We report on the recent development and initial test results of two electro-optic polymer based integrated optic devices for optical interconnection applications. The first is an optical railtap for the distribution of many different optical signals from a single CW laser diode, and the second is a traveling wave Mach-Zehnder integrated optic modulator, which was modulated at frequencies up to 8 GHz. Electro-optic polymer materials supplied by Akzo Research, By, were used in both devices.

Side chain polyrrers containing hyperpolarizable noieties as the periant groups have been applied as optically ncrilinear traterials to produce polyxreric integrat1 electro-optical devices . Phase nixiulators, intisity nixiulators (1ch-Zebzx1er interferaiters) aixi optical 2*2 sce switches ( 2*2 directixa1 nixie couplers) have been uncle . Driving voltages as 1ci as 2 Volts (V ) have been obtain1 for a 24 nm active 1gth çkmse ncdulator; 4.4 Volts (V ) for a 14 inn active 1angthch-Zebrx1er interferarter, ath 9 Volts for a 14 nm active length directionI node ccupler. Intisity nixiulation ratios of about -23 dB atti -17 dB have been derived for the intensity nixiulator atd nixie ccxipling switch, respectively. The device properties , theni.l arxi electrical stabilities , etc. will be discussed. The results obtained shcw that optically txnlinear polyiTers are attractive caixlidates for the realizaticzi of polyireric integrated electro-optical devices. In additicn, several passive veguiding devices have beai nnde.

The maturation of silicon as a system wide "macrointegrated" technology suggests extremely compact, powerful computing systems in which communication will be among the most important functions. A silicon wafer area communication network which has the transmission function performed optically, ideally offers significant performance advantages over an electrical implementation, provided that it can be integrated compatibly within the electronic environment. Here, the suitability of long distance lightwave techniques for achieving the desired interconnection functionality is considered. The adaptations to conventional optical networks made necessary by electronic system cointegration constraints as well as the emerging role of optical polymers in achieving these adaptations at the wafer level are explored.

We report on the design and characterization of methylmethacrylate copolymers with nonlinear optical 4-alkoxy-4'-alkylsulfone stilbene sidechains, which are transparent down to 410 nm. A fairly stable, polar orientation has been obtained by means of electric field poling, resulting in a reasonably high nonlinearity (d33 square; 9 pm/V). Phase matched second harmonic generation in planar waveguides of these polymers is achieved by means of spatially periodic photochemical bleaching of the stilbene sidechain.

Efficient phase matched second harmonic generation has been observed in a polymer waveguide over a distance of 0.5 cm. Phase matching is accomplished by periodic poling of a nonlinear optical polymer. The observed efficiency of 0.01 % /W is in good agreement with calculations.

Channel waveguides were fabricated using a nonlinear optical organic material (-)2-(a-methylbenzylamino)- 5-nitropyridine (MBANP) with the objective of application to the frequency doubling of laser diode light. Blue light was obtained by second-harmonic generation in the form of Cerenkov radiation using a laser diode source oscillating at A = 870 nm.

Nonlinear optically active compounds newly designed and synthesized in Frontier Research Program were reviewed: single crystal of dicyanovinyl anisole (DIVA) for blue light generation, one- or two-dimensional r -conjugated systems such as polythiophenes, polydiynes, soluble phthalocyanines and annulenes, for third order optical nonhinearities and waveguide application. As a promising technique to control the molecular orientation and assembly, the organic molecular beam epitaxy (OMBE) is proposed.

The femtosecond (fs) optical nonlinearities and dynamics of a guest-host organic material , 7-'[4-[ (4-hexyloxyphenyl) azo] (naphthyl) azo- (2 , 3-dihydro-l, 3-diinethyl-2--octyl) ] perimidine (DNP) doped poly (methyl inethacrylate) (PMMA) , were studied in thin film form. An all-optical NOR logic operation was demonstrated by constructing a nonlinear Fabry-Perot etalon with the guest-host material. The optical logic gate has a subpicosecond switch-on time. The switch-off time has a fast component of 4 picoseconds (ps) and slower components. Measurements of the excited state dynamics of the thin film indicate that the fast recovery is due to the electronic excited state lifetime of the DNP molecules. A contrast ratio of 1.7 between the switch-on and off states of the etalon gives a resonant nonlinearity of 6.7xlO9 cm2/kW for a 1 . 5 GW/cm2 pump intensity.

