Organic Nonlinear Material Research Articles

Properties of the Optically Nonlinear Organic Material Densely Doped in Matrices

Abstract Optical properties of densely doped organic optically nonlinear materials were investigated by means of optical absorption spectroscopy, optical harmonics generation, X-ray diffraction spectroscopy and pressure tuning spectroscopy. From the investigation of the absorption λmax, 2‐methyl‐4‐nitroaniline(MNA) in poly methyl methacrylate(PMMA) exhibited an intermediate character between the crystal and the MNA dissolved in the solvents, i.e., some type of “amorphous”, and in the regenerated cellulose(cellophane) almost the same character as the MNA crystal. These results were consistent with the X-ray diffraction analysis, the second and third harmonics generation and the pressure effect on the absorption λmax and fwhm.

Growth perfection and properties of organic non-linear materials

Microminiaturization of optical circuitry requires electro-optic materials of far greater efficiency than even the best currently available. The skill of the synthetic chemist can be used to create molecules of virtually any structure. Given sufficient knowledge to allow a detailed specification to be described, these synthetic capabilities allow organic crystalline materials to be `engineered' for optimum performance in a given context. The basic information allowing such crystal properties to be specified is currently extremely sparse. Nevertheless, already some fundamental principles of such `engineering' can be described. New materials, with performances approaching those required, are listed and their growth as large single crystals is outlined. The availability of such large low-defect-concentration crystals is a prerequisite for accurate characterization, so that, for the first time, this is now possible. The way is open for the creation of a source of reliable data from which the theory governing the performance of these materials can be fully developed.

Nonlinear optical devices: Relative Status of Polymeric Materials

ABSTRACTNonlinear optical phenomena have been investigated over the last three decades in many different materials and a great deal of progress has been made in both the basic science and device applications.(1] Although interest in nonlinear organic materials dates back to the early days of nonlinear optics, it is only in the last five years that progress has been sustained and rapid. The purpose of this paper is to examine progress in developing new nonlinear organic materials and in their application to devices for comparison with current state-of-the-art devices using other material systems.

Growth of bulk single crystals of organic materials for nonlinear optical devices: An overview

Highly perfect single crystals of nonlinear optical organic materials are required for use in optical devices. An overview of the bulk crystal growth of these materials by melt, vapor, and solution processes is presented. Additionally, methods that may be used to purify starting materials, detect impurities at low levels, screen materials for crystal growth, and process grown crystals are discussed.

Studies of non-linear optical organic materials: crystal and molecular structure of 2-dicyanomethylene-1,3-dioxolane

The structure of 2-dicyanomethylene-1,3-dioxolane has been determined from X-ray diffraction data. The compound crystallizes in the chiral space group Cc and has two molecules in the asymmetric unit. The correlation between the molecular packing and the second-harmonic generation (SHG) is discussed.

Organic second-order non-linear optical materials and devices

Organic second-order nonlinear materials are currently receiving considerable attention for fabrication of frequency mixing and electro-optic devices. In this paper the key concepts in the development of organic nonlinear materials and waveguide device design are introduced. The recent advances in nonlinear waveguides for frequency doubling and electro-optic devices are reviewed.

Application of Nonlinear Organic Materials to Femtosecond Light-Pulse Technology

Abstract Two experimental studies are presented illustrating applications of organic materials of high nonlinear refractive index to femtosecond light-pulse technology. One is intracavity pulse-compression of a colliding-pulse mode-locked dye laser with the addition of nonlinear organic materials into a saturable absorber solution. Another is femtosecond pulse compression external to the laser using nonlinear organic fibers. On the basis of the experimental results, the present problems and the optical properties that nonlinear organic materials should satisfy are discussed.

A Nonlinear Optical Organic Crystal for Waveguiding SHG Devices: (-)2-(α-Methylbenzylamino)-5-Nitropyridine (MBANP)

A nonlinear optical organic material, (-)2-(α-methylbenzylamino)-5-nitropyridine (MBANP), has been comprehensively investigated with the objective of application to frequency doubling of laser diodes. Its molecular hyperpolarizability is as large as that of p-nitroaniline. MBANP crystallizes with a highly asymmetric molecular arrangement. The largest nonlinear optical coefficient, d22, is measured to be 60 pm/V. The corresponding figure of merit for frequency doubling at 1.064 µm is 3.5 times larger than that for d33 of LiNbO3. Čerenkov-radiation-type, phase-matched second-harmonic generation has been demonstrated utilizing the d22 coefficient by making use of an appropriate waveguiding structure.

Linear and nonlinear optical properties of 2-(N-prolinol)-5-nitropyridine (pnp

Abstract 2-(N-prolinol)-5-nitropyridine (PNP) is a nonlinear optical organic material. Its linear and nonlinear optical properties have been investigated. The refractive indices and the orientation of the index ellipsoid were measured in the spectral range from 488 to 1064 nm. The two major nonlinear optical susceptibilities were determined (dyxx = 48 pm/V, dyyy = 17 pm/V). Angle tuned phase-matched second-harmonic generation was demonstrated at 1064 nm. The conditions for noncritical sum frequency generation were calculated.

Second harmonic generation from organic nonlinear materials of N-alkyl-4-nitroaniline

We have systematically investigated a series of new nonlinear organic materials, N-alkyl-4-nitroaniline, by measuring the second harmonic generation (SHG) from powder samples of the five materials with the alkyl chain of different length. It is found that N-butyl-4-nitroaniline (BuNA) shows the largest SHG activity among them, and the SHG intensity measured is 14 times larger than that of urea, in contrast with no SHG activity of para-nitroaniline. It is also found that BuNA is a phase-matchable material and the SHG efficiency has a strong dependency upon the recrystallization solvent used for purifying the reaction product.

