Simple physics of quadratic spatial solitons

Spatial solitons in quadratically nonlinear media result from the interplay of parametric gain, diffraction and cascading phase shift. Their main features are well understood in mathematical terms, and several experiments have been successfully carried out which demonstrate their observability and most important properties. Here we provide an intuitive interpretation of some of the underlying physics, outlining the processes that govern their excitation, propagation and interaction forces

Wavelength dependence of 4-dimethylamino-4 \u27-nitrostilbene polymer thin film photodegradation

The polymeric electro-optical stilbene material, 4-dimethylamino-4 \u27-nitrostilbene (DANS), was illuminated at wavelengths ranging from the visible to near-infrared in order to quantify its photodegradation processes. Photodegradation due to one-photon and two-photon absorption was studied. The quantum efficiency of the chromophore degradation is found to be strongly wavelength and absorption mechanism dependent. This suggests that, in different regions of the spectrum, different excited states or different mechanisms are involved in the degradation process. In the near-infrared spectral region, operation lifetimes of electro-optic devices made from this chromophore are expected to be around only few hundreds hours, dramatically shorter than it was previously believed

Spatial Solitary Waves in Bulk Quadratic Non-Linear Materials and Their Applications

This invention encompasses generating electromagnetic solitary waves in two-transverse spatial dimensions. These wave beams propagate without diffraction and are equivalent to the normal modes of propagation of a nonlinear system governed by second order optical nonlinearities. The wave beams can be generated using optical techniques and will impact a wide variety of geometries and operating conditions whenever second order nonlinear optical processes are implemented for harmonic and parametric optical conversion. A preferred embodiment covers the generation of solitary waves from nonlinear materials such as KTiOPO.sub.4 (KTP) crystals. Other types of nonlinear optical device crystals can also be used such as KH.sub.2 PO.sub.4 (KDP), (NH.sub.2).sub.2 CO(Urea), LiNbO.sub.3, KNbO.sub.3, and the borate crystals BaB.sub.2 O.sub.4 (BBO) and LiB.sub.3 O.sub.7 (LBO)

All-optical multiphoton absorption figures of merit: Polydiacetylene poly (bis para-toluene sulfonate) of 2,4-hexadiyne-1,6 diol

The all-optical switching figures of merit are reported for the single crystal PTS (polydiacetylene poly (bis para-toluene sulfonate) of 2,4-hexadiyne-1,6 diol). Included are the effects of the absorption mechanisms from linear up to four-photon over the wavelength range 1.2-2.2 mum

One-Dimensional Spatial Solitary Waves Due To Cascaded Second-Order Nonlinearities In Planar Waveguides

We report an experimental observation of one-dimensional spatial solitary waves due to cascaded second-order optical nonlinearities

Cascading nonlinearities in an organic single crystal core fiber: The Cerenkov regime

The large nonlinear phase shifts imparted to the fundamental beam during Cerenkov second harmonic generation (SHG) in a DAN, 4-(N,N-dimethylamino)-3-acetamidonitrobenzene, single crystal core fiber are explained and modelled numerically. Cascading upconversion and downconversion processes leads to nonlinear phase shifts produced by the second order nonlinear coupling of the guided fundamental mode and the component of the Cerenkov second harmonic field trapped in the fiber cladding

All-Optical Switching Devices Based On Large Nonlinear Phase-Shifts From 2Nd Harmonic-Generation

We show that the large nonlinear phase shifts obtained from phase-mismatched second harmonic generation can be used to implement all-optical switching devices such as a nonlinear Mach-Zehnder interferometer and a nonlinear directional coupler

Two photon absorption and photo-induced polymerization in partially polymerized crystals of polydiacetylene poly 4,6-dodecadiyn-1,10-diol-bis(n-butoxycarbonylmethylurethane)

We investigated the validity of noninteracting molecular chain theories for fully polymerized polydiacetylene crystals by measuring the two photon absorption spectrum of poly[4,6-dodecadiyn-1,10-diol-bis(n-butoxycarbonylmethylurethane)] chains isolated in their monomer matrix and comparing the results to those obtained previously from polydiacetylene single crystals. Data were taken over 800-940 nm using Z-scan and the measurements were found to be consistent with previously measured results in polydiacetylene single crystal poly[bis(p-toluene sulfonate) of 2,4-hexadiyne-1,6-diol], indicating the validity of the isolated molecule theoretical approach. We also report a low photo-induced polymerization threshold

Two photon absorption and photo-induced polymerization in partially polymerized crystals of polydiacetylene poly 4,6-dodecadiyn-1,10-diol-bis(n-butoxycarbonylmethylurethane)

We investigated the validity of noninteracting molecular chain theories for fully polymerized polydiacetylene crystals by measuring the two photon absorption spectrum of poly[4,6-dodecadiyn-1,10-diol-bis(n-butoxycarbonylmethylurethane)] chains isolated in their monomer matrix and comparing the results to those obtained previously from polydiacetylene single crystals. Data were taken over 800-940 nm using Z-scan and the measurements were found to be consistent with previously measured results in polydiacetylene single crystal poly[bis(p-toluene sulfonate) of 2,4-hexadiyne-1,6-diol], indicating the validity of the isolated molecule theoretical approach. We also report a low photo-induced polymerization threshold

Quadratic soliton collisions

The details of two soliton collision processes were investigated in detail in a 1 cm long periodically poled KTP crystal for the case when the solitons were excited by inputting only the fundamental beam. The effects on the collision outcomes of the distance of the collision into the sample, collision angle and phase mismatch were measured for different relative phases between the input beams. At small angles ( around 0.4(0)) fusion, repulsion and energy transfer processes were observed, while at the collision angles approaching 3.2(0) the two output soliton beams were essentially unaffected by the interaction. The phase mismatch was varied from 3.5 to - 1.5pi for the 0.4(0) collision angle case. The output soliton separation at p input phase difference showed strongly asymmetric behavior with phase mismatch. In general, the measurements indicate a decrease in the interaction strength with increasing phase mismatch. All collision processes were performed in the vicinity of a non-critical phase matching