Optical quasi-waveguide

Singh and Prasad observed optical bistability in a planar quasi-waveguide at 0.653 Mm and O.7 Mm wavelength with upper switching threshold power of 2.55 MW/cm and 3 86 MW/cm corresponding to extremely large values of nonlinear refractive index 5 10" cm /MW suggesting that it is a thermal effect. 

All the above results can be directly used in the problem of optical pulse propagation through the junctions provided that the quasi-static approximation is feasible. As the transmittance of a waveguide junction depends on power of a stationary component of the pulse, variation of an input pulse envelope behind the junction should be observed. 

The MMW region of the electromagnetic spectrum is characterised by quasi-optical electronic components for generation, transmission and detection. MMW sources and detectors are typically semiconductor devices with transmission lines of open tube rectangular waveguide, or coaxial cable at frequencies below 30 GHz. The cables are rather lossy and waveguide is the favoured transmission line for any other than the shortest links or where dielectric loss is less critical than mechanical flexibility, e.g. connecting to a frequency counter. 

Bortz, M. L., Arbore, M. A., and Fejer, M. M., Quasi-phase-matched optical parametric amplification and oscillation in periodically poled LiNbOj waveguides, Opt. Lett., 20, 49-51 (1995). 

Suhara, T., Morimoto, T and Nishihara, H., Optical second-harmonic generation by quasi-phase-matching in channel waveguide structure using organic molecular crystal, IEEE Photon. Technol Lett., 5, 934-937 (1993). 

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