Characterization Of A Three-Dimensional Etched Groove Separation Of Adjacent Optical Waveguides

A technique for inhibiting the optical channel interaction between two waveguides of a three-dimensional directional coupler structure is investigated. The technique, which uses an etched groove (slot) in the space between the channels, proved to be much more effective compared to the classical method of bending the waveguides away from each other to terminate interaction. Using the three-dimensional explicit finite-difference beam-propagation method, the characteristic parameters of the etched groove have been studied carefully to find the optimum case. We also show that the application of the groove is always accompanied by a small radiation power loss

A Stable Time-Domain Beam Propagation Method for Modeling Ultrashort Optical Pulses

A new technique to model ultrashort optical pulses is proposed and verified. The technique uses Pade approximant to account for the fast pulse propagational variations. Numerical parameters of the technique have been tested and it was shown that the method is simple, very stable, and accurate in modeli ng ultrashort optical pulses in long propagation interaction

Parallel efficient three-dimensional beam propagation method using the Du Fort-Frankel Technique

We implement the Du Fort-Frankel modified explicit finite-difference beam propagation method (MEFD) to model three-dimensional optical devices using parallel computers. Accuracy comparisons with other parallel FD-BPMs are made, and we observe that the MEFD is very accurate and efficient. The parallel implementation of MEFD shows a large run-time computer savings compared to other parallel FD-BPM algorithm

A Novel Nonparaxial Time-Domain Beam-Propagation Method for Modeling Ultrashort Pulses in Optical Structures

In this paper, a new nonparaxial time-domain beam-propagation method (TD–BPM) based on Padé approximant for modeling ultrashort optical pulses has been proposed and verified. The high efficiency of the technique in modeling long device interaction comes from solving the TD wave equation along one direction and allowing the time window to follow the evolution of the pulse. The accuracy of the method was tested in three different environments of homogenous and nondispersive medium, metallic, and dielectric waveguides and then was applied to model ultrashort pulse propagation in a directional-coupler device. The characterization of the technique shows excellent performance in terms of accuracy, efficiency, and stability, which the conventional paraxial TD–BPM failed to achieve. The new TD–BPM is particularly well suited for the study of unidirectional propagation of compact ultrashort temporal pulses over long distances in waveguide structures

IR laser ablative desulfurization of poly(1,4-phenylene sulfide)

Pulsed infrared laser-induced ablation (PLAD) of poly(1,4-phenylene sulfide) (PPS) results in the extrusion of sulfur and deposition of thin films that are a blend of initial PPS and sulfur–polyaromatic polymer composite. The process is demonstrated to differ from the conventional heating which leads to a solid material with S content and bonding similar to those in PPS. The PLAD of PPS thus represents a unique example of the desulfurization of S-containing polyaromatic materials

Characterization Of A Three-Dimensional Etched Groove Separation Of Adjacent Optical Waveguides

A technique for inhibiting the optical channel interaction between two waveguides of a three-dimensional directional coupler structure is investigated. The technique, which uses an etched groove (slot) in the space between the channels, proved to be much more effective compared to the classical method of bending the waveguides away from each other to terminate interaction. Using the three-dimensional explicit finite-difference beam-propagation method, the characteristic parameters of the etched groove have been studied carefully to find the optimum case. We also show that the application of the groove is always accompanied by a small radiation power loss

IR laser ablative desulfurization of poly(1,4-phenylene sulfide)

Pulsed infrared laser-induced ablation (PLAD) of poly(1,4-phenylene sulfide) (PPS) results in the extrusion of sulfur and deposition of thin films that are a blend of initial PPS and sulfur–polyaromatic polymer composite. The process is demonstrated to differ from the conventional heating which leads to a solid material with S content and bonding similar to those in PPS. The PLAD of PPS thus represents a unique example of the desulfurization of S-containing polyaromatic materials

A Stable Time-Domain Beam Propagation Method for Modeling Ultrashort Optical Pulses

A new technique to model ultrashort optical pulses is proposed and verified. The technique uses Pade approximant to account for the fast pulse propagational variations. Numerical parameters of the technique have been tested and it was shown that the method is simple, very stable, and accurate in modeli ng ultrashort optical pulses in long propagation interaction

Laser Ablative Structural Modification of Poly(ethylene-alt-maleic anhydride)

Pulsed IR laser ablation of poly(ethylene-alt-maleic anhydride) results in the deposition of polymeric films possessing the same ratio of anhydride and -CH2- groups and represents a very rare example of laser ablative deposition of polymeric films that are structurally identical to the ablated polymer. This process differs from the conventional thermolysis of poly(ethylene-alt-maleic anhydride) that is controlled by expulsion of CO2 and CO and yields a nonpolar polymeric residue. The IR laser ablation of poly(ethylene-alt-maleic anhydride) in sodium metasilicate affords deposition of polymeric films containing carboxylate (-CO2-) groups. This process is the first example of reactive ablation in which the deposited polymeric film incorporates constituents of two different species exposed to laser radiation

A time-domain beam-propagation method for analyzing pulsed optical beams in second-order nonlinear waveguides

The linear time-domain beam propagation method (TD-BPM) has been extended to model the propagation of pulsed optical beams in second-order nonlinear optical material of integrated waveguides. The coupled nonlinear wave equations have been derived and discretized using the explicit finite-difference method. The nonlinear TD-BPM method developed in the present work is very efficient, and is simple to implement