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848 KiB

Open AccessArticle

A Refractive Index Sensor Based on a Metal-Insulator-Metal Waveguide-Coupled Ring Resonator

by Shu-Bin Yan, Liang Luo, Chen-Yang Xue and Zhi-Dong Zhang

Sensors 2015, 15(11), 29183-29191; https://doi.org/10.3390/s151129183 - 19 Nov 2015

Cited by 58 | Viewed by 7814

Abstract

A refractive index sensor composed of two straight metal-insulator-metal waveguides and a ring resonator is presented. One end of each straight waveguide is sealed and the other end acts as port. The transmission spectrum and magnetic field distribution of this sensor structure are [...] Read more.

A refractive index sensor composed of two straight metal-insulator-metal waveguides and a ring resonator is presented. One end of each straight waveguide is sealed and the other end acts as port. The transmission spectrum and magnetic field distribution of this sensor structure are simulated using finite-difference time-domain method (FDTD). The results show that an asymmetric line shape is observed in the transmission spectrum, and that the transmission spectrum shows a filter-like behavior. The quality factor and sensitivity are taken to characterize its sensing performance and filter properties. How structural parameters affect the sensing performance and filter properties is also studied. Full article

(This article belongs to the Special Issue Silicon Based Optical Sensors)

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1152 KiB

Open AccessArticle

A Long Distance Phase-Sensitive Optical Time Domain Reflectometer with Simple Structure and High Locating Accuracy

by Yi Shi, Hao Feng and Zhoumo Zeng

Sensors 2015, 15(9), 21957-21970; https://doi.org/10.3390/s150921957 - 2 Sep 2015

Cited by 46 | Viewed by 7685

Abstract

A phase-sensitive optical time domain reflectometer (Φ-OTDR) can be used for pipeline security. However, the sensing distance (less than 20 km) of traditional Φ-OTDR is too short for the needs of typical oil and gas pipeline monitoring applications (30–50 km). A simple structure [...] Read more.

A phase-sensitive optical time domain reflectometer (Φ-OTDR) can be used for pipeline security. However, the sensing distance (less than 20 km) of traditional Φ-OTDR is too short for the needs of typical oil and gas pipeline monitoring applications (30–50 km). A simple structure Φ-OTDR system utilizing long pulse, balanced amplified detector and heterodyne detection is proposed in this paper and the sensing range is thereby increased to 60 km. Through analyzing the sensing principle of Φ-OTDR, a novel locating strategy is proposed to maintain the locating accuracy at a few meters when a long pulse (5 µs) is used. The increased pulse width deteriorates the time series of each sensing point seriously. In order to eliminate the deterioration, a data processing technique combining wavelet and empirical mode decomposition is applied in this system. The experiment results show that the sensing distance can be increased to 60 km and the locating accuracy is maintained at 6.8 m. Full article

(This article belongs to the Special Issue Silicon Based Optical Sensors)

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1194 KiB

Open AccessArticle

A Ratiometric Wavelength Measurement Based on a Silicon-on-Insulator Directional Coupler Integrated Device

by Pengfei Wang, Agus Muhamad Hatta, Haoyu Zhao, Jie Zheng, Gerald Farrell and Gilberto Brambilla

Sensors 2015, 15(9), 21280-21293; https://doi.org/10.3390/s150921280 - 28 Aug 2015

Cited by 5 | Viewed by 7274

Abstract

A ratiometric wavelength measurement based on a Silicon-on-Insulator (SOI) integrated device is proposed and designed, which consists of directional couplers acting as two edge filters with opposite spectral responses. The optimal separation distance between two parallel silicon waveguides and the interaction length of [...] Read more.

A ratiometric wavelength measurement based on a Silicon-on-Insulator (SOI) integrated device is proposed and designed, which consists of directional couplers acting as two edge filters with opposite spectral responses. The optimal separation distance between two parallel silicon waveguides and the interaction length of the directional coupler are designed to meet the desired spectral response by using local supermodes. The wavelength discrimination ability of the designed ratiometric structure is demonstrated by a beam propagation method numerically and then is verified experimentally. The experimental results have shown a general agreement with the theoretical models. The ratiometric wavelength system demonstrates a resolution of better than 50 pm at a wavelength around 1550 nm with ease of assembly and calibration. Full article

(This article belongs to the Special Issue Silicon Based Optical Sensors)

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1614 KiB

Open AccessArticle

The Thermoluminescence Response of Ge-Doped Flat Fibers to Gamma Radiation

by Siti Nurasiah Binti Mat Nawi, Nor Fadira Binti Wahib, Nurul Najua Binti Zulkepely, Yusoff Bin Mohd Amin, Ung Ngie Min, David Andrew Bradley, Roslan Bin Md Nor and Mohd Jamil Maah

Sensors 2015, 15(8), 20557-20569; https://doi.org/10.3390/s150820557 - 20 Aug 2015

Cited by 19 | Viewed by 5632

Abstract

Study has been undertaken of the thermoluminescence (TL) yield of various tailor-made flat cross-section 6 mol% Ge-doped silica fibers, differing only in respect of external dimensions. Key TL dosimetric characteristics have been investigated, including glow curves, dose response, sensitivity, fading and reproducibility. Using [...] Read more.