The third order nonlinear susceptibility, two photon absorption coefficient, 13, and linear absorption coefficient, a, for some rare-earth cyclopentadienyl compounds and dithiolene complexes have been measured. Resonantly enhanced x3 coefficients of up to 1011esu for dilute solutions have been determined. Trade off in the size of the nonlinear susceptibility, with loss, in materials with low two photon absorption leads us to believe that Stegeman1'2 figures of merit acceptable for some all-optical switching devices are achievable with such materials.

We report our investigations of the cumulenes, a novel class of compounds proposed for use as the active second- and thirdorder nonlinear optical component materials for electro-optic and all-optical devices. Unlike conjugated organic nonlinear optical molecules based on alternating multiple and single bonds, these molecules contain a contiguous, or "cumulated" system of double bonds, leading to a highly rigid one-dimensional backbone of polarizable ic-electrons. A series of symmetrically- and asymmetrically-substituted teiraphenyl cumulenes has been synthesized and characterized. D.C. electric field-induced second harmonic generation experiments show significant second-order nonlinear susceptibilities in a series of polar cumulenes. Preliminary results showing evidence of resonant and nonresonant third-order nonlinear optical activity are also reported.

The third order optical susceptibilities XIfli(-3w ; co, a, ) for PMMA films doped with a soluble metallophthalocyanine derivative are determined by optical third harmonic generation measurements at wavelengths of 1543nm and 1907nm. The x3 values are 6-7 times enhanced at resonant and nonresonant wavelengths, concurrent with an absorption change induced by solvent vapor treatment. The enhancement of third order optical nonlinear susceptibilities in phthalocyanine thin films is discussed in terms of molecular stacking.

The thin films obtained by a spin-coating of soluble co,per phthalocyanines with tetra-alkylthio substituents have been found to have the x kJ) values in the order of magnitude of l0h1 esu. It is almost the same value as that of metallophthalocyanine with an axial ligand, i.e., vanadiumu-oxo phthalocyanine and so on. Of the both phthalocyanines, Q-band absorption maxiffla shifted to the longer wavelength compared with those of the solutions, on the contrary to the shorter wavelength shift of the usual phthalocyanine. For the both phthalocyanines, it is estimated that any loose aggregation of molecules are facilitated by unsymmetrical substitution and/or permanent dipole to give enlarged x (3) values. Especially, in the spin-coating films of the present soluble phthalocyanines, the growth of the aggregation with the large x was recognized by the changes of absorption spectra and x-ray diffraction patterns.

Third order nonlinear optical properties of organic ladder copolymer (POL) system is studied using degenerate four-wave mixing with picosecond laser pulse. Both the real and imaginary part of the third order nonlinear susceptibility (3) were determined by a new phase conjugate interferometric method over the wavelength range of 532 - 720 nm. From the space symmetry and wavelength dependence of -) we attribute the observed nonlinearity to the nonlinear photoexcitation of bipolarion states in this ladder copolymer system.

During the past three years it has become more evident that long conjugation sequences in electroactive materials may not be a stringent requirement for high third order nonlinear optical (NLO) activity. Since long conjugation lengths in these materials often make them difficult to process, the resulting insolubility often precludes the formation of optical quality films for device applications. The incorporation of shorter electroactive segments alternating with flexible non-active spacers may allow high NLO activity coupled with good optical film forming capability. In this paper we would like to present several approaches to copolymer design which incorporate various electroactive oligomer segments with well-defined conjugation lengths. The control one obtains in this appmach allows the design of sharp optical windows, and the ability to tailor absorption characteristics to particular frequencies.

