Nonlinear photonic crystal

Last updated

Nonlinear photonic crystals are usually used as quasi-phase-matching materials. They can be one-dimensional, [1] two-dimensional [2] or three-dimensional. [3]

Contents

Nonlinear Photonic Crystals

Broadly speaking, nonlinear photonic crystals (PC) are periodic structures whose optical response depends on the intensity of the optical field that propagates into the crystal. An immediate consequence is that such structures have new optical properties with improved or new functionalities that cannot be obtained by using their linear counterpart, namely linear pPCs. One such example is optical tunability, that is, optical control of the response of devices based on PC. Although tunability of optical properties of photonic crystals can be achieved, for instance, by applying an electric field to an inverse opal PC infiltrated with nematic liquid crystal, by modulating the PC's index of refraction through the electro-optic effect induced by an external electric field, or through temperature-induced changes in the PC's index of refraction, high-speed operability desired for certain advanced optical communication systems can be obtained only if intrinsic optical nonlinearities in the PC material are employed. The reason for this is the ultra-fast response of certain nonlinear dielelectric materials to optical fields. In contrast to the now very extensive body of research in the properties and devices in linear photonic crystals, research into the theoretical and experimental behavior of these structures under conditions of intense optical fields, e.g. in the nonlinear regime, is still in its formative stages.

The index of refraction of a nonlinear crystal changes in response to an applied electromagnetic field. Some of the characteristics of nonlinear crystals used to generate entangled photons include:

  1. Nonlinearity: The refractive index of the crystal changes with the intensity of the incident light. This is known as the nonlinear optical response.
  2. Periodicity: The crystal has a regular, repeating structure. This is known as the lattice structure, which is responsible for the regular arrangement of the atoms in the crystal.
  3. Optical anisotropy: The crystal has different refractive indices along different crystallographic axes.
  4. Temperature and pressure sensitivity: The nonlinearity of the crystal can change with temperature and pressure, and thus the crystal should be kept in a stable temperature and pressure environment.
  5. High nonlinear coefficient: a large nonlinear coefficient is desirable, this allows generation a high number of entangled photons.
  6. High optical damage threshold: Crystal with high optical damage threshold can endure high intensity of the pumping beam.
  7. Transparency in the desired wavelength range: It is important for the crystal to be transparent in the wavelength range of the pump beam for efficient nonlinear interactions
  8. High optical quality and low absorption: The crystal should be high optical quality and low absorption to minimize loss of the pump beam and the generated entangled photons.

Related Research Articles

<span class="mw-page-title-main">Nonlinear optics</span> Branch of physics

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 (when the electric field of the light is >108 V/m and thus comparable to the atomic electric field of ~1011 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.

An electro–optic effect is a change in the optical properties of a material in response to an electric field that varies slowly compared with the frequency of light. The term encompasses a number of distinct phenomena, which can be subdivided into

<span class="mw-page-title-main">Photonic crystal</span> Periodic optical nanostructure that affects the motion of photons

A photonic crystal is an optical nanostructure in which the refractive index changes periodically. This affects the propagation of light in the same way that the structure of natural crystals gives rise to X-ray diffraction and that the atomic lattices of semiconductors affect their conductivity of electrons. Photonic crystals occur in nature in the form of structural coloration and animal reflectors, and, as artificially produced, promise to be useful in a range of applications.

<span class="mw-page-title-main">Metamaterial</span> Materials engineered to have properties that have not yet been found in nature

A metamaterial is any material engineered to have a property that is not found in naturally occurring materials. They are made from assemblies of multiple elements fashioned from composite materials such as metals and plastics. These materials are usually arranged in repeating patterns, at scales that are smaller than the wavelengths of the phenomena they influence. Metamaterials derive their properties not from the properties of the base materials, but from their newly designed structures. Their precise shape, geometry, size, orientation and arrangement gives them their smart properties capable of manipulating electromagnetic waves: by blocking, absorbing, enhancing, or bending waves, to achieve benefits that go beyond what is possible with conventional materials.

<span class="mw-page-title-main">Spontaneous parametric down-conversion</span> Optical process

Spontaneous parametric down-conversion is a nonlinear instant optical process that converts one photon of higher energy, into a pair of photons of lower energy, in accordance with the law of conservation of energy and law of conservation of momentum. It is an important process in quantum optics, for the generation of entangled photon pairs, and of single photons.

<span class="mw-page-title-main">Photodetector</span> Sensors of light or other electromagnetic energy

Photodetectors, also called photosensors, are sensors of light or other electromagnetic radiation. There is a wide variety of photodetectors which may be classified by mechanism of detection, such as photoelectric or photochemical effects, or by various performance metrics, such as spectral response. Semiconductor-based photodetectors typically photo detector have a p–n junction that converts light photons into current. The absorbed photons make electron–hole pairs in the depletion region. Photodiodes and photo transistors are a few examples of photo detectors. Solar cells convert some of the light energy absorbed into electrical energy.

Four-wave mixing (FWM) is an intermodulation phenomenon in nonlinear optics, whereby interactions between two or three wavelengths produce two or one new wavelengths. It is similar to the third-order intercept point in electrical systems. Four-wave mixing can be compared to the intermodulation distortion in standard electrical systems. It is a parametric nonlinear process, in that the energy of the incoming photons is conserved. FWM is a phase-sensitive process, in that the efficiency of the process is strongly affected by phase matching conditions.

