Integrated Optical Sensors utilizing Slow-light Propagation in Grated-Waveguide Cavities
01 Jun 2012-
TL;DR: In this article, the authors demonstrate the versatility of a silicon nitride grated waveguide (GWG) optical cavity as a compact IO sensor for bulk-index concentration sensing, label-free protein sensing and mechano-optical gas sensing.
Abstract: Integrated Optical Sensors utilizing Slow-light Propagation in Grated-waveguide Cavities Owing to the small size of integrated optical (IO) devices many basic functions can be integrated on one single IO chip. IO sensors are suitable candidates for accurate detection of small changes of physical or chemical parameters. The integration offers advantages such as enabling a high density of functionalities, automatic and stable alignment of elements, a high potential for mass production with in principle low production costs, and the possibility for the realization of sensor arrays for multi-parameter detection. The main goal of this PhD project is firstly to design, fabricate and demonstrate functioning IO devices based on grated waveguides for sensing applications. A grated waveguide (GWG) is a waveguide with a finite-length grated section, being a structure with a periodic variation of the dielectric constant. Such a structure acts as both a 1-dimensional photonic crystal (PhC) and, owing to modal reflections at the waveguide-GWG transitions, an optical resonator, as evidenced by fringes in the transmission spectrum. In particular near the band edge these fringes can be extremely sharp, which is related to both the near band edge shape of the dispersion curve, corresponding to slow light propagation, and high modal reflectance due to mode mismatch between WG and GWG modes. Both effects lead to strong light-matter interaction, which can be exploited for sensing applications. In this thesis, we demonstrate the versatility of a silicon nitride GWG optical cavity as a compact IO sensor for bulk-index concentration sensing, label-free protein sensing and mechano-optical gas sensing. For concentration sensing, the sensing principle is based on the bulk index change of the GWG top cladding. The principle of the label-free protein sensing relies on the growth and measurement of an ad-layer on the GWG surface, owing to the antigen-antibody interaction. The mechano-optical gas sensing is based on stress-induced deflections of a microcantilever (μCL) suspended above the GWG, which are due to H2 gas absorption by the palladium receptor layer coated on the μCL surface. In the first chapter of this thesis an overview is given of bio- and gas-sensors. In chapter 2, the background of slow light propagation in GWGs and its utilization for sensing applications are discussed. In chapter 3, results related to the first 2 sensing applications (concentration sensing and label-free protein sensing) are presented; here, sensitivity and limit of detection of the sensors are analyzed in detail. The design and fabrication of the GWG-CL integrated readout, and the demonstration of the integrated mechano-optical sensor for gas sensing, are presented in chapter 4 and chapter 5, respectively. Results of an optimization study of the integrated mechano-optical readout principle, on the basis of numerical calculations, is presented in chapter 6. In chapter 7, conclusions and outlook, based on the results presented in this thesis, are given.
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04 Apr 2001
TL;DR: In this paper, a review of the most relevant developments in the field of integrated optical (IO) sensors is presented, where strong and weak points of principle and configuration based on these principles are indicated and main performance data of the IO sensing platforms, especially the obtained resolution, are indicated.
Abstract: During the last decade there has been a rapidly growing interest in integrated optical (IO) sensors, expecially because many of them principally allow for sensitive, real time, label-free-on-site measurements of the concentration of (bio-)chemical species. This review aims at giving an overview of the most relevant developments in this area. After a general introduction into the field of IO sensors for the chemical domain, relevant aspects of integrated optics and chemical sensing are presented in short. A large variety of IO sensing platforms are introduced and discussed: interferometers, resonators, coupling-based devices such as grating couplers and surface plasmon resonance based sensors and finally a new class of sensors based on chemically induced field profile changes. Strong and weak points of principle and of configuration based on these principles are indicated and the main performance data of the IO sensing platforms, especially the obtained resolution, are indicated. Best resolutions of the chemically induced refractive indices on the order of magnitude $10^{-6}-10^{-8}RIU$ can be obtained, corresponding to a resolution of $10^{-3}-10^{-5}$nm in the chemically induced growth of layer thickness of chemo-optical transducer materials. Depending on the anlalyte and the type of transduction layer chemical concentrations down to some ppb or some pg $ml^{-1}$can be determined. Several IO sensing systems are commercially available. Extension of individual sensors to sensor arrays is treated and finally an outlook for the future is given.
215 citations
01 Jun 2011
TL;DR: In this paper, the authors used Bragg-grating cavities inscribed into optical waveguides for label-free sensing of antibody-antigen protein reactions and H2 gas sensing by stress-induced Pd-receptor microcantilever deflections.