Colloidal, "quantum-dot" semiconductormaterials, as exemplified by the sharp-cut yellow-red filter glasses which contain small (less than 100 A diameter) crystallites of cadmium sulfide and/or cadmium selenide, are of current interest because of the large near-resonant third-order nonlinear optical response they exhibit. Because these semiconductors are generally soluble only in inorganic media, such as silicate glasses, they have not been considered widely as candidates for inclusion in organic polymer waveguides. We report here the initial results of a continuing study in which very small colloidal particles of both cadmium sulfide and cadmium selenide (with crystallite diameters of typically 30-50 A) have been prepared by the reverse-micellar technique and then "capped" with a variety of organic reagents, using the methodology described several years ago by Brus and Steigerwa1d14. By varying the organic capping reagent, we find that we are able to produce significant variations in both the solublilty and the nonlinear optical response of the resulting composite materials. In particular, we find that the solubility of the particles in organic polymers such as PMMA and polycarbonate varies greatly with the nature of the capping reagent, with corresponding changes in the nonlinear refractive index of the composites. The feasibility of developing organic nonlinear optical waveguides based on this approach will be discussed.

Results of investigations on polymer systems as third-order nonlinear optical materials are presented. A few doped polymer systems containing cyanine dyes have a large thirdorder nonlinear optical susceptibility x. Several amorphous polymers incorporating relectron conjugated units are also synthesized. Increases in x3 are shown to be due to longer yr-electron conjugation and acceptor-donor pairs.

Polydiacetylenes with attractive electro-optical characteristics are usually insoluble and infusible, so various kinds of fabrication method have been proposed in order to control them into desirable forms such as large single crystal, thin film etc. This paper deals with the successful results on fabrication of highly oriented polydiacetylene thin films by vacuum deposition process in combination with so-called substrate rubbing technique. The third order non-linear optical susceptibilities of thin films thus prepared are as large as around 1010(esu), which indicates the excellent optical quality of thin films comparable to that of polydiacetylene single crystals. The details of fabricating conditions, mechanism of oriented structure formation, properties and characteristics of thin films are presented.

In order to obtain the polydiacetylenes with aromatic substituents directly bound to the polymer backbone, many of unsymmetrical diacetylene derivatives with aromatic rings at one side and carbazolylmethyl at the other side of diacetylene moiety have been synthesized. Among them, 1-(3,5-bis(trifluoromethyl)phenyl)-5- (N-carbazolyl)-1,3--pentadiyne (DFCP) was found to be topochemically polymerized with complete conversion into the polymer single crystals. Spectroscopies and X- ray crystal structure analysis revealed that the fr-conjugation between the polymer backbone and the phenyl ring of this polymer are in the similar extent to those of the so-far prepared poly(diphenyldiacetylene)s in spit çf mono- aromatic-substituted polydiacetylene. Nearly the same magnitude of as the largest reported for polydiacetylenes was evaluated from third harmonic generation.

The complex composed of ionic polymer and ionic dye was investigated for third order nonlinear optics. The complexes were prepared by ion exchange reaction between sulfonic group of the polymers and cationic dyes. As cationic dyes, hemicyanines(HC-n), where n indicates the number of double bonds between the aromatic rings, oxacyanine(OC-1) and triphenylmethane derivatives were used. The dye content of the complex could be controlled with in the range of 0.1-0.6 molar ratio of bound dyes to the sulfonic groups by the composition of mixed solvents for the reaction. The thin films of complexes were made by spin coating of their CHC13/MeOH solution on fused quartz plates. They were transparent and homogeneous with naked eyes and polarizing microscope. THG measurements were performed by use of pumping laser light from 1.5im to 2.ljim. x3 values of every complexes were found to be linearly proportional to the dye content (M)(mmol/cm3). The x3 values of hemicyanine complexes became large at the pumping wavelengths in resonant region of every dyes, and x3 of HC-2 was always larger than that of HC-1, whereas that of OC-1 with a srnmetrical structure was ten times smaller than that of HC-1. The largest values attained at each maximum (M) and at the pumping of 1.5m were 1.8x10"esu for HC-1, 2.4x10"esu for HC-2 and 1.7x10"esu for Crystal Violet. However, in the case of Malachite Green and Basic Cyanine 6GH, their THG intensities were negligibly small even at resonant region.

