The availability of epitaxial ferroelectric films on semiconductor substrates would open up many options for integrated optics technology. There are significant materials issues involved in achieving this integration and we will report on progress toward optical waveguide fabrication on GaAs substrates. As a first step, we are investigating the fabrication of z-LiNbO3 waveguides on A12O3-c. The films have been deposited by off-axis rf magnetron sputtering and characterized by x-ray diffraction, atomic force microscopy, and scanning electron microscopies. Prism coupling has been used to determine waveguide thickness, indices of refraction and propogation losses. Issues concerning crystallography, texture, composition, surface roughness and processing will be discussed.

With the development of the short pulse laser source, it has been demonstrated that molecular [1–4] and lattice dynamics [5–7] can be studied in the time domain. Pulses of light that are short compared to the optical phonon period have been found to initiate coherent lattice vibrations through various mechanisms which depend on the material type. The purpose of this paper is to describe the observation of the coherent phonon phenomenon in semimetals and narrow-gap semiconductors, and to propose a potential application of this phenomenon as a terahertz light modulator.

By considering selected examples of new structure types, guidelines are set forth for the synthesis of new solid-state inorganic borates that are likely to have desirable properties for nonlinear optical applications. The structures of two new, noncentrosymmetric orthoborate fluorides BaCaBO3F and Ba7(BO3)3F5 demonstrate a feasibility for controlling linear optical properties and for producing noncentrosymmetric borates that melt congruently. The structure of SrLi(B3O5)3 represents an additional example of a noncentrosymmetric borate resulting from chirality of the B3O7 ring. In addition to potential practical value, crystals of the type AMOB2O5 (A = K, Rb, and Cs; M = Nb and Ta) provide a unique means for examining the structural dependent interrelationships of linear and nonlinear optical properties.

Device quality single crystals of potassium titanyl phosphate (KTP) have been grown using a top seeded solution growth method which incorporates a crystal weighing facility and which takes advantage of saturation temperatures well below the accepted transition temperature of this material. Weight and crucible temperature data are received and displayed on a monitoring computer in the form of a growth profile. Results obtained from the growth programme are discussed including the effect of very slow cooling (< 0.03 °C/hr) on the control of growth quality and a study of growth defects using x-ray diffraction topography carried out using synchrotron radiation. Variations on the standard K6P4O13 flux were investigated, including the addition of CeO2 to improve optical transmission and the use of K7P3O11 as an alternative growth solution.

Many inorganic crystals show strong nonlinear optical properties, and there still exists a need for new materials. One of them is barium borate existing in two modifications i.e. a high temperature phase α-BaB2O4 and low temperature phase β-BaB2O4. The β-phase in single crystal form (BBO) belongs to trigonal structure and possess high nonlinearity. The a-phase crystals are centrosymetric and for nonlinear applications are not useful. Attractive features of BBO crystals are: large nonlinear optical coefficients about six times higher as compared with KDP, large birefringence, transmision range between 190 and 3500 nm, damage threshold as high as 10 GW/cm2 measured with 100 ps pulses, low absorption, moisture insensitivity, and good mechanical and thermal properties. BBO crystals are used successfully for efficient generation of ultraviolet light from visible light source. They are suitable for use with the most powerful lasers for second and higher harmonic generation laser light and as an optical parametric amplifier (OPA) and optical parametric oscillator (OPO). Crystal structure of BBO has similarities with a molecular crystal structure and origin of its nonlinear properties is reminiscent of organic nonlinearity of organic crystals. The structure is built from B3O6 rings packed up perpendicularly along the c-direction of hexagonal unit cell.