Abstract: Use of optical principles for the detection and analysis of biomolecules and biotissue has a long-standing tradition, and highly sensitive optical methods have been developed. Integration on a microchip offers cost reduction and instrument miniaturization, thus enabling novel applications, but also allows reduced biosample volumes, higher sensitivity, and faster acquisition times. We demonstrate optical sensing with Bragg-grating cavities inscribed into optical waveguides for label-free sensing of antibody-antigen protein reactions and H2 gas sensing by stress-induced Pd-receptor microcantilever deflections. Furthermore, we introduce the method of modulation-frequency-encoded multi-wavelength fluorescent DNA analysis in an optofluidic chip during capillary electrophoresis separation, enabling detection down to the single-molecule level and allowing simultaneous analysis of DNA fragments from independent human genomic segments, associated with genetic predispositions to breast cancer and anemia, in a single experiment. Finally, by integrating wavelength-selective arrayed-waveguide gratings on a microchip, we demonstrate on-chip Raman spectroscopy and spectral-domain optical coherence tomography of biotissue.
3 citations
01 Aug 2009
TL;DR: In this article, the 2D bidirectional eigenmode propagation (BEP) method has been applied to analyze the effect of cantilever displacement on the optical transmission spectrum of the Si3N4 grated waveguide (GWG).
Abstract: We present results related to the simulation and fabrication of a novel and highly sensitive mechano-optical sensor for gas detection (i.e., hydrogen gas) based on microcantilevers, supplied with a selective gas absorption layer, suspended above a Si3N4 grated waveguide (GWG). The presence of a dielectric object, in this case a suspended cantilever, in the evanescent field region of the GWG may lead to the occurrence of propagating modes for wavelengths inside the stop band of the grating, and so to defect modes inside the stop band. These modes introduce sharp features in the transmission spectrum of the device. These features are quite suitable to monitor stress induced bending of the cantilever owing to concentration changes of the gas for which the absorptive layer is sensitive.
The 2D bidirectional eigenmode propagation (BEP) method has been applied to analyze the effect of cantilever displacement on the optical transmission spectrum of the GWG. The simulation results show that as the cantilever approaches the grating, the first near band-edge resonance peak is pulled inside the stop band and its spectral width decreases. The resolution of displacement measurement is estimated to be 0.2 nm for a 200 nm thick cantilever at a 200 nm initial gap, assuming a signal-to-noise ratio (SNR) of 20 dB.
Integrated microcantilever-GWG devices have been fabricated successfully using MEMS techniques. Uniform gratings have been defined with laser interference lithography. SiO2 cantilevers with low initial bending (i.e., low stress) have been fabricated by combining the tetra-ethyl-ortho-silicate chemical vapor deposition (TEOS-CVD) and plasma-enhanced chemical vapor deposition (PE-CVD) oxides, and by releasing them using a tetramethylammonium hydroxide (TMAH) wet-etching solution to remove the sacrificial poly-Si layer, followed by a freeze-drying process. Currently we are optimizing the fabrication process to achieve cantilevers with low initial bending. Detailed results, also discussing the potential of the integrated microcantilever-GWG as a novel and compact mechano-optical sensor for hydrogen gas, will be presented during the conference.
2 citations
01 Oct 1990
TL;DR: In this paper, surface plasmon resonance is applied for sensing concentrations of ammonia in air, using a thin bromo-cresol purple layer as a chemo-optical interface.
Abstract: Surface plasmon resonance is applied for sensing concentrations of ammonia in air, using a thin bromo-cresol purple layer as a chemo-optical interface. The sensor shows a dynamic range of 0.5–15 mbar, a resolution of about 5% and a response time smaller than 1 min.
2 citations
27 Nov 2009
TL;DR: In this article, the authors presented results related to the fabrication of a novel and highly sensitive mechano-optical sensor for hydrogen gas, based on microcantilevers, supplied with a selective gas absorbing layer (Pd), suspended above a Si3N4 grated waveguide (GWG).
Abstract: We present results related to the fabrication of a novel and highly sensitive mechano-optical sensor for hydrogen gas, based on microcantilevers, supplied with a selective gas absorbing layer (Pd), suspended above a Si3N4 grated waveguide (GWG). Integrated microcantilever-GWG devices have been fabricated
successfully using MEMS techniques. Several technical problems encountered during the preparation of such integrated devices (i.e., grating production, surface roughness, facet quality) will be discussed and solutions to address these issues will be given as well.
2 citations
References
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Book•
03 Jul 1995
TL;DR: In this paper, the authors developed the theoretical tools of photonics using principles of linear algebra and symmetry, emphasizing analogies with traditional solid-state physics and quantum theory, and investigated the unique phenomena that take place within photonic crystals at defect sites and surfaces, from one to three dimensions.