Study has been undertaken of the thermoluminescence (TL) yield of various tailor-made flat cross-section 6 mol% Ge-doped silica fibers, differing only in respect of external dimensions. Key TL dosimetric characteristics have been investigated, including glow curves, dose response, sensitivity, fading and reproducibility. Using a ⁶⁰Co source, the samples were irradiated to doses within the range 1 to 10 Gy. Prior to irradiation, the flat fibers were sectioned into 6 mm lengths, weighed, and annealed at 400 °C for 1 h. TL readout was by means of a Harshaw Model 3500 TLD reader, with TLD-100 chips (LiF:Mg, Ti) used as a reference dosimeter to allow the relative response of the fibers to be evaluated. The fibers have been found to provide highly linear dose response and excellent reproducibility over the range of doses investigated, demonstrating high potential as TL-mode detectors in radiation medicine applications. Mass for mass, the results show the greatest TL yield to be provided by fibers of the smallest cross-section, analysis indicating this to be due to minimal light loss in transport of the TL through the bulk of the silica medium. Full article

(This article belongs to the Special Issue Silicon Based Optical Sensors)

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1670 KiB

Open AccessArticle

Integrated High Resolution Digital Color Light Sensor in 130 nm CMOS Technology

by Drago Strle, Uroš Nahtigal, Graciele Batistell, Vincent Chi Zhang, Erwin Ofner, Andrea Fant and Johannes Sturm

Sensors 2015, 15(7), 17786-17807; https://doi.org/10.3390/s150717786 - 22 Jul 2015

Cited by 6 | Viewed by 8218

Abstract

This article presents a color light detection system integrated in 130 nm CMOS technology. The sensors and corresponding electronics detect light in a CIE XYZ color luminosity space using on-chip integrated sensors without any additional process steps, high-resolution analog-to-digital converter, and dedicated DSP [...] Read more.

This article presents a color light detection system integrated in 130 nm CMOS technology. The sensors and corresponding electronics detect light in a CIE XYZ color luminosity space using on-chip integrated sensors without any additional process steps, high-resolution analog-to-digital converter, and dedicated DSP algorithm. The sensor consists of a set of laterally arranged integrated photodiodes that are partly covered by metal, where color separation between the photodiodes is achieved by lateral carrier diffusion together with wavelength-dependent absorption. A high resolution, hybrid, ∑∆ ADC converts each photo diode’s current into a 22-bit digital result, canceling the dark current of the photo diodes. The digital results are further processed by the DSP, which calculates normalized XYZ or RGB color and intensity parameters using linear transformations of the three photo diode responses by multiplication of the data with a transformation matrix, where the coefficients are extracted by training in combination with a pseudo-inverse operation and the least-mean square approximation. The sensor system detects the color light parameters with 22-bit accuracy, consumes less than 60 μA on average at 10 readings per second, and occupies approx. 0.8 mm²of silicon area (including three photodiodes and the analog part of the ADC). The DSP is currently implemented on FPGA. Full article

(This article belongs to the Special Issue Silicon Based Optical Sensors)

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1818 KiB

Open AccessArticle

Design of a High-Performance Micro Integrated Surface Plasmon Resonance Sensor Based on Silicon-On-Insulator Rib Waveguide Array

by Dengpeng Yuan, Ying Dong, Yujin Liu and Tianjian Li

Sensors 2015, 15(7), 17313-17328; https://doi.org/10.3390/s150717313 - 16 Jul 2015

Cited by 19 | Viewed by 7014

Abstract

Based on silicon-on-insulator (SOI) rib waveguide with large cross-section, a micro integrated surface plasmon resonance (SPR) biochemical sensor platform is proposed. SPR is excited at the deeply etched facet of the bend waveguide by the guiding mode and a bimetallic configuration is employed. [...] Read more.

