Optical phase conjugation of picosecond pulses at 1.06 mum in Sn(2)P(2)S(6):Te for wavefront correction in high-power Nd-doped amplifier systems.

We report, for the first time to our knowledge, on picosecondpulse optical phase conjugation using photorefractive Sn(2)P(2)S(6) crystals. For 7.2-ps pulses at 1.

A terahertz time-domain spectrometer for simultaneous transmission and reflection measurements at normal incidence.

We present a versatile terahertz time-domain spectrometer which allows reflection measurements at normal incidence and double pass transmission measurements in a single experimental setup. Two different modes for transmission measurements are demonstrated for precise measurements of transparent high or low refractive index materials, respectively. The refractive indices and absorption coefficients of cesium iodide, potassium bromide, sodium chloride, polytetrafluoroethylene (PTFE, Teflon), and silicon have been measured in the frequency range between 1.

Photonic crystal structures in ion-sliced lithium niobate thin films.

We report on the first realization of photonic crystal structures in 600-nm thick ion-sliced, single-crystalline lithium niobate thin films bonded on a lithium niobate substrate using adhesive polymer benzocyclobutene (BCB). Focused ion beam (FIB) milling is used for fast prototyping of photonic crystal structures with regular cylindrical holes. Unwanted redeposition effects leading to conically shaped holes in lithium niobate are minimized due to the soft BCB layer underneath.

High-resolution laser lithography system based on two-dimensional acousto-optic deflection.

We present an advanced high-resolution, compact laser lithography system for fast prototyping of complex integrated optics devices comprising microring resonators and photonic crystal structures. Precise and flexible structuring of photoresist patterns is achieved by combing three linear stages (xyz) for sample positioning and a two-dimensional acousto-optical deflector for laser beam steering and intensity control. A continuous wave diode laser operating at a wavelength of 375 nm is used to illuminate all types of photoresists including SU-8.

Influence of phenolic hydroxyl groups on second-order optical nonlinearity at an example of 2,4- and 3,4-dihydroxyl hydrazone isomorphic crystals.

We investigate the crystal structure and physical properties of 2,4- and 3,4-dihydroxybenzaldehyde-4-nitrophenylhydrazone (DHNPH) isomer crystals to understand the relation between molecular ordering with noncovalent interactions based on phenolic OH groups. The microscopic and macroscopic optical nonlinearities of 2,4- and 3,4-DHNPH crystals are investigated experimentally and theoretically by using density functional theory calculations. Although the two isomer crystals possess a very similar molecular orientation based on a similar supramolecular synthon, 2,4-DHNPH exhibits a 1.

Fast dynamic waveguides and waveguide arrays in photorefractive Sn(2)P(2)S(6) induced by visible light.

We report on dynamic waveguides and waveguide arrays induced beneath the surface of electro-optic Sn(2)P(2)S(6) crystals by visible light at 514 nm. The waveguide structures are generated by interband photoexcitation and drift or diffusion charge transport mechanism. These structures are probed nondestructively in the transverse direction with a beam at a longer wavelength.

Light deflection and modulation through dynamic evolution of photoinduced waveguides.

Light induced waveguides produced by lateral illumination of a hotorefractive crystal show a complex dynamic evolution upon removal of the sustaining applied electric field. Using this effect, deflection and modulation of the guided light is realized by taking advantage of the screening and counter-screening of the space charge distribution. The spot separation upon deflection can exceed 10 times the original waveguide width.

A hydrogen-bonded organic nonlinear optical crystal for high-efficiency terahertz generation and detection.

Broadband THz pulses have been generated in 2-[3-(4- hydroxystyryl)-5,5-dimethylcyclohex-2-enylidene]malononitrile (OH1) by optical rectification of sub-picosecond laser pulses. We show that OH1 crystals allow velocity-matched generation and detection of THz frequencies in the whole range between 0.3 and 2.