Abstract: Since it was first published in 1995, Photonic Crystals has remained the definitive text for both undergraduates and researchers on photonic band-gap materials and their use in controlling the propagation of light. This newly expanded and revised edition covers the latest developments in the field, providing the most up-to-date, concise, and comprehensive book available on these novel materials and their applications. Starting from Maxwell's equations and Fourier analysis, the authors develop the theoretical tools of photonics using principles of linear algebra and symmetry, emphasizing analogies with traditional solid-state physics and quantum theory. They then investigate the unique phenomena that take place within photonic crystals at defect sites and surfaces, from one to three dimensions. This new edition includes entirely new chapters describing important hybrid structures that use band gaps or periodicity only in some directions: periodic waveguides, photonic-crystal slabs, and photonic-crystal fibers. The authors demonstrate how the capabilities of photonic crystals to localize light can be put to work in devices such as filters and splitters. A new appendix provides an overview of computational methods for electromagnetism. Existing chapters have been considerably updated and expanded to include many new three-dimensional photonic crystals, an extensive tutorial on device design using temporal coupled-mode theory, discussions of diffraction and refraction at crystal interfaces, and more. Richly illustrated and accessibly written, Photonic Crystals is an indispensable resource for students and researchers.Extensively revised and expanded Features improved graphics throughout Includes new chapters on photonic-crystal fibers and combined index-and band-gap-guiding Provides an introduction to coupled-mode theory as a powerful tool for device design Covers many new topics, including omnidirectional reflection, anomalous refraction and diffraction, computational photonics, and much more.
8,188 citations
TL;DR: Main application areas are outlined and examples of applications of SPR sensor technology are presented and future prospects of SPR technology are discussed.
Abstract: Since the first application of the surface plasmon resonance (SPR) phenomenon for sensing almost two decades ago, this method has made great strides both in terms of instrumentation development and applications. SPR sensor technology has been commercialized and SPR biosensors have become a central tool for characterizing and quantifying biomolecular interactions. This paper attempts to review the major developments in SPR technology. Main application areas are outlined and examples of applications of SPR sensor technology are presented. Future prospects of SPR sensor technology are discussed.
5,127 citations
TL;DR: In this paper, an experimental demonstration of electromagnetically induced transparency in an ultracold gas of sodium atoms, in which the optical pulses propagate at twenty million times slower than the speed of light in a vacuum, is presented.
Abstract: Techniques that use quantum interference effects are being actively investigated to manipulate the optical properties of quantum systems1. One such example is electromagnetically induced transparency, a quantum effect that permits the propagation of light pulses through an otherwise opaque medium2,3,4,5. Here we report an experimental demonstration of electromagnetically induced transparency in an ultracold gas of sodium atoms, in which the optical pulses propagate at twenty million times slower than the speed of light in a vacuum. The gas is cooled to nanokelvin temperatures by laser and evaporative cooling6,7,8,9,10. The quantum interference controlling the optical properties of the medium is set up by a ‘coupling’ laser beam propagating at a right angle to the pulsed ‘probe’ beam. At nanokelvin temperatures, the variation of refractive index with probe frequency can be made very steep. In conjunction with the high atomic density, this results in the exceptionally low light speeds observed. By cooling the cloud below the transition temperature for Bose–Einstein condensation11,12,13 (causing a macroscopic population of alkali atoms in the quantum ground state of the confining potential), we observe even lower pulse propagation velocities (17?m?s−1) owing to the increased atom density. We report an inferred nonlinear refractive index of 0.18?cm2?W−1 and find that the system shows exceptionally large optical nonlinearities, which are of potential fundamental and technological interest for quantum optics.
3,438 citations
06 Jun 2003
TL;DR: This work demonstrates a process for producing silica toroid-shaped microresonators-on-a-chip with Q factors in excess of 100 million using a combination of lithography, dry etching and a selective reflow process, representing an improvement of nearly four orders of magnitude over previous chip-based resonators.
Abstract: We demonstrate microfabrication of ultra-high-Q microcavities on a chip, exhibiting a novel toroid-shaped geometry. The cavities possess Q-factors in excess of 100 million which constitutes an improvement close to 4 orders-of-magnitude in Q compared to previous work [B. Gayral, et al., 1999].
2,177 citations
"Integrated Optical Sensors utilizin..." refers background in this paper
...…of Twente The research described in this thesis was carried out at the Integrated Optical MicroSystems (IOMS) Group, Faculty of Electrical Engineering, Mathematics and Computer Science, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands....
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TL;DR: This article reviews the recent progress in optical biosensors that use the label-free detection protocol, in which biomolecules are unlabeled or unmodified, and are detected in their natural forms, and focuses on the optical biosENSors that utilize the refractive index change as the sensing transduction signal.
2,060 citations