Second-order cascading as the origin of large third-order effects in organic single-crystal-core fibers

Optical studies on picoseconds response of optical switching 2-{3-[2-(3-methyl-4-methoxyphenyl)vinyl]-5,5-dimethylcyclo-hex-2-en-1-ylidene}malononitrile organic NLO material

An organic push-pull chromophores 2-{3-[2-(3-methyl-4-methoxyphenyl)vinyl]-5,5-dimethylcyclo-hex-2-en-1-ylidene}malononitrile(MOT2) was synthesized. The third order nonlinear optical property of MOT2 crystal was studied by using Z-scan technique with He-Ne laser (632.8 nm). The magnitude of nonlinear refractive index (n2), nonlinear absorption (β) and third order nonlinear susceptibility (χ(3)) have found to be in the range of 10(-14) m(2)/W, 10(-7) m/W and 10(-8) esu respectively. The multiphoton absorption and self defocusing effect were observed in z-scan open and closed aperture methods respectively. The response time of MOT2 crystal has found to be in the order of picoseconds, which is the essential requirement for the fabrication of optical switching. The optical transparency of MOT2 crystal was studied using UV-Vis-NIR spectroscopy and the reflectance, optical band gap (2.159 ev), extinction coefficient, optical conductivity were calculated. The refractive index of MOT2 crystal was measured using Abbe's refractometer and it is found to be 1.661. Photoluminescence study was carried out using Xenon lamp in a wavelength range of 450-700 nm. Laser optical damage threshold of MOT2 crystal was calculated using pulsed Nd-YAG laser of 1064 nm repetition rate of 10 ns.

Cascaded contributions to degenerate four-wave mixing in an acentric organic crystal

We show both theoretically and experimentally by degenerate four-wave mixing that the combined processes of optical rectification and the linear electro-optic effect contribute to the large effective third-order susceptibilities [14chi((3))(CS(2))] of the organic salt 4-N, N^- dimethylamino-4(?) -N(?) -methylstilbazolium toluene-p- sulfonate (DAST). Furthermore, the knowledge of the cascaded contributions was used to determine absolute values of the third-order susceptibilities as well as their sign.

Cerenkov second-harmonic generation in the strong conversion limit: new effects

Using beam propagation method calculations, we show that new effects occur for second-harmonic generation in the Cerenkov regime when it is optimized for efficient coupling to leaky modes. The fundamental throughput becomes independent of the input power over a few decades; i.e., optical power limiting is found. At even higher input powers, the fundamental throughput abruptly switches back to approximately the input power as a consequence of generating coupled second-harmonic-fundamental solitary waves in the waveguide because of the cascading effect.