Fabrication and phase modulation in organic single-crystalline configurationally locked, phenolic polyene OH1 waveguides.

A novel and promising technique for the fabrication of electro-optically active single crystalline organic waveguides from 2-{3-(4-hydroxystyryl)-5,5-dimethylcyclohex-2-enylidene}malononitrile (OH1) is presented. OH1 is an interesting material for photonic applications due to the large electro-optic coefficients (r333 = 109+/-4 pm/V at 632.8 nm) combined with a relatively high crystal symmetry (orthorhombic with point group mm2).

Double phase conjugate mirror using Sn2P2S6 for injection locking of a laser diode bar.

We demonstrate double phase-conjugation in pure and Te-doped Sn(2)P(2)S(6), a semiconducting ferroelectric material, at the wavelength of 685 nm. We observe a phase conjugate reflectivity of more than 800% at an intensity ratio of the pump beams of 44 for Te-doped Sn(2)P(2)S(6). Using a laser diode bar emitting at 685 nm, we demonstrate double phase conjugation of three independent emitters of the laser diode bar with a single mode master laser.

Electro-optic single-crystalline organic waveguides and nanowires grown from the melt.

Organic nonlinear optical materials have proven to possess high and extremely fast nonlinearities compared to conventional inorganic crystals, allowing for sub-1-V driving voltages and modulation bandwidths of over 100 GHz. Compared to more widely studied poled electro-optic polymers, organic electro-optic crystals exhibit orders of magnitude better thermal and photochemical stability. The lack of available structuring techniques for organic crystals has been the major drawback for exploring their potential for photonic structures.

Optical microring resonators in fluorineimplanted lithium niobate.

We report on the production and characterisation of optical microring resonators and optical channel waveguides by using fluorine-ion implantation and planar structuring in lithium niobate. We demonstrate the production of single-mode planar waveguides by low fluence fluorine-ion implantation (?? = 2.5 x10(14) ions/cm(2)) into lithium niobate wafers.

Electro-optic and nonlinear optical properties of ion implanted waveguides in organic crystals.

We report on the electro-optic and nonlinear optical properties of waveguides produced by low fluence (Phi = 1.25x10(14) ions/cm(2)) H+ ion implantation in the organic nonlinear optic crystal 4-N,N-dimethylamino-4'-N'-methyl-stilbazolium tosylate (DAST). The profile of the nonlinear optical susceptibility has been determined by measuring the reflected second-harmonic generation efficiency from a wedged-polished sample at a fundamental wavelength of lambda(omega) = 1176nm.

Electro-optic Charon polymeric microring modulators.

We propose and demonstrate a new type of electro-optic polymeric microring resonators, where the shape of the transmission spectrum is controlled by losses and phase shifts induced at the asymmetric directional coupler between the cavity and the bus waveguide. The theoretical analysis of such Charon microresonators shows, depending on the coupler design, three different transmission characteristics: normal Lorentzian dips, asymmetric Fano resonances, and Lorentzian peaks. The combination of the active azo-stilbene based polyimide SANDM2 surrounded by the hybrid polymer Ormocomp allowed the first experimental demonstration of electro-optic modulation in Charon microresonators.

Photochemical stability of nonlinear optical chromophores in polymeric and crystalline materials.

We compare the photochemical stability of the nonlinear optical chromophore configurationally locked polyene 2-{3-[2-(4-dimethylaminophenyl)vinyl]-5,5-dimethylcyclohex-2-enylidene} malononitrile (DAT2) embedded in a polymeric matrix and in a single-crystalline configuration. The results show that, under resonant light excitations, the polymeric compound degrades through an indirect process, while the DAT2 crystal follows a slow direct process. We show that chromophores in a crystalline environment exhibit three orders of magnitude better photostability as compared to guest-host polymer composites.

Direct electron beam writing of channel waveguides in nonlinear optical organic crystals.

