Robert Raimond Wijn

Realization of a multichannel integrated Young interferometer chemical sensor

We report on the design, realization, and characterization of a four-channel integrated optical Young interferometer device that enables simultaneous and independent monitoring of three binding processes. The generated interference pattern is recorded by a CCD camera and analyzed with a fast-Fourier-transform algorithm. We present a thorough theoretical analysis of such a device. The realized device is tested by monitoring glucose solutions that induce well defined phase changes between output channels. The simultaneous measurement of three different glucose concentrations shows the multipurpose feature of such devices. The observed errors, caused by the mismatching of spatial frequencies of individual interference patterns with those determined from the CCD camera, are reduced with different reduction schemes. The phase resolution for different pairs of channels was approximately 1 x 10(-4) fringes, which corresponds to a refractive-index resolution of approximately 8.5 x 10(-8). The measured sensitivity coefficient of the phase change versus refractive-index change of approximately 1.22 x 10(3) x 2pi agrees well with the calculated coefficient of approximately 1.20 x 10(3) x 2pi.

Development of a multichannel integrated interferometer immunosensor

This report describes the design, realization and testing of a highly sensitive two-channel integrated optical (IO) Young interferometer (YI) as well as the design of a first multichannel YI. An integrated channel waveguide Y-splitter with two output parallel branches has been used as the basic optical component for building the YI. The generated interference pattern as result of the overlap of outgoing divergent beams is recorded by a CCD camera and is further analyzed by a computer program based on a Fast Fourier Transformation (FFT) algorithm. The integrated waveguide structure is fabricated in SiON technology. For testing the realized device the refractive indices of several glucose solutions have been measured. The realized sensor shows a phase resolution of 1×10−4 fringes corresponding to a refractive index resolution of 2×10−8. The long-term stability is about 1×10−3fringes×h−1 corresponding to a refractive index change of 2×10−7 h−1. The first design of the multichannel YI has four output parallel channels positioned at well-defined distances from each other, such that the phase shift between both channels of one pair can be monitored independently from the other channel pairs.

The segmented waveguide sensor: principle and experiments

A novel type of chemooptical sensor has been designed, fabricated, and characterized. The sensor is simple to fabricate, places low demands on light source quality, and shows a resolution of the chemically induced refractive-index changes better than 5.10/sup -7/.

Drift correction in a multichannel integrated optical young interferometer.

We demonstrate that in a sensor based on a multichannel Young interferometer, the phase information obtained for different pairs of channels can be used to correct the long-term instability (drift) due to temperature differences between measuring and reference channels, the drift in the alignment of the setup, etc. Experiments show that the nature of a major part of the drift is such that the drift present in one of the channels can be determined by interpolation of the drift measured in the two adjacent channels. It is shown that a drift reduction of 10 times can be achieved as compared with the situation in which no correction is applied. We anticipate that these findings will permit the exploitation of the extreme sensitivity of interference-based sensors to a much greater extent.

Building of a Highly Sensitive Two-Channel Integrated Optical Young Interferometer as the First Step Towards Constructing an Integrated Multichannel Interferometer Immunosensor

The integrated chemo-optical evanescent field based sensors offer interested applications in different areas, like in the food industry, medicine, environmental monitoring, bioprocess control, etc. The high sensitivity, selectivity, compactness, and stability, are some of the main attractive features of these sensors. Well known are the IO readout platforms based on interference phenomena, like a Mach-Zehnder interferometer [1], a Young interferometer [2], the Fabry-Perot interferometer [3], and the differential interferometer [4]. Each of these platforms can be provided with an appropriate chemo-optical transduction layer to monitor a certain process, e.g. an immunoreaction, or to measure the concentration of a certain substance present in a given solution. This paper describes the design, the realization and the testing of a highly sensitive two-channel integrated optical Young interferometer, as the first step towards building a multichannel device. The multichannel device we are currently developing will be able to monitor more processes independently and simultaneously. In thus Multichannel Young Interferometer, all pairs of parallel channels act as a two-channel Young interferometer. We will describe the design of the two-channel as well as that of a multichannel Young interferometer. The refractive indices of several glucose solutions have been measured for testing the sensitivity and accuracy of the device. The refractive index resolution of the two-channel Young interferometers as realized up to now is 2×10−8.