light is represented by a Jones vector, and linear optical elements are represented by Jones matrices. When light crosses an optical element the resulting polarization of the emerging light is found by taking the product of the Jones matrix of the optical element and the Jones vector of the incident light. Note that Jones calculus is only applicable to light that is already fully polarized. Light which is randomly polarized, partially polarized, or incoherent must be treated using Mueller calculus.
Liquid crystals (LCs) are a state of matter which has properties between those of conventional liquids and those of solid crystals. For instance, a liquid crystal may flow like a liquid, but its molecules may be oriented in a crystal-like way. There are many different types of liquid-crystal phases, which can be distinguished by their different optical properties. The contrasting areas in the textures correspond to domains where the liquid-crystal molecules are oriented in different directions. Within a domain, however, the molecules are well ordered. LC materials may not always be in a liquid-crystal state of matter.
Nonlinear optics (NLO) is the branch of optics that describes the behaviour of light in nonlinear media, that is, media in which the polarization density P responds non-linearly to the electric field E of the light. The non-linearity is typically observed only at very high light intensities (values of atomic electric fields, typically 108 V/m) such as those provided by lasers. Above the Schwinger limit, the vacuum itself is expected to become nonlinear. In nonlinear optics, the superposition principle no longer holds.
In optics, a diffraction grating is an optical component with a periodic structure that splits and diffracts light into several beams travelling in different directions. The emerging coloration is a form of structural coloration. The directions of these beams depend on the spacing of the grating and the wavelength of the light so that the grating acts as the dispersive element. Because of this, gratings are commonly used in monochromators and spectrometers.
An optical isolator, or optical diode, is an optical component which allows the transmission of light in only one direction. It is typically used to prevent unwanted feedback into an optical oscillator, such as a laser cavity.
Birefringence is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light. These optically anisotropic materials are said to be birefringent. The birefringence is often quantified as the maximum difference between refractive indices exhibited by the material. Crystals with non-cubic crystal structures are often birefringent, as are plastics under mechanical stress.
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. Optics usually describes the behavior of visible, ultraviolet, and infrared light. Because light is an electromagnetic wave, other forms of electromagnetic radiation such as X-rays, microwaves, and radio waves exhibit similar properties.
An acousto-optic modulator (AOM), also called a Bragg cell or an acousto-optic deflector (AOD), uses the acousto-optic effect to diffract and shift the frequency of light using sound waves. They are used in lasers for Q-switching, telecommunications for signal modulation, and in spectroscopy for frequency control. A piezoelectric transducer is attached to a material such as glass. An oscillating electric signal drives the transducer to vibrate, which creates sound waves in the material. These can be thought of as moving periodic planes of expansion and compression that change the index of refraction. Incoming light scatters off the resulting periodic index modulation and interference occurs similar to Bragg diffraction. The interaction can be thought of as a three-wave mixing process resulting in Sum-frequency generation or Difference-frequency generation between phonons and photons.
An optical vortex is a zero of an optical field; a point of zero intensity. The term is also used to describe a beam of light that has such a zero in it. The study of these phenomena is known as singular optics.
A fiber laser is a laser in which the active gain medium is an optical fiber doped with rare-earth elements such as erbium, ytterbium, neodymium, dysprosium, praseodymium, thulium and holmium. They are related to doped fiber amplifiers, which provide light amplification without lasing. Fiber nonlinearities, such as stimulated Raman scattering or four-wave mixing can also provide gain and thus serve as gain media for a fiber laser.
Digital holography refers to the acquisition and processing of holograms with a digital sensor array , typically a CCD camera or a similar device. Image rendering, or reconstruction of object data is performed numerically from digitized interferograms. Digital holography offers a means of measuring optical phase data and typically delivers three-dimensional surface or optical thickness images. Several recording and processing schemes have been developed to assess optical wave characteristics such as amplitude, phase, and polarization state, which make digital holography a very powerful method for metrology applications .
Acousto-optics is a branch of physics that studies the interactions between sound waves and light waves, especially the diffraction of laser light by ultrasound through an ultrasonic grating.
Photothermal spectroscopy is a group of high sensitivity spectroscopy techniques used to measure optical absorption and thermal characteristics of a sample. The basis of photothermal spectroscopy is the change in thermal state of the sample resulting from the absorption of radiation. Light absorbed and not lost by emission results in heating. The heat raises temperature thereby influencing the thermodynamic properties of the sample or of a suitable material adjacent to it. Measurement of the temperature, pressure, or density changes that occur due to optical absorption are ultimately the basis for the photothermal spectroscopic measurements.