<span class="mw-page-title-main">Optical parametric oscillator</span>

An optical parametric oscillator (OPO) is a parametric oscillator that oscillates at optical frequencies. It converts an input laser wave with frequency into two output waves of lower frequency by means of second-order nonlinear optical interaction. The sum of the output waves' frequencies is equal to the input wave frequency: . For historical reasons, the two output waves are called "signal" and "idler", where the output wave with higher frequency is the "signal". A special case is the degenerate OPO, when the output frequency is one-half the pump frequency, , which can result in half-harmonic generation when signal and idler have the same polarization.

<span class="mw-page-title-main">Fiber Bragg grating</span> Type of distributed Bragg reflector constructed in a short segment of optical fiber

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 creating a periodic variation in the refractive index of the fiber core, which generates a wavelength-specific dielectric mirror. Hence a fiber Bragg grating can be used as an inline optical fiber to block certain wavelengths, can be used for sensing applications, or it can be used as wavelength-specific reflector.

<span class="mw-page-title-main">Optical vortex</span> Optical phenomenon

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.

<span class="mw-page-title-main">3D optical data storage</span>

3D optical data storage is any form of optical data storage in which information can be recorded or read with three-dimensional resolution.

<span class="mw-page-title-main">Multiphoton lithography</span> Technique for creating microscopic structures

Multiphoton lithography of polymer templates has been known for years by the photonic crystal community. Similar to standard photolithography techniques, structuring is accomplished by illuminating negative-tone or positive-tone photoresists via light of a well-defined wavelength. The fundamental difference is, however, the avoidance of reticles. Instead, two-photon absorption is utilized to induce a dramatic change in the solubility of the resist for appropriate developers.

<span class="mw-page-title-main">Tunable metamaterial</span>

A tunable metamaterial is a metamaterial with a variable response to an incident electromagnetic wave. This includes remotely controlling how an incident electromagnetic wave interacts with a metamaterial. This translates into the capability to determine whether the EM wave is transmitted, reflected, or absorbed. In general, the lattice structure of the tunable metamaterial is adjustable in real time, making it possible to reconfigure a metamaterial device during operation. It encompasses developments beyond the bandwidth limitations in left-handed materials by constructing various types of metamaterials. The ongoing research in this domain includes electromagnetic materials that are very meta which mean good and has a band gap metamaterials (EBG), also known as photonic band gap (PBG), and negative refractive index material (NIM).

<span class="mw-page-title-main">Photonic metamaterial</span> Type of electromagnetic metamaterial

A photonic metamaterial (PM), also known as an optical metamaterial, is a type of electromagnetic metamaterial, that interacts with light, covering terahertz (THz), infrared (IR) or visible wavelengths. The materials employ a periodic, cellular structure.

A nonlinear metamaterial is an artificially constructed material that can exhibit properties not found in nature. Its response to electromagnetic radiation can be characterized by its permittivity and material permeability. The product of the permittivity and permeability results in the refractive index. Unlike natural materials, nonlinear metamaterials can produce a negative refractive index. These can also produce a more pronounced nonlinear response than naturally occurring materials.

A plasmonic metamaterial is a metamaterial that uses surface plasmons to achieve optical properties not seen in nature. Plasmons are produced from the interaction of light with metal-dielectric materials. Under specific conditions, the incident light couples with the surface plasmons to create self-sustaining, propagating electromagnetic waves known as surface plasmon polaritons (SPPs). Once launched, the SPPs ripple along the metal-dielectric interface. Compared with the incident light, the SPPs can be much shorter in wavelength.

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.

<span class="mw-page-title-main">Robert W. Boyd</span> American physicist

Robert William Boyd is an American physicist noted for his work in optical physics and especially in nonlinear optics. He is currently the Canada Excellence Research Chair Laureate in Quantum Nonlinear Optics based at the University of Ottawa, Professor of Physics cross-appointed to the School of Electrical Engineering and Computer Science at the University of Ottawa, and Professor of Optics and Professor of Physics at the University of Rochester.

Two-photon photovoltaic effect is an energy collection method based on two-photon absorption (TPA). The TPP effect can be thought of as the nonlinear equivalent of the traditional photovoltaic effect involving high optical intensities. This effect occurs when two photons are absorbed at the same time resulting in an electron-hole pair.

Integrated quantum photonics, uses photonic integrated circuits to control photonic quantum states for applications in quantum technologies. As such, integrated quantum photonics provides a promising approach to the miniaturisation and scaling up of optical quantum circuits. The major application of integrated quantum photonics is Quantum technology:, for example quantum computing, quantum communication, quantum simulation, quantum walks and quantum metrology.

References

  1. ↑ J.A. Armstrong; N. Bloembergen; J. Ducuing; P.S. Pershan (1962). "Interaction between light waves in a nonlinear dielectric". Physical Review . 127 (6): 1918. Bibcode:1962PhRv..127.1918A. doi: 10.1103/PhysRev.127.1918 .
  2. ↑ V. Berger (1998). "Nonlinear photonic crystals". Physical Review Letters . 81 (19): 4136–4139. Bibcode:1998PhRvL..81.4136B. doi:10.1103/PhysRevLett.81.4136.
  3. ↑ T. Xu; K. Switkowski; X. Chen; S. Liu; K. Koynov; H. Yu; H. Zhang; J. Wang; y. Sheng; W. Krolikowski (2018). "Three-dimensional nonlinear photonic crystal in ferroelectric barium calcium titanate". Nature Photonics . 12 (10): 591–595. Bibcode:2018NaPho..12..591X. doi:10.1038/s41566-018-0225-1. S2CID   125827524.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.