A general enhancement mechanism is reviewed for nonlinear optical processes originating from real population of electronic excited states. The nonresonant third order optical susceptibility y1(-w4;wi,w2,w3) of quasi-one dimensional conjugated linear chains can be enhanced by orders of magnitude, or even change sign, when the first (S1), or second (52), electronic excited state is optically pumped and then populated for times suitably long to perform nonresonant measurements of y1(-w4; w1 , w2,w3) at frequencies different from the resonant pump frequency.

Organic polymeric materials offer great promise for the creation ofoptical guided-wave structures for use with silicon or gallium arsenide semiconductor devices. We have developed a number of new polymeric materials for which the refractive index may be photochemically controlled. These materials are ifiustrated by solid solutions of novel nitrone compounds in polymer hosts such as PMMA. We have demonstrated the creation of planar guided-wave structures in these materials both with direct laser writing and with traditional photolithographic techniques. We have also developed polymeric materials which are electro-optically active and which provide for the photochemical delineation ofguided-wave structures. We have utilized these materials to create electro-optic devices such as optical modulators.

We present transient measurements of the electro-optic response and the heterodyne technique used to monitor the poling process in-situ. Several of the measurements presented are made on a low-dopinglevel guest-host polymer to facilitate comparison with theory. Also presented are measurements on a stable poled side-chain polymer. The data indicate response rise and fall times of the order of milliseconds for the guest-host sample and the temperature dependence of those times is compared to the theoretical model. Good qualitative agreement between theory and experimental data is presented.

Using the dielectric spectroscopy in the frequency range I Hz to iO Hz the dielectric response of a suitable characterized (DSC, polarizing microscopy, X-ray diffraction) oriented film of a poly-[4-(4- Methacryloyloxybutoxy)-4'-nitrostilbene] could be detected. The relaxation in parallel alignment is interpreted as a s-process equivalent to the molecular reorientation process around the mesogen's short axis. The perpendicular alignment allows to detect dipole relaxation processes resulting from motions around the mesogen's long axis. A perfect alignment could be obtained in a strong magnetic field of 7 T. Using this method an oligomer with a molar weight of 2900 g/mol showed a completely transparent film of 75 tm thickness. The problems of chemical synthesis as well as a model for a molecular association are discussed.

Two different methods are described for measurement of the Pockels effect in a poled polymer film between planeparallel, semitransparent metal electrodes. Both are transmission experiments which can be performed at the same sample spot, using a common experimental set up. After a general description of the Pockels effect in electric field aligned sidechain polymers, the two measuring methods are described. Results of both types of measurements, obtained in a poled side-chain polymer with 4dimethylamino4'nitrostilbene (DANS) in the side group, are discussed.

A series of structurally modified polycarbonates (PC) have been demonstrated to have second-order nonlinear optical (NLO) activity. The dipolar functionality and NLO activity in these polymers are properties of the polymer backbone. d33 values of 0.08-1.35 x 1O esu were determined by second-harmonic generation (SHG) measurements using a Maker Fringe rotation approach. In-situ measurements of the NLO activity as a function of temperature during the parallel plate poling process show that the onset of the NLO activity occurs primarily near the polymer glass transition temperature. A study of the temporal stability of the NLO activity shows persistent NLO activity for at least 640 days after poling. An effective j per polymer repeat unit is calculated from the data and compared to PPP semi-empirical calculations ofj for model molecules. Agreement is shown to be best for carbonate-containing models of the polymer backbone. The approximate agreement of theory and experiment suggests that the orientability of the NLO active segments in the polymer backbone is adequately described by poling theory.