There are various classifications of the electro-optical modes of liquid crystal displays (LCDs).
In optics, a nematicon is a spatial soliton in nematic liquid crystals (NLC). The name was invented in 2003 by G. Assanto. and used thereafter Nematicons are generated by a special type of optical nonlinearity present in NLC: the light induced reorientation of the molecular director. This nonlinearity arises from the fact that the molecular director tends to align along the electric field of light. Nematicons are easy to generate because the NLC dielectric medium exhibits the following properties:
A liquid-crystal laser is a laser that uses a liquid crystal as the resonator cavity, allowing selection of emission wavelength and polarization from the active laser medium. The lasing medium is usually a dye doped into the liquid crystal. Liquid-crystal lasers are comparable in size to diode lasers, but provide the continuous wide spectrum tunability of dye lasers while maintaining a large coherence area. The tuning range is typically several tens of nanometers. Self-organization at micrometer scales reduces manufacturing complexity compared to using layered photonic metamaterials. Operation may be either in continuous wave mode or in pulsed mode.
The angular momentum of light is a vector quantity that expresses the amount of dynamical rotation present in the electromagnetic field of the light. While traveling approximately in a straight line, a beam of light can also be rotating around its own axis. This rotation, while not visible to the naked eye, can be revealed by the interaction of the light beam with matter.
An acousto-optic programmable dispersive filter (AOPDF) is a special type of collinear-beam acousto-optic modulator capable of shaping spectral phase and amplitude of ultrashort laser pulses. AOPDF was invented by Pierre Tournois. Typically, quartz crystals are used for the fabrication of the AOPDFs operating in the UV spectral domain, paratellurite crystals are used in the visible and the NIR and calomel in the MIR (3-20 µm). Recently introduced Lithium niobate crystals allow for high-repetition rate operation owing to their high acoustic velocity. The AOPDF is also used for the active control of the carrier-envelope phase of the few-cycle optical pulses and as a part of pulse-measurement schemes. Although sharing a lot in principle of operation with an acousto-optic tunable filter, the AOPDF should not be confused with it, since in the former the tunable parameter is the transfer function and in the latter it is the impulse response
The term plane of polarization refers to the direction of polarization of linearly-polarized light or other electromagnetic radiation. Unfortunately the term is used with two contradictory meanings. As originally defined by Étienne-Louis Malus in 1811, the plane of polarization coincided with the plane containing the direction of propagation and the magnetic vector. In modern literature, the term plane of polarization, if it is used at all, is likely to mean the plane containing the direction of propagation and the electric vector, because the electric field has the greater propensity to interact with matter.
A virtually imaged phased array (VIPA) is an angular dispersive device that, like a prism or a diffraction grating, splits light into its spectral components. It works almost independently of polarization. In contrast to prisms or regular diffraction gratings, it has a much higher angular dispersion but has a smaller free spectral range. This aspect is similar to that of an Echelle grating which is usually used in reflection, since high diffraction orders are also used there. The VIPA can be a compact optical component with high wavelength resolving power.
References
- 1 2 H. Sarkissian; S.V. Serak; N.V. Tabiryan; L.B. Glebov; V. Rotar; B.Ya. Zeldovich (August 2006). "Polarization-controlled switching between diffraction orders in transverse-periodically aligned nematic liquid crystals". Optics Letters. 31 (15): 2248–2250. Bibcode:2006OptL...31.2248S. doi:10.1364/OL.31.002248. PMID 16832448.
- ↑ H. Sarkissian; N. Tabiryan; B. Park; B. Zeldovich (2006). "Periodically Aligned Liquid Crystal: Potential application for projection displays". Molecular Crystals and Liquid Crystals. 451: 1–19. arXiv: cond-mat/0508555 . doi:10.1080/154214090959957. S2CID 96404563.
- 1 2 H. Sarkissian; N. Tabiryan; B. Zeldovich (2006). "Polarization-universal bandgap in periodically twisted nematics". Optics Letters. 31 (11): 1678–1680. Bibcode:2006OptL...31.1678S. doi:10.1364/OL.31.001678. PMID 16688259.
- 1 2 H. Sarkissian; B. Zeldovich; N. Tabiryan (2006). "Longitudinally modulated bandgap nematic structure". Journal of the Optical Society of America B. 23: 1712–1717. Bibcode:2006JOSAB..23.1712S. doi:10.1364/JOSAB.23.001712.