A hollow waveguide with a uniform cross section may be used for accelerating charged particles if the phase velocity of an accelerating mode is equal to or less than the fiee space speed of light. Regular straight hollow waveguides have phase velocities of propagating electromagnetic waves greater than the free-space speed of light. if the waveguide is twisted, the phase velocities of the waveg...

We experimentally and numerically investigate the spatial distribution of the emission from a photonic crystal waveguide, coupled with defects, that are located at the output edge. Two defects that are located symmetrically enhance the directivity of the beam compared to that of a plain waveguide, as was reported in recently conducted theoretical work. We further demonstrate that a single defec...

This paper investigates the deformation of the eld transmitted through a square law medium waveguide. We consider the situation where the center of the waveguide randomly oscillates around the optical axis or the radius of the waveguide randomly pulsates. The random perturbations are small, but the waveguide is long, which gives rise to a macroscopic eeect of the inhomogeneities. This eeect is ...

We have fabricated quasi-phase-matched AlGaAs waveguides for continuous-wave second-harmonic generation (SHG) pumped around 1.55 microm. We find that the losses, which limit the conversion efficiency of this type of waveguide, are resulted from two corrugations--the initial template corrugation and the regrowth-induced domain-boundary corrugations. We are able to reduce the waveguide loss by im...

A new numerical technique is proposed for analyzing arbitrary shaped hollow waveguides. The method is based on mathematically modelling of physical response of a system to excitation over a range of frequencies. The response amplitudes are then used to determine the resonant frequencies. The results of the numerical experiments justifying the method are presented. The method is validated by cir...

We demonstrate that Raman spectroscopy can be used to characterize and identify particles that are trapped and propelled along optical waveguides. To accomplish this, microscopic particles on a waveguide are moved along the waveguide and then individually addressed by a focused laser beam to obtain their characteristic Raman signature within 1 second acquisition time. The spectrum is used to di...

In this paper a novel all-optical logic NAND, NOR and XOR gate based on nonlinear directional coupler theory is demonstrated. We use the identical structure which contains three waveguides, for designing these gates; the only difference however, is the power of inputs light beam. In other words, while a beam with 4 W/μm in power considered as logical one, the output is NAND gate and if a beam w...

In this paper, effects of the structural parameters on the optical characteristics of an add-drop filter, consisting of two straight waveguides and a micro-ring resonator (MRR), have been investigated. In this research, effects of MRR radius, the width of MRR and waveguide and the gap between MRR and waveguide, on free spectral range (FSR) and coupling coefficient have been studied. It is found...

In this paper a novel all-optical logic NAND, NOR and XOR gate based on nonlinear directional coupler theory is demonstrated. We use the identical structure which contains three waveguides, for designing these gates; the only difference however, is the power of inputs light beam. In other words, while a beam with 4 W/μm in power considered as logical one, the output is NAND gate and if a beam w...