Based on silicon-on-insulator (SOI) rib waveguide with large cross-section, a micro integrated surface plasmon resonance (SPR) biochemical sensor platform is proposed. SPR is excited at the deeply etched facet of the bend waveguide by the guiding mode and a bimetallic configuration is employed. With the advantages of SOI rib waveguide and the silicon microfabrication technology, an array of the SPR sensors can be composed to implement wavelength interrogation of the sensors’ output signal, so the spectrometer or other bulky and expensive equipment are not necessary, which enables the SPR sensor to realize the miniaturization and integration of the entire sensing system. The performances of the SPR sensor element are verified by using the two-dimensional finite-different time-domain method. The parameters of the sensor element and the array are optimized for the achievement of high performance for biochemical sensing application. As a typical example, a single bimetallic SPR sensor with 3 nm Au over 32 nm Al possesses a high sensitivity of 3.968 × 10⁴ nm/RIU, a detection-accuracy of 14.7 μm⁻¹. For a uniparted SPR sensor, it can achieve a detection limit of 5.04 × 10⁻⁷ RIU. With the relative power measurement accuracy of 0.01 dB, the refractive index variation of 1.14 × 10⁻⁵ RIU can be detected by the SPR sensor array. Full article

(This article belongs to the Special Issue Silicon Based Optical Sensors)

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2358 KiB

Open AccessArticle

Design and Optimization of SiON Ring Resonator-Based Biosensors for Aflatoxin M1 Detection

by Romain Guider, Davide Gandolfi, Tatevik Chalyan, Laura Pasquardini, Alina Samusenko, Georg Pucker, Cecilia Pederzolli and Lorenzo Pavesi

Sensors 2015, 15(7), 17300-17312; https://doi.org/10.3390/s150717300 - 16 Jul 2015

Cited by 44 | Viewed by 7778

Abstract

In this article, we designed and studied silicon oxynitride (SiON) microring-based photonic structures for biosensing applications. We designed waveguides, directional couplers, and racetrack resonators in order to measure refractive index changes smaller than 10⁻⁶ refractive index units (RIU). We tested various samples [...] Read more.

In this article, we designed and studied silicon oxynitride (SiON) microring-based photonic structures for biosensing applications. We designed waveguides, directional couplers, and racetrack resonators in order to measure refractive index changes smaller than 10⁻⁶ refractive index units (RIU). We tested various samples with different SiON refractive indexes as well as the waveguide dimensions for selecting the sensor with the best performance. Propagation losses and bending losses have been measured on test structures, along with a complete characterization of the resonator’s performances. Sensitivities and limit of detection (LOD) were also measured using glucose-water solutions and compared with expected results from simulations. Finally, we functionalized the resonator and performed sensing experiments with Aflatoxin M1 (AFM1). We were able to detect the binding of aflatoxin for concentrations as low as 12.5 nm. The results open up the path for designing cost-effective biosensors for a fast and reliable sensitive analysis of AFM1 in milk. Full article

(This article belongs to the Special Issue Silicon Based Optical Sensors)

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4827 KiB

Open AccessArticle

Recognition of a Phase-Sensitivity OTDR Sensing System Based on Morphologic Feature Extraction

by Qian Sun, Hao Feng, Xueying Yan and Zhoumo Zeng

Sensors 2015, 15(7), 15179-15197; https://doi.org/10.3390/s150715179 - 29 Jun 2015

Cited by 127 | Viewed by 9043

Abstract

This paper proposes a novel feature extraction method for intrusion event recognition within a phase-sensitive optical time-domain reflectometer (Φ-OTDR) sensing system. Feature extraction of time domain signals in these systems is time-consuming and may lead to inaccuracies due to noise disturbances. The recognition [...] Read more.

This paper proposes a novel feature extraction method for intrusion event recognition within a phase-sensitive optical time-domain reflectometer (Φ-OTDR) sensing system. Feature extraction of time domain signals in these systems is time-consuming and may lead to inaccuracies due to noise disturbances. The recognition accuracy and speed of current systems cannot meet the requirements of Φ-OTDR online vibration monitoring systems. In the method proposed in this paper, the time-space domain signal is used for feature extraction instead of the time domain signal. Feature vectors are obtained from morphologic features of time-space domain signals. A scatter matrix is calculated for the feature selection. Experiments show that the feature extraction method proposed in this paper can greatly improve recognition accuracies, with a lower computation time than traditional methods, i.e., a recognition accuracy of 97.8% can be achieved with a recognition time of below 1 s, making it is very suitable for Φ-OTDR system online vibration monitoring. Full article

(This article belongs to the Special Issue Silicon Based Optical Sensors)

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2090 KiB

Open AccessArticle

Design Procedure and Fabrication of Reproducible Silicon Vernier Devices for High-Performance Refractive Index Sensing

by Benedetto Troia, Ali Z. Khokhar, Milos Nedeljkovic, Scott A. Reynolds, Youfang Hu, Goran Z. Mashanovich and Vittorio M. N. Passaro

Sensors 2015, 15(6), 13548-13567; https://doi.org/10.3390/s150613548 - 10 Jun 2015

Cited by 15 | Viewed by 6570

Abