Lithium niobate

Hexagonal crystal structure of LiNbO₃

Lithium niobate (Li Nb O₃) is a compound of niobium, lithium, and oxygen. Lithium (ˈlɪθiəm is a Chemical element with the symbol Li and Atomic number 3 Niobium (naɪˈoʊbiəm or columbium (/kəˈlʌmbiəm/ is a Chemical element that has the symbol Nb and Atomic number 41 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Niobium (naɪˈoʊbiəm or columbium (/kəˈlʌmbiəm/ is a Chemical element that has the symbol Nb and Atomic number 41 Lithium (ˈlɪθiəm is a Chemical element with the symbol Li and Atomic number 3 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the It is a colorless solid that is insoluble in water. Its melting point is 1257 °C and its density is 4. 65 g/cm³. Its CAS number is [12031-63-9]. CAS registry numbers are unique numerical identifiers for Chemical compounds Polymers biological sequences mixtures and Alloys They are also referred to

Lithium niobate crystals have a trigonal crystal system and belongs to the 3m (C_3v) crystallographic point group. In Crystallography, the rhombohedral (or trigonal) Crystal system is one of the seven lattice point groups named after the two-dimensional A crystal system is a category of Space groups which characterize Symmetry of structures in three dimensions with Translational symmetry in three directions In Crystallography, a crystallographic point group is a set of Symmetry operations like rotations or reflections that leave a point fixed while moving each atom Its crystal structure lacks inversion symmetry and displays ferroelectricity, the Pockels effect, the piezoelectric effect, photoelasticity, and nonlinear optical polarizability. Reflection symmetry, line symmetry, mirror symmetry, mirror-image symmetry, or bilateral symmetry is Symmetry with respect Ferroelectricity is a physical property of a material whereby it exhibits a spontaneous electric polarization, the direction of which can be switched between equivalent The Pockels effect, or Pockels electro-optic effect produces Birefringence in an optical medium induced by a constant or varying Electric field. Piezoelectricity is the ability of some materials (notably Crystals and certain Ceramics including bone to generate an Electric potential in response to Photoelasticity is an experimental method to determine stress distribution in a material Nonlinear optics (NLO is the branch of Optics that describes the behaviour of Light in nonlinear media, that is media in which the dielectric polarization

Lithium niobate is has negative uniaxial birefringence which depends slightly on the stoichiometry of the crystal and on temperature. Birefringence, or double refraction, is the decomposition of a ray of Light into two rays (the ordinary ray and the extraordinary ray It is transparent for wavelengths between 350 and 5200 nanometers, and has a bandgap of around 4 eV. A nanometre ( American spelling: nanometer, symbol nm) ( Greek: νάνος nanos dwarf; μετρώ metrό count) is a In Solid state physics and related applied fields a band gap, also called an energy gap or bandgap, is an energy range in a solid where no electron states

It can be doped by magnesium oxide, which increases its resistance to optical damage (also known as photorefractive damage) when doped above the optical damage threshold. Magnesium oxide, or magnesia, is a white solid Mineral that occurs naturally as Periclase and is a source Other available dopants are Fe, Zn, Hf, Cu, Gd, Er, Y, Mn and B, creating optical sources that can be modulated by traveling-wave waveguide modulators. Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 Zinc (ˈzɪŋk from Zink is a Metallic Chemical element with the symbol Zn and Atomic number 30 Hafnium (ˈhæfniəm is a Chemical element that has the symbol Hf and Atomic number 72 Copper (ˈkɒpɚ is a Chemical element with the symbol Cu (cuprum and Atomic number 29 Gadolinium (ˌgædəˈlɪniəm is a Chemical element that has the symbol Gd and Atomic number 64 Erbium (ˈɝbiəm is a Chemical element with the symbol Er and Atomic number 68 Yttrium (ˈɪtriəm is a Chemical element with symbol Y and Atomic number 39 Manganese (ˈmæŋgəniːz is a Chemical element, designated by the symbol Mn. Boron (ˈbɔərɒn is a Chemical element with Atomic number 5 and the chemical symbol B. A traveling-wave tube (TWT is an electronic device used to amplify Radio frequency signals to high power usually in an electronic assembly known as a traveling-wave

Single monocrystals of lithium niobate can be grown using the Czochralski process. A single crystal, also called monocrystal, is a Crystalline Solid in which the Crystal lattice of the entire sample is continuous and unbroken The Czochralski process is a method of Crystal growth used to obtain Single crystals of Semiconductors (e They are used in laser frequency doubling, nonlinear optics, Pockels cells, optical parametric oscillators, Q-switching devices for lasers, other acousto-optic devices, optical switches for gigahertz frequencies, etc. A laser is a device that emits Light ( Electromagnetic radiation) through a process called Stimulated emission. Second harmonic generation ( SHG; also called frequency doubling) is a nonlinear optical process in which Photons interacting with a nonlinear Nonlinear optics (NLO is the branch of Optics that describes the behaviour of Light in nonlinear media, that is media in which the dielectric polarization The Pockels effect, or Pockels electro-optic effect produces Birefringence in an optical medium induced by a constant or varying Electric field. An optical parametric oscillator (OPO is a Parametric oscillator which oscillates at optical frequencies Q-switching, sometimes known as giant pulse formation, is a technique by which a Laser can be made to produce a pulsed output beam Acousto-optics is a branch of Physics that studies the interactions between sound waves and light waves especially the Diffraction of Laser Light In Telecommunication, an optical switch is a Switch that enables signals in Optical fibers or Integrated optical circuits (IOCs to be selectively It is an excellent material for manufacture of optical waveguides. An optical waveguide is a physical structure that guides electromagnetic waves in the optical spectrum

