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Abstract-A passive polarization converter has been realized in silicon oxynitride (SiON) technology. The device is a grating assisted codirectional coupler consisting of segments of asymmetrically etched ridge waveguides. By using a double-masking technique, the fabrication of the device is tolerant with respect to the alignment of the required masks. Conversion efficiencies up to 0.98 (TE TM and TM TE) and insertion losses of 3 dB/cm have been measured. Using 2-D beam propagation method simulations, an observed beat pattern in the converter could be explained as due to a leaky mode, which is captured in the grating structure.

High-extinction on-off modulators are essential for channel selection in integrated-optical sensor arrays. We report a standard SiON-technology-based electrostatically driven integrated mechano-optical waveguide on-off intensity modulator. On-off modulation is achieved by movement of an absorbing element into and out of the evanescent field of the guided mode. An extinction ratio of >37 dB at an actuation voltage of <30 V was achieved in a 6 mm x 4 mm device for a wavelength of 632.8 nm. Full wafer-scale fabrication is made possible by use of chemical mechanical polishing and aligned wafer bonding.

In this paper, the design, fabrication and characterization of a sensor is presented, optimized for sensing changes of the absorption coefficient of a monomolecular transduction layer, while at the same time being insensitive to environmental absorption changes. A functional analysis of the device is given, relating the effect of technological uncertainties to systematic errors in the determination of the measurand. A physical implementation of the functional design based on dual mode interrogation, using a polarization converter and polarization splitter, is presented and fabricated. From a tolerance analysis, using the values of the applied SiON technology, it was derived that, over a range of 1 decade, this implementation allows for an inaccuracy of an uncalibrated sensor <10%. The performance characteristics of the individual subfunctions are given. Propagation losses are 1.6 dB cm-1 for both TE and TM polarized light. The relative wavelength shift of the resonance wavelength of the fabricated (grating assisted) polarization converters to its intended value is only 0.002. Experimentally, a 30 times decrease in the sensitivity to the output signal for changes in the absorption of the outer medium, compared to a monomodal sensor, has been observed.