The most widely used active elements of optically pumped solid state lasers are crystals of inorganic oxides. Such oxide materials crystallasing in either garnet or corundum structures are prepared on industrial scale by the pulling technique known as Czochralski Crystal Growth. The description of the present state-of-the-art in Czochralski growth is described along with critical variables involved in growth of large size, high quality oxide crystals. The description of crystal growth of ruby, yttrium aluminum garnets, and titanium sapphire is presented. The effects of compositions, ambient atmospheres, crystal growth variables, and environmental conditions on individual crystal types are described. Suitability of the Czochralski technique for crystal growth of different oxides is discussed with emphasis on material properties such as phase diagram implication (congruency of melting), melting temperatures, crucible materials, effects of doping ions, and high temperature melt chemistry.

A comparative study of the Czochralski crystal growth of Ca and Sr fluoro-phosphate, Ca and Sr fluoro- and chloro-vanadate is reported. Sr fluoro-phosphate and fluoro-vanadate demonstrate the best overall properties and crystal quality. Codoping of the fluoro-apatite crystals with Si4+ or Ge4+ ions increases the neodymium distribution coefficient but somewhat deteriorate the Nd3+ emission.

It is elaborated the crystal growth technique on base of Cyropulos method that allows to receive the sapphire single crystals of high quality with small dislocation density, low levels of X-ray luminescence and thermoluminescence, high transparency, and high radiation resistance. The main features of developed technique are: low temperature gradient in growth zone, acute-angled crystallization front, and absence of any mechanical displacement during growing process.

Some other growing factors influencing on crystal quality are discussed.

Fluorescence of silica fibers doped with Ce, Eu, Yb, Sm,Pr and Tb ions were obtained when excited by UV light, and also excited by Ar ion laser (514.5nm) and YAG laser(1.06 μ m), superfluorescence and upconversion fluorescence of Er-doped fiber were observed.

The specftral features of KTA samples, grown from melt solution of var ious solvent impurity composition and treated in various conditions are represented.

Intraband absorption in p-type In.53Ga.47 As has been measured at FIR frequencies (40–240 cm−1). It is found that the absorption in p-type InGaAs, which is associated with transitions between the light- and heavy-hole valence bands, is very strong. The absorption coefficient is as high as 103–104 cm−1. It increases with the doping concentration but decreases with the frequency of the incident radiation and temperature.

The author reports on idea of momentum effect of gaseous beam particles as to thin film epitaxial crystal growth such as molecular beam epitaxial growth or metal organic chemical vapor deposition epitaxial growth on stiffness of epitaxial growth thin film. The author presented that liquid glass encapsulation squeeze compression effect of liquid-glass-encapsulation Czochralski technique (LEC) crystal growth [Y.Saito, presented at the 10th Int. Conf. on Crystal Growth, 1992], third element different from crystal matrix elements [Y.Saito, presented at the 9th Int. Conf. on Ternary and Multinary Compounds, 1993], light momentum pressure of substance cooling thermal cycle [Y.Saito, presented at the 1st Int.Symposium on Laser and Optoelectronics Technology & Applications, 1993] can yield firmly binded bonds of substance elements. On the other hand, collisions of particles sputtered from solid target slabs [Y.Saito, presented at the 2nd Int.Symposium on Sputtering & Plasma Processes, 1993] or accelerated ions or particles evaporated from molten metals with themselves on the thin films can yield binded bonds. It was shown that internal compression in a crystal by ion implantation in crystal cell lattices can make the refractory state to gas phase chemical attack.[Y.Saito, in the Materials Research Society Symposium Proc. Vol. 279, pp. 135–140.] From these results, we can consider momentum effect at collision on binding state. After collision binding, internal compression by thermal transition variation in a multilayer structure during cooling thermal cycle influences binding stiffness.

This paper is devoted on Cr:LiSAF laser pumped by cw visible GaAlInP diode at 670nm. Ouput power of more than 60 mW at 850 nm has been obtained with a 500 mW pump laserdiode and the laser is tunable from 810 to 900 nm.

