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10 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Some optical properties of KTP, LiIO3, and LiNbO3

Measurements of the absorption coefficient for KTP, LiIO3, and LiNbO3 are discussed. The variation of the refractive index with temperature has been measured for KTP and LiIO3. It is necessary to know both the absorption coefficient beta and the variation in the indexes of refraction with temperature change dn/dT to determine the average power limit of a nonlinear interaction. With the dn/dT information, it is also possible to estimate the temperature half width of any nonlinear interaction by calculating the variation of the phase-matching condition with temperature.

Gettemy, Donald J.↗
DOE OSTI2020

Materials Data on LiIO3 by Materials Project

LiIO3 crystallizes in the hexagonal P6_3 space group. The structure is three-dimensional. Li1+ is bonded to six equivalent O2- atoms to form face-sharing LiO6 octahedra. There are three shorter (2.11 Å) and three longer (2.18 Å) Li–O bond lengths. O2- is bonded in a 3-coordinate geometry to two equivalent Li1+ and one I5+ atom. The O–I bond length is 1.83 Å. I5+ is bonded in a 3-coordinate geometry to three equivalent O2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiIO3 by Materials Project

LiIO3 crystallizes in the orthorhombic Pna2_1 space group. The structure is three-dimensional. Li1+ is bonded to five O2- atoms to form distorted edge-sharing LiO5 trigonal bipyramids. There are a spread of Li–O bond distances ranging from 1.99–2.16 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted T-shaped geometry to two equivalent Li1+ and one I5+ atom. The O–I bond length is 1.82 Å. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Li1+ and one I5+ atom. The O–I bond length is 1.83 Å. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Li1+ and one I5+ atom. The O–I bond length is 1.83 Å. I5+ is bonded in a 3-coordinate geometry to three O2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiIO3 by Materials Project

LiIO3 crystallizes in the hexagonal P6_322 space group. The structure is three-dimensional. Li1+ is bonded to six equivalent O2- atoms to form LiO6 octahedra that share corners with six equivalent IO6 octahedra, edges with three equivalent IO6 octahedra, and faces with two equivalent LiO6 octahedra. The corner-sharing octahedral tilt angles are 48°. All Li–O bond lengths are 2.10 Å. O2- is bonded in a 4-coordinate geometry to two equivalent Li1+ and two equivalent I5+ atoms. Both O–I bond lengths are 2.13 Å. I5+ is bonded to six equivalent O2- atoms to form IO6 octahedra that share corners with six equivalent LiO6 octahedra, corners with six equivalent IO6 octahedra, and edges with three equivalent LiO6 octahedra. The corner-sharing octahedra tilt angles range from 48–50°.

36 MATERIALS SCIENCE↗
NASA NTRS1990

Absolute and relative nonlinear optical coefficients of KDP, KD(asterisk)P, BaB2O4, LiIO3, MgO:LiNbO3, and KTP measured by phase-matched second-harmonic generation

Both absolute and relative nonlinear optical coefficients of six nonlinear materials measured by second-harmonic generation are discussed. A single-mode, injection-seeded, Q-switched Nd:YAG laser with spatially filtered output was used to generate the 1.064-micron fundamental radiation. The following results were obtained: d36(KDP) = 0.38 pm/V, d36(KD/asterisk/P) = 0.37 pm/V, (parallel)d22(BaB2O4)(parallel) = 2.2 pm/V, d31(LiIO3) = -4.1 pm/V, d31(5 percentMgO:MgO LiNbO3) = -4.7 pm/V, and d(eff)(KTP) = 3.2 pm/V. The accuracy of these measurements is estimated to be better than 10 percent.

Eckardt, Robert C.↗
NASA NTRS1975

Photoinduced polarization properties of LiIO3 single crystal

Photoinduced polarization is achieved in a lithium iodate single crystal by the simultaneous application of a dc field and illumination from a uv source. The dark depolarization and photodepolarization current decay characteristics of the polarized samples have been studied in detail in this paper.

Pillai, P. K. C.↗
NASA NTRS1985

A study on inclusion formation mechanism in alpha-LiIO sub 3 crystals

The spatial distribution of inclusions in alpha-LiIO3 crystals by means of an argon laser beam scanning technique is studied. The effects of crystal dimensions and solution fluid flow on the inclusion formation in the alpha-LiIO3 crystals were observed. It was further shown that the fluid flow plays an important role in the formation of inclusions. The results obtained were further applied and verified by growing a perfect alpha-LiIO3 single crystal. An experimental foundation for further theoretical studies on the causes of inclusions may be provided.

Chen, W. C.↗
NASA NTRS1973

High-quantum-efficiency infrared up-conversion.

Experimental study in which 100% conversion of infrared photons into visible photons was achieved through three wave interactions in a nonlinear medium. The first experimental evidence of overconversion is presented, and the classical theory of up-conversion in the high-conversion-efficiency region is confirmed. A laser pump light feedback technique is described that promises to make the process practical with modestly powerful pump lasers and less than perfect nonlinear crystals. The nonlinear medium used was a LiIO3 crystal that cannot be 90-deg phase-matched. The 'walk off' that resulted helped make possible the attainment of 100% conversion efficiency.

Gurski, T. R.↗
NASA NTRS1979

Internal photoemission in Ag-Al2O3-Al junctions

The magnitude of the photon-induced current in Ag-Al2O3-Al metal-oxide-metal junctions has been studied as a function of photon energy and angle of incident radiation. Photocurrents were theoretically analyzed on the basis of a modified vacuum photoemission model (Jain, 1975; Slayman et al., to be published). Optical constants previously reported in the literature (Irani et al., 1971; Ehnrereich et al., 1963) were used to calculate the true spatial generation rate in Ag and Al as a function of the angle, polarization of incident radiation, and film thickness. Results were found to be in very good agreement with experimentally determined values for a tunable dye laser with a KDP doubling crystal pumped by a Q-switched Nd:YAG laser with a LiIO3 doubling crystal. The system provided risetimes of 50 ns or less and peak powers of 10 W. Under short circuit conditions, the photoresponse to incident power was linear up to available power densities of 10 kW/sq cm. Quantum efficiencies of about 0.1% at zero-bias, near 3.8 eV under P polarization, were typically observed.

Guedes, J. M. P.↗