A novel Langmuir-Blodgett alternate layer system for second-order nonlinear optics is described and characterised by X-ray diffraction, second harmonic generation and Pockels effect measurements. Excellent deposition was achieved allowing the fabrication of a 301 layer film (thickness = O.95m). This was found to exhibit waveguiding. The effective indices of the guided modes were 1.52 for TM0 and 1.51 for TE0. Both the optical and X-ray diffraction results suggest the presence of some disorder in the molecular alignment within the films. This leads to a value of x2(-2w;'t,, w) = 19 x lO_12 m V' for one bilayer, falling off for an increasing number of bilayers.

Merocyanine - p-toluenesulufonic acid complex was investigated for the crystal structure and the optical properties. The molecules are crystallized in the space group P1 so that the crystal exhibits a large optical nonlinearity . The second order nonlinear optical coefficient d11 measured by means of the Maker Fringe ifiethod is 314pm/V as a pristine data and 500pm/V after the correction of scattering and is greater than d11 of 2-inethyl-4-nitroaniline.

The benzylidene-aniline derivative with an electron-donating group at 4-position and an electron-accepting group at 4'-position has been suggested by MO calculation, to have a small molecular dipole moment but a large second-order hyperpolarizability in comparison with those of p-nitroaniline analogous molecules, hence, to be a promising molecule on searching for a new organic crystal with large second-order optical nonlinearity. Chemical modification of the molecule suggested led to a discovery of a series of crystals having high activities in second harmonic generation ( SHG ) ; one of which, 4'-nitrobenzylidene-3-acetamino-4-methoxyaniline ( MNBA ) crystal in monodinic Cc with four molecules per unit cell showed larger powder SHG than 2-methyl-4-mtroaniline ( MNA ) crystal in a preliminary powder SHG experiment. A strongly polarized non-centrosymmetric molecular packing has been achieved in this crystal by the presence of intermolecular hydrogen bond between neighboring acetainino groups. Calculation by an oriented gas model with the use of the detailed structural data from X-ray analysis for the MNBA crystal predicted that the crystal may have up to ca. 2.9 times larger macroscopic optical nonlinearity than MNA crystal. This has been experimentally proven by measuring the d for SHG by Maker fringe method. The largest d coefficient was found to be dii , and the value obtained was 454 pm/V which is 1.8 times larger than d11 of MNA crystal and 13 times larger than of lithium mobate ( ) crystal.

It is important to control a polarization anisotropy, thus, a molecular alignment in obtaining such a crystal that can exhibit optimized phase-matchable second harmonic generation ( SHG ). Along with this view, we designed a novel dihedral rigid molecule which has two nitroaniline moieties rigidly connected each other through two adjacent sp3 carbons. We synthesized the molecules so designed and examined their crystals in SHG activities and phase-matching characteristics by a convenient powder method with a Nd:YAG laser. It has been found that one of crystals, namely, 3,9-dinitro-5a,6, ha, 12-tetrahydro[1,4]benzoxadino[3 ,2-bJ][1,4]- benzoxadine ( DNBB ) crystal manifests larger phase-matchable SHG than N-(4-nitrophenyl)-L-prolinol ( NPP ) crystal so far known as the typical efficient phase-matchable organic crystal. DNBB crystal has been shown to possess much improved material properties ; high thermal stability, distinguished hardness, insolubility to water, no sublimation, and high registivity to optical damage, for device applications in comparison with the crystals of p-nitroaniline derivatives reported so far.

Nonlinear susceptibilities of organic crystals are usually calculated from the molecular nonlinearities(hyperpolarizabilities) and the crystal structure data within the oriented gas model approximation. The effect of intermolecular interactions on hyperpolarizabilities, which is neglected in the approximation, is estimated quantitatively by using an ab initio molecular orbital(MO) method. Energy minimum crystal structures of typical organic nonlinear optical materials are calculated by an empirical atom-atom pairwise potential method.

