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Leaky waveguides for low ҡ-measurement: From structure design to loss evaluation

2016; SPIE; Volume: 9750; Linguagem: Inglês

10.1117/12.2208133

1996-756X

C. Wächter, Riccardo Rizzo, Francesco Michelotti, Peter Munzert, Norbert Danz,

Advanced Fiber Optic Sensors

For high quality optical coatings the knowledge of the losses of the deposited materials is essential. A precise measurement of low Im( n +iκ)≤ 10 -6 at an intended operation wavelength and with low intensity can be achieved in waveguide configurations, whereby leaky waveguide configurations allow one to analyze losses of high- and low-index media of H-L-stacks as well due to resonances in the angle-dependent reflection curve. Numerical investigations reveal that different leaky wave schemes, e.g. Bragg-, Bloch- and Antiresonant-Reflecting waveguides, comply differently with practical requests. Loss figure evaluation requires peculiar attention due to measurement accuracy and ambiguities, thus suitable constraints for layer data and a proper merit-function construction have to be used.