Nonlinear Optical Figure Of Merit Research Articles

Effects of metal dopant (Ba2+), optical, and mechanical studies of bisthiourea zinc chloride NLO single crystals

Metal ion (Ba2+) doped bisthiourea zinc chloride (BTZC) crystals are grown from aqueous solution by slow evaporation technique. The physicochemical properties and non-linear optical figure of merit are found to be improved for the grown crystals. The lattice parameters are determined by single crystal X-ray analysis. UV spectral analyses on these samples reveal the improved transparency of the doped crystals ascertaining the inclusion of metal ion in the lattice. FTIR spectral analysis carried out on the materials confirm the presence of functional groups. Microhardness studies were carried out to confirm the mechanical behavior of the crystals. Low dielectric loss shows that the grown crystal contains lesser defects authenticating the suitability of the crystal toward device applications.

Design of SHG materials with mid-infrared transparency based on genetic engineering for Ba2BiInA5 (A = Se, Te)

We have employed genetic engineering through a four-step roadmap to design second-harmonic generation materials with infrared transparency. Firstly, we constructed virtual crystals of Ba2BiInA5 (A = Se, Te) using the “genome” BiA5 pyramid and InA4 tetrahedron. We then carried out reliable predictions of the crystal structures and revealed the asymmetric central group of these crystal compounds. Thirdly we carried out ab initio computations of the band structures and simulations of the optical properties. We surveyed the nonlinear optical figure of merit for the optical transparent range and the SHG parameters for these crystals. Finally, we provide evidence for the predictions by experimental synthesis, crystal structural determinations and optical measurements for the Ba2BiInSe5 compound.

High Electro-Optic Coefficient in Organic NLO Polymers: Poling and Study of the Relaxation Process

We report a high electo-optic coefficient (r33) of 175 pm/V in guest-host polymer films made by mixing amorphous polycarbonate with the chromophore, PYR-3 that was synthesized by our team. We have previously shown that PYR-3 has a large 2nd order nonlinear optical figure of merit. The measured r33 is five times larger than that of conventional inorganic materials such as lithium niobate. The decay of r33 with time has been studied for more than 1000 hours at room temperature and ambient atmosphere, and we find that the r33 value gradually reduced to a stable value of 34 pm/V after 40 days.

The effects of oxygen concentration and light intensity on the photostability of zwitterionic chromophores

Photostability measurements at different oxygen partial pressures and light intensities have been made on host-guest films containing amorphous polycarbonate and an organic chromophore with a high second order nonlinear optical figure of merit. We find that the photodegradation quantum efficiency dramatically increases with increasing oxygen partial pressure. At very low oxygen partial pressures (8×10−6 bar) the average number of photons required to photodegrade a chromophore is as high as 2×108 at 655 nm. The photodegradation quantum efficiency in air is observed to decrease with increasing optical intensity. We show that this is due to a reduced oxygen content in the film caused by chromophore photodegradation rather than ground state bleaching. There is an anomalous increase and then decrease in the photoluminescence intensity that cannot easily be explained.

Organic Materials for Third‐Order Nonlinear Optics

AbstractThe current status of organic low‐molecular weight and polymeric materials for third‐order nonlinear optics is reviewed. The importance of organic materials lies in their promise of large nonlinear optical figure of merit, high optical damage thresholds, ultrafast optical responses, architectural flexibility, and ease of fabrication. Organic materials exhibiting interesting third‐order nonlinear optical properties are discussed to illustrate the importance of structure–property correlations. Results on emerging organic materials that include liquids, dyes, fullerenes, charge‐transfer complexes, π‐conjugated polymers, dye‐grafted polymers, organometallic compounds, composites, and liquid crystals are presented. Organic nonlinear optical materials seem promising for a wide range of applications and their potential for integrated optics should be further explored.