We report on optical channel waveguiding in an organic crystalline waveguide produced by direct electron beam patterning. The refractive index profile as a function of the applied electron fluence has been determined by a reflection scan method in the nonlinear optical organic crystal 4-N, N-dimethylamino-4'-N'-methyl-stilbazolium tosylate (DAST). A maximal refractive index reduction of Deltan1 = -0.

Effects of anisotropic diffraction on quadratic multisoliton excitation in noncritically p hase-matched crystals.

The generation of multiple quadratic spatial solitons aligned approximately along a crystal axis in a biaxial noncritically phase-matched crystal is shown theoretically and experimentally to be the consequence of anisotropic diffraction.

High-speed photorefraction at telecommunication wavelength 1.55 microm in Sn2P2S6:Te.

We demonstrated for what is the first time to our knowledge photorefractive two-wave mixing in a bulk ferroelectric crystal using cw light at the telecommunication wavelength 1.55 microm. In the Te-doped ferroelectric semiconductor Sn2P2S6 with absorption constant <0.

Two-dimensional type I quadratic spatial solitons in KNbO(3) near noncritical phase matching.

Experiments on the properties of quadratic, two-dimensional spatial soliton properties in KNbO(3) near and at noncritical phase matching (NCPM) are reported. The NCPM geometry leads to unique features such as a large angular bandwidth for soliton generation, weak dependence of soliton composition on intensity and incidence angle, and unique multisoliton-generation properties.

Electro-optic phase modulation in ridge waveguides of epitaxial K(0.95)Na(0.05)Ta(0.71)Nb(0.29)O(3) thin films.

Electro-optic modulation at lambda=1.5 mum has been demonstrated for the first time to the best of our knowledge in a ridge waveguide phase modulator produced in cubic potassium sodium tantalate niobate thin films epitaxially grown on potassium tantalate substrates exploiting the large quadratic electro-optic Kerr coefficient of R11 = 8.2x10(-17) m(2)/V(2).

Ion implanted optical waveguides in nonlinear optical organic crystal.

We report for the first time to our knowledge optical waveguiding in an organic crystalline waveguide produced by ion implantation. Using H+ ions a refractive index barrier suitable for waveguiding has been realized in the highly nonlinear optical organic crystal 4-N, N-dimethylamino-4'-N'-methyl-stilbazolium tosylate (DAST). The refractive index changes in the waveguiding region as a function of the distance from the surface have been measured.

Nonlinear optical co-crystal of analogous polyene chromophores with tailored physical properties.

A new organic nonlinear optical co-crystal based on analogous configurationally locked polyene chromophores with noncentrosymmetric packing exhibits a large macroscopic second-order nonlinearity with tailored physical properties.

Deep UV light induced, fast reconfigurable and fixed waveguides in Mg doped LiTaO(3).

Dynamic waveguides are induced beneath the surface of magnesium doped near-stoichiometric lithium tantalate by deep UV light at lambda = 257 nm using the interband photorefractive effect. The waveguides can be reconfigured in 10 ms at UV intensities of 100 mW/cm(2). We show the importance of the background illumination for the build-up of dynamic optical waveguides.

Measurement of the terahertz-induced phase shift in electro-optic sampling for an arbitrary biasing phase.

We present a simple method to correct for nonlinearities in the detection of terahertz (THz) transients by electro-optic sampling. The THz-induced phase shift of the optical probe beam is calibrated with an additional biasing phase from a variable wave plate. All the parameters that are needed for the determination of this phase shift can be directly measured, which makes the method insensitive to errors resulting from residual birefringences of the electro-optic material or imperfections of the wave plate.

High efficiency generation and detection of terahertz pulses using laser pulses at telecommunication wavelengths.

We report on the generation and detection of few-cycle THz pulses in the organic crystal DAST (4-N,N-dimethylamino-4'-N'-methyl stilbazolium tosylate) using the telecommunication wavelength 1.5 mum. A continuous spectrum from 1.