The effect of pressure on the spectrum and energy transfer properties of Cr3+:Tm3+:YAG has been considered. The results of cw and pulsed luminescence experiments are reported. The high pressure cw experiments demonstrate the existence of 1G4 → 3H5 emission from Tm3+. We believe this emission is also present in Tm3+:YAG at ambient pressure and has been previously misassigned. High pressure pulsed luminescence studies indicate a lengthening of the lifetime of Cr3+ in Cr3+:Tm3+.YAG and indicate that the rate of energy transfer from Cr3+ to Tm3+ decreases with increasing pressure. We interpret this result in terms of a destabilization of the 4T2 level of Cr3+ with increasing pressure.

X-ray Absorption Spectroscopy (XAS) of the Rare Earth (RE) 3d levels yields sharp peaks near the edges as a result of strong, quasi-atomic 3d104fn→3d94fn+1 (M4,5) transitions that contain a wealth of spectroscopic features. XAS is a useful technique for the characterization of 4f-occupancy, 4f-hybridization, and valence in RE-containing materials. The XAS measurements of the single crystal RE-orthophosphates, as well as a range of Ce- doped (˜l–30%) LaPO4 hosts were performed at the 3d edge in the total electron yield mode at beamline 8–2 at the Stanford Synchrotron Radiation Laboratory (SSRL). The XAS spectra of the RE ions in the orthophosphate matrix generally resemble that of the corresponding RE metal and emphasize the major contribution of the trivalent state to the electronic transitions occurring at the 3d edge. There is no energy shift of the La and Ce absorption peaks with Ce doping and furthermore, no additional transitions are observed in either spectral region. However, accompanying the Ce doping there is a significant narrowing of the La absorption peak full width half maximum that contrasts to the Ce features that exhibit no contraction. The La and Ce spectra indicate that the Ce-doping of LaPO4 is purely substitutional.

Homogenous tetragonal potassium lithium tantalate niobate (KLTN) crystals were grown using the flux pulling method. A two-wave-mixing gain coefficient of 0.5cm−1 has been measured using undoped KLTN. The gain coefficient can be increased to 2.7 cm−1 after doping of 0.2wt% Fe. The “cat” self-pumped phase conjugator was performed, for the first time, with KLTN:Fe crystal. We obtained a reflectivity of 14% and a response time less than 3 seconds using a frequency-doubled Nd:YAG quasi-continuous laser.

Femtosecond time-resolved optical techniques have been shown to generate coherent phonons in some semimetals and narrow gap semiconductors. A previously-reported model describes the mechanism for generation of coherent lattice vibrations via the optically excited carriers. One of the most interesting consequences of such coherent lattice motion is the modulation of the electronic bands - and possibly of the transport properties of the material — at a THz timescale. Preliminary results are given for a band structure calculation, performed to evaluate the magnitude of these laser-induced band shifts.

UV-spectroscopy method is used to study the influence ofdifferent varying growth parameters (growth rate, crystallization temperature, pH of the solution, complexating additions) on the absorption spectra of KH2PO4 crystals. It is found that the minimal value of the absorption coefficient (k ˜ 0.01–0.02cm−1)may be achieved under the following growth conditions: 1) crystallization temperature ˜ 55°C, 2) growth rate ˜ 1mm/24hrs, 3)pH = 4.

The effect of the crystal structure defects of different origin (dislocations, stresses, impurities, liquid phase inclusions) on the bulk laser damage threshold in big-size KDP crystals has been studied in the present paper. The quantitative dependence of the bulk laser damage threshold value on the internal stresses, density of dislocations and impurity concentration in crystals has been found.

Spectroscopic studies using laser induced fluorescence and numerical modelling of energy transfer and back transfer mechanism are reported in Er:Tm:Ho:YLF, Cr:Tm:Ho:YAG and Cr:Tm:YAG laser crystals at various temperatures (10 K-300 K). Direct energy transfer from Tm3+ excited states to Ho3+5I7 emitting level was observed and analyzed both in YAG and YLF. Further analysis of Cr3+ and Tm3+ time-dependent emission curves indicate a strong correlation of chromium-thulium pairs. Pulsed operation of holmium laser at high temperature will be presented.