Isabelle Ledoux

Linear and nonlinear optical properties of N-4-nitrophenyl L-prolinol single crystals

Abstract N-4-nitrophenyl-(L)-prolinol (NPP), an organic molecular crystal with application in quadratic nonlinear optics, has been characterized in terms of its absorption spectrum and refractive indices. A strong birefringence, with nχ−nz as high as 0.78 at 53 2 nm, is reported. All collinear phase-matching (PM) configurations in the principal planes for second harmonic generation (SHG) are subsequently identified; three of them correspond to effective nonlinear coefficients deff larger than 50 pm V-1 for SHG at 1.06 μm, with a factor of merit reaching 834 pm V-1. The most efficient PM configurations for near infrared SHG are close to normal incidence with respect to the cleavage plane of the crystal, allowing to take full advantage of the main molecular hyper-polarizability coefficient without projection factors. A θ-noncritical configuration at 1.15 μm corresponds to a deff value of 70 pm V-1, which remains, to the best of our knowledge, unsurpassed by other organic as well as inorganic crystals in the same spectral range.

New bipyridyl ligands bearing azo- and imino-linked chromophores. Synthesis and nonlinear optical studies of related dipolar zinc complexes†

The synthesis and optical properties of 4,4′-bis(dialkylaminophenylazo)-2,2′-bipyridine and 4,4′-bis(dialkylaminophenylimino)-2,2′-bipyridine ligands are described; the corresponding dipolar bipyridyl zinc dichloride complexes have been prepared and their second order nonlinear optical properties determined by electric field-induced second harmonic generation (EFISH) at 1.34 µm.

Crystal growth and characterisation of new organic nonlinear optical materials: 6-cyano and 6-nitro-2,2-dimethyl-3,4-epoxychroman

Two chiral organic nonlinear optical materials, (3S,4S)-(−)-6-cyano-2,2-dimethyl-3,4-epoxychroman (1) and (3R,4R)-(+)-6-nitro-2,2-dimethyl-3,4-epoxychroman (2), have been grown into single crystals of cm3-size. Although both compounds crystallise in the orthorhombic P212121 space group, they are not isomorphous and their crystal packings are quite different. Angle tuned type II phase-matched second harmonic generation between 0.8 and 1.064 μm has been evidenced, with effective nonlinear coefficients deff of 1 and 5 pm/V at 0.96 μm for 1 and 2, respectively. These values are in agreement with those estimated in the oriented gas model approximation using EFISH first order hyperpolarisability values (β0=2.6 and 4.0×10−30 esu for 1 and 2, respectively).

Synthesis and second-order nonlinear optical properties of new bipyridyl metal complexes

The synthesis and characterisation of a series of new π-donor substituted vinyl bipyridines and their rhenium, zinc and mercury complexes {donor = 4-R2N–C6H4–[R2N = Me2N, Bun2N, (Me)(OctnN)]; (η5-C5H5)Fe(η5-C5H4-)} with large nonlinear optical properties are presented; EFISH experiments at 1.34 µm show that complexation leads to a strong enhancement (by a factor of 3 to 9) of the molecular hyperpolarisability β(0).

Specific (bio-)chemical sensing with organic microlasers

Monitoring of environmental pollutants present at low concentrations requires creation of miniature, low-cost, and highly sensitive detectors that are capable to specifically identify target substances. We propose a detection approach based on refractive index sensing with polymer micro-lasers. The sensitivity and specificity of the detection is improved due to a functionalization of the microcavity material which allows specific detection of target molecules (here, heavy metal ions).

Chiral metal complexes with giant octupolar nonlinearities

nant dielectric susceptibility of the crystal and T is the duration of the accelerating optical pulse. Using a 100-picosecond pulse with an energy of 100 wJ, we expect a 5 3900 for Sr,.,Ba&bO, as nonlinear crystal and electron pulses whose initial velocity is 4 x 105 m/s. When space charge is included the pulse spreading has to be compensated by dispersion obtainable from the transverse profile of the accelerating beam. Figure 2 shows the results of numerical calculation of the electron pulse duration including the space charge effects evaluated as a function of the relative delay of the excitation pulse and the initial 50-femtosecond pulse producing electrons. As can be seen from the inset, pulses shorter than femtosecond can be obtained. 1. H. Niu, V. l? Schelev, Proc. SPIE Intem. Soc. Opt. Eng, 79,1032 ~(1989). J. C. Williamson, A. H. Zewail, Chem. Phys. Letters, 209 (1,2), 10 (1993). 2.