300 types of "chalcone" derivatives excellent in blue light region transparency were synthesized to investigate on second harmonic generation(SHG). The results of investigation suggested that an alkoxy group, an alkylthio group and halogen were effective as a substituent. Besides, a single crystal with respect to 4-ethoxy-4 ' -methoxychalcone(C-607) and 1- (2-thienyl ) -3- (4- fflethylphenyl)propene-l-one(TC-28) were grown. The obtained crystals were high quality and large size over 5 cm. We also had the first success in continuous SHG on a intracavity of the microchip laser using this single crystal "chalcone".

Aiming at the shortening of absorption cut-off wavelength of inerocyanine, we prepared several stilbazoliuni derivatives. Their absorption bands are appreciably shifted to shorter and some of them have large SHG efficiencies. Among them, cyanostilbazolium p-toluenesolfonate complex has an absorption cut-off around 400nm and its nonlinear optical coefficient d33 is four times larger than d14 of POM.

A large Second Harmonic Generation (SHG) intensity which was 60 times as large as that of urea was observed in p-nitroaniline (PNA) I N-(p--nitrophenyl)ethylenediamine (NPEN) system. Results of X-ray and Scanning Electron Microscopy (SEM) analysis showed the new crystal structure. And this SHG intensity was related to cooling rate for solidification. The optimum cooling rate was in the range of 2°C/sec to 10°C/sec. Moreover, results of X-ray analysis and SHG measurements of similar binary systems showed that hydrogen bond and unique non- planar structure of NPEN played an important role for SHG and its stability.

Early work at Hoechst Celanese1 demonstrated that methacrylate polymers with mesogenic side chains could be made with reasonably large electro-optic activity. The mesogenic side chains are polar so that a non-centrosymmetric structure can be obtained by heating a film near its Tg in a strong d.c. electric field and thus orienting the side chains. In Figure 1, the general structure of methacrylate based electro-optic polymers using polar nitro-stilbene chromophores is shown.

This contribution reports a new approach to the synthesis of thin-film secondorder nonlinear optical (NLO) materials in which self-assembled chromophorecontaining multilayer structures are built up in the repeating reaction sequence: I3Si(CH2)2C6H4CH21 (Cp) , 4- [N,N-bis(3-hydroxypropyl)aminojstyryl-4' -pyridine (Ch), Cl3SiOSiCl2OSiCl3 (Si) , polyvinylalcohol (PVA) . The resulting multilayer structures have been characterized by optical and XPS spectroscopy, advancing contact angle measurements, null ellipsometry, and NLO properties. The latter mepirements reveal multilayer superlaces with good structural uniformity and that = 2 x l0 esu at A = 1064 nfl' (Xzz 6 x l0 esu for a single CpCh monolayer of 22 A estimated thickness).

Increased interest and activity in optoelectronics has resulted from anticipated applications of optics to communication, electronic interconnections, information storage and possibly even logic. Current nonlinear optical (NLO) devices today employ inorganic crystals, such as lithium niobate for electrooptic modulation and switching and KDP or KNbO3 for frequency doubling. Organic nonlinear optical materials, that is, poled organic polymeric films and organic crystals, have the potential to replace some of these inorganic crystals.1 Key advantages include the high intrinsic nonlinearities of some organic molecules, the ability to optimize the molecular structure for specific applications, low dc dielectric constant, and low temperature processing. Current progress has also been made in improving the long term stability of these materials. Here we wish to report on some of our recent results on measurements of the order parameter, new crosslinked polymeric materials which exhibit more stability and some device applications with polymeric materials and organic crystals.

Nonlinear triplet-triplet absorption in organic molecules can be used to construct all-optical switches and spatial light modulators. Experimental results using films of eosin in polyvinylacohol are presented and compared with theoretical calculations.

The performance of optically bistable liquid crystal interference filters with extra-cavity metallic absorbers is contrasted with designs using intra-cavity dyes with which switching levels at 4 pW are recorded. The use of these devices in parallel processing applications is also considered, with the optical implementation of a "flip-flop" and results of a 15 x 15 element array switching presented.