Lithium niobate is used extensively in the telecoms market, eg. in the mobile telephones and optical modulators. An optical modulator is a device in which a signal -controlled element is used to modulate a Beam of Light. It is the material of choice for the manufacture of surface acoustic wave devices. A surface acoustic wave ( SAW) is an Acoustic wave traveling along the surface of a material having some elasticity, with an Amplitude that

For some uses it can be replaced by lithium tantalate, Li Ta O₃. Lithium tantalate (LiTaO3 is a crystalline solid which possesses unique Optical, Piezoelectric and Pyroelectric properties which make it valuable Lithium (ˈlɪθiəm is a Chemical element with the symbol Li and Atomic number 3 Tantalum (ˈtæntələm (formerly tantalium /tænˈtæliəm/ is a Chemical element with the symbol Ta and Atomic number 73 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the

1 Periodically poled lithium niobate (PPLN)
2 Sellmeier equations
3 References
4 External links

Periodically poled lithium niobate (PPLN)

Periodically poled lithium niobate (PPLN) is a domain-engineered lithium niobate crystal, used mainly for achieving quasi-phase-matching in nonlinear optics. Quasi-phase-matching is a technique in Nonlinear optics which allows a positive net flow of energy from the pump frequency to the signal and idler frequencies by creating a periodic Nonlinear optics (NLO is the branch of Optics that describes the behaviour of Light in nonlinear media, that is media in which the dielectric polarization The ferroelectric domains point alternatively to the +c and the -c direction, with a period of typically between 5 and 35 µm. Ferroelectricity is a physical property of a material whereby it exhibits a spontaneous electric polarization, the direction of which can be switched between equivalent A micrometre ( American spelling: micrometer; symbol µm) is one millionth of a Metre, or equivalently one thousandth of a Millimetre The shorter periods of this range are used for second harmonic generation, while the longer ones for optical parametric oscillation. Second harmonic generation ( SHG; also called frequency doubling) is a nonlinear optical process in which Photons interacting with a nonlinear An optical parametric oscillator (OPO is a Parametric oscillator which oscillates at optical frequencies Periodic poling can be achieved by electrical poling with periodically structured electrode. Periodic poling is formation of layers with alternate orientation in a Birefringent material Controlled heating of the crystal can be used to fine-tune phase matching in the medium due to a slight variation of the dispersion with temperature. Nonlinear optics (NLO is the branch of Optics that describes the behaviour of Light in nonlinear media, that is media in which the dielectric polarization

Periodic poling uses the largest value of lithium niobate's nonlinear tensor, d₃₃= 27 pm/V. Quasi-phase matching gives maximum efficiencies that are 2/π (64%) of the full d₃₃, about 17 pm/V

Other materials used for periodic poling are wide band gap inorganic crystals like KTP (resulting in periodically poled KTP, PPKTP), lithium tantalate, and some organic materials. Periodic poling is formation of layers with alternate orientation in a Birefringent material In Solid state physics and related applied fields a band gap, also called an energy gap or bandgap, is an energy range in a solid where no electron states Potassium titanyl phosphate (KTiOPO4 or KTP is a nonlinear optical material which is commonly used for frequency doubling diode pumped Potassium titanyl phosphate (KTiOPO4 or KTP is a nonlinear optical material which is commonly used for frequency doubling diode pumped Potassium titanyl phosphate (KTiOPO4 or KTP is a nonlinear optical material which is commonly used for frequency doubling diode pumped Lithium tantalate (LiTaO3 is a crystalline solid which possesses unique Optical, Piezoelectric and Pyroelectric properties which make it valuable

Sellmeier equations

The Sellmeier equations for the extraordinary index are used to find the poling period and approximate temperature for quasi-phase matching. Jundt^[1] gives

$n^2_e = 5.35583 + 4.629 \times 10^{-7} f + {0.100473 + 3.862 \times 10^{-8} f \over \lambda^2 - (0.20692 - 0.89 \times 10^{-8} f)^2 } + { 100 + 2.657 \times 10^{-5} f \over \lambda^2 - (11.34927 )^2 } - 1.5334 \times 10^{-2} \lambda^2$

valid from 20-250 degrees Celsius for wavelengths from 0. 4 micrometer to 5 micrometers. A micrometre ( American spelling: micrometer; symbol µm) is one millionth of a Metre, or equivalently one thousandth of a Millimetre

Deng^[2], with measurements at longer wavelengths, gives the following

$n^2_e = 5.39121 + 4.968 \times 10^{-7} f + {0.100473 + 3.862 \times 10^{-8} f \over \lambda^2 - (0.20692 - 0.89 \times 10^{-8} f)^2 } + { 100 + 2.657 \times 10^{-5} f \over \lambda^2 - (11.34927 )^2 }- (1.544 \times 10^{-2} + 9.62119 \times 10^{-10} \lambda) \lambda^2$

valid for T = 25 to 180 degrees Celsius, for wavelengths between 2. 8 and 4. 8 micrometers. In these equations $λ$ is in micrometers and $f = (T-24.5)\times(T+570.82)$ where $T$ is in degrees Celsius.

References

^ Dieter H. Jundt (1997). "Temperature-dependent Sellmeier equation for the index of refraction $n e$ in congruent lithium niobate". Optics Letters 22: 1553.
^ LH Deng et al. (2006). "Improvement to Sellmeier equation for periodically poled LiNbO $3$ crystal using mid-infrared difference-frequency generation". Optics Communications 268: 110.

External links

Inrad data sheet on lithium niobate

Dictionary

-noun

(chemistry) the lithium salt of niobic acid, LiNbO₃, whose transparent crystals are used lasers and other optical devices

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