Second-order nonlinear effects in asymmetric quantum-well structures.

The expression for second-order optical susceptibility based on band-to-band and intraband transitions in various asymmetric multiple-quantum-well structures is derived. The analogy with organic nonlinear materials is shown. The dependence of the second-harmonic coefficient and Pockels coefficient on well geometry, band offsets, and other material parameters is studied. The nonlinear and electro-optic coefficients of GaAs-${\mathrm{Al}}_{\mathrm{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$As asymmetric quantum-well systems are estimated to be in the range of most conventional nonlinear materials, while for proposed ZnSe-GaAs heterostructures these coefficients are found to be substantially larger than in conventional materials. Some practical applications of asymmetric quantum-well systems are discussed, including novel methods of phase matching. The case for engineering of novel nonlinear materials is made.

Intensity-dependent birefringence in nonlinear organic polymer waveguides

Low-loss monomode waveguides have been produced using polymer thin films extensively doped with a nonlinear organic material. We report the observation of an intensity-dependent birefringence in these waveguides, indicating the presence of a fast-acting intensity-dependent refractive index. The magnitude of the self-focusing coefficient n2 for these waveguides has been estimated as 6 × 10−19 m2/V2.

Solidification behaviour of organic nonlinear optical crystals

A representative rather than exhaustive review has been given on the solidification behaviour of organic nonlinear optical crystals. Many of the developments reported here represent quick experimental responses to the rapid theoretical advances made in the field of nonlinear optics. The article is divided into four parts. The first part deals with the characteristics of the organic nonlinear materials and need for large single crystals. The second and third parts are devoted to the thermophysical properties and experimental studies on crystallization processes. Here, recent work by authors is reviewed on the purification of source material, solidification behaviour and crystal growth. Various interactions between morphology, microsegregation, defects, growth velocity and temperature gradient are discussed. Specific examples of substituted anilines are presented. In the fourth section a stronger interaction is suggested between optical physicists and crystal growers to understand the problems of inhomogeneity, stress, damage threshold and doping in the organic crystals.

Intracavity femtosecond-pulse compression with the addition of highly nonlinear organic materials

It is experimentally shown that using organic materials of high nonlinear refractive index dissolved in a saturable-absorber solution permits femtosecond-pulse compression in a simple colliding-pulse mode-locked laser employing cavity-mirror dispersion adjustment.

Crystal growth and characterization of 4-(N,N-dimethylamino)-3-acetamidonitrobenzene, a new organic material for nonlinear optics

The linear and nonlinear optical properties have been determined for a new organic nonlinear material 4-(N,N-dimethylamino)-3-acetamidonitrobenzene. Room-temperature angularly tuned type I phase matching for doubling of 1.064 μm radiation was achieved with a deff =27 pm/V. Favorable crystal growth habits were observed.

Organic materials for nonlinear optical devices

Nonlinear optical effects offer devices which allow the control of a light beam with another light beam or an applied electric field. After a brief introduction to some nonlinear optical effects various organic materials and their applications in this area are discussed.

Recrystallization solvent effects on second-order nonlinear optical organic materials

Recrystallization solvent effects on second harmonic generation (SHG) of acetylene derivatives are reported. SHG intensities of substituted diphenylacetylene recrystallized from strong polar solvents are enhanced in crystalline states.

A New Intramolecular Charge Transfer Material for Nonlinear Optics: Piperonal Derivatives

ABSTRACTThis paper describes a new organic nonlinear material, piperoniridene ethyl cyano acetate which shows short cut-off wavelength, good nonlinearity (better than POM in powder) and good crystallinity. These features of this compound encourage its application in second harmonic generation (SHG) coupled with semiconductor laser.

Nonlinear Organic Materials in Integrated Optics Structures

ABSTRACTNonlinear organic materials, in conjunction with integrated optics structures, can potentially be used to perform a variety of all-optical operations on subpicosecond time scales. A number of potential devices are described and the material properties necessary to implement them are summarized. Progress in our laboratory toward these goals is detailed.

Amplification et émission paramétriques à l'échelle subpicoseconde dans un cristal organique : - application à la spectroscopie infra-rouge

High peak power subpicosecond optical pulses have been generated by parametric amplification of a white femtosecond continuum in a new organic crystal, N-(4-nitrophenyl)-L-prolinol (NPP). The relation between this observation and the structural properties, both at microscopic and macroscopic levels of NPP are exposed. Special emphasis is put on the renewal of the traditional concept of non-critical phase-matching in view of the present requirements linked to the observation of ultrafast subpicosecond nonlinear phenomena. The notions of θ-non critical and λ-non critical phase-matching together with their implications are exposed. A new method for time-resolved luminescence spectroscopy with subpicosecond resolution is simply derived as an extension of the NPP nonlinear measurement set-up where a previously used infra-red emitting continuum water cell is simply replaced by any sample of interest with luminescence in the 1.0-1.6 μm range. This new technique, defined as PASS, a tag for Parametric Amplification and Sampling Spectroscopy, is demonstrated at 1.44 μm in a InGaAs-InAlAs multiple quantum well structure. The future of nonlinear organic materials in infra-red optical signal processing systems is briefly discussed in conclusion Impulsions optiques de forte puissance crete obtenues par amplification parametrique d'un continuum de lumiere blanche dans le N-(4-nitrophenyl)-(L)-prolinol) ou NPP. Proprietes du NPP. Revision du concept «accord de phase non critique». Concept «d'accord de phase λ- non critique». Presentation d'une nouvelle methode spectroscopique autorisant une resolution temporelle inferieure a la picoseconde, methode «PASS» pour «Parametric Amplication and Sampling Spectroscopy». Application de PASS a l'etude d'une structure de type puits quantiques multiples