Ferroelectric liquid crystals have been the subject of investigation, ever since its discovery as a display element in dynamic display systems. Electro-optic studies show that most of the materials exhibits a permanent switched state above a threshold field. It rarely exhibited a linear proportiotnality of transmitted light with applied field. In this paper a new material has been investigated. Electro-optic switching characteristics in bulk samples of ferro-electric liquid crystal, 4'-(n-Octyl Benzoloxy) -4- (2-Octyloxy) Biphenyl [OBOB]gwere studied for various pulse widths of the applied field. It shows three distinct regions of response. For large pulse widths, above a threshold field, a permanent switched state with maximum intensity of light transmission was achieved. This corresponds to the expected ferroelectric liquid crystal switching behaviour. For medium pulse widths the intensity of the transmitted light varies directly as the applied field over a particular range of pulse widths. This region of response, where the intensity of light is modulated with the applied field is the one most suited for device application.

A new oranometaItc cornplex NLO crystal---Thioseiniiarbazide Cadiium Thiocyanate(TSCCTC) has been qrown from aquious soliiLion by temperature Iowerinq method.TSCCTC hetonis to orthoqonal ;ystern;space qroup P212121,and the unit cell paranwters are a.764, b:lO.765K1) cl2.9781I(1)A. The .rystat structure, tiiiear and nonlinear optical properties of TSCCTC are presented in this liaper.

Tri-Attyithiourea Cad*iu Chloride (ATCC) belongs to triqonat syste,space group R3c with ab11.S27(4),c27.992(4)A.Its PM properties and 3MG effects were studed and the whole nonlinear optical coefficients were obtained by MF iethxl.

Recentty,orqarnaetatlic couptex crystals have attracted peoples in the exploration of new nonlinear optical and uLtifunctionat aateriats.This is because of their wide transparent ranqe: , Large nonlinear optical susceptibiLities, stable chemicaL and good sechanicat properties. Followinq the double group structure aodeL1,we have found and qrn a series of organometatlic complex crystals----BTCC2,TSCCC3,ATCC4.After AItC,we have discovered and grown several new crystats--Altylthiourea Cadiii(Mercury) Ihtoride or Bro.ideM[QI21HO12MItH,} 3X2, M= Cd, Hg;xCl,Br.Their poier SHG efficiencies are all largerthan that of IJrea.This paper sainty reports the growth. structure and properties of Tri-Allyithiourea Cadaii Bromide(ATtB)

We present electric-field induced second-harmonic generation measurement results on the hyperpolarizabilities of donor-acceptor substituted aromatics. Those with strongly inductive accepting groups, such as the fluoromethyl carbonyl, perfluoroalkyl sulfonyl, and perfluoroalkyl sulfonylsulfimide groups, afford favorable trade-off between quadratic optical nonlinearity and optical transparency. Their relatively large molecular dipole moment and hyperpolarizability products (4) as well as high transparency in the visible region suggest promising applications in the frequency conversion of short wavelength diode lasers. The inductive contribution is found to be short ranged, being most effective in the relatively compact benzene derivatives but less so in the extended stilbene structures. Dispersive enhancements of hyperpolarizabiities at 1064 and 810 nm are also reported.

The electro-optic properties of polymeric materials are characterized using Fabry-Perot etalons in which the polymeric layer acts as the spacer layer. This technique is particularly useful since the etalon converts small electric field induced changes in the index of refraction of the spacer layer to changes in the overall transmittance and reflectance of the structure. In this paper we show that using angle tuning, the transmission characteristics of the Fabry-Perot etalons fabricated on glass substrates can be sufficiently characterized to allow for determination of the electro-optic coefficients of the spacer layer material. We also present experimental results of novel reflection mode etalons fabricated on Si. These structures exhibit a large change in reflectance as a function of the optical path length inside the etalon cavity. When fabricated with an electrooptic spacer layer, the reflectance can be modulated by applying an electric field. Reflection mode devices can also be used to study the properties of new eleciro-optic materials and also show promise for use as Si compatible modulators.