New method of surface characterization with a single-mode fiber to thin film coupler

Alok Kumar Das; Amar K. Ganguly; Anawar Hussain; Shila Ghosh; Bharat P. Choudhury

doi:10.1117/12.256202

4 November 1996 New method of surface characterization with a single-mode fiber to thin film coupler

Alok Kumar Das, Amar K. Ganguly, Anawar Hussain, Shila Ghosh, Bharat P. Choudhury

Proceedings Volume 2862, Flatness, Roughness, and Discrete Defect Characterization for Computer Disks, Wafers, and Flat Panel Displays; (1996) https://doi.org/10.1117/12.256202
Event: SPIE's 1996 International Symposium on Optical Science, Engineering, and Instrumentation, 1996, Denver, CO, United States

Abstract

The evanescent field coupling characteristics between a single-mode half coupler and a thin-film planar waveguide (PWG) placed on the substrate is discussed. The throughput fiber power T changes with the variation of the effetive thickness of the film. Experiments for different thicknesses of the PWGs are carried out. The . thickness of the spacer deposited on the substrate or the roughness of the substrate with fixed spacer, controls the effective thickness of the PWG. Thus, T measures the roughness quality of the substrate and also the thickness of the spacer. The substrate was fused silica for the standard telecommunication fiber as half coupler. However, coupling fiber was also used in the case of germania-silica substrate for matching the propagation constants fo the fiber and the substrate. The variation of T with the change of refractive index of PWG and also the substrate are also shown. Theoretical analysis was carried out and a good agreement is observed with the experimental results.

Citation Download Citation

Alok Kumar Das, Amar K. Ganguly, Anawar Hussain, Shila Ghosh, and Bharat P. Choudhury "New method of surface characterization with a single-mode fiber to thin film coupler", Proc. SPIE 2862, Flatness, Roughness, and Discrete Defect Characterization for Computer Disks, Wafers, and Flat Panel Displays, (4 November 1996); https://doi.org/10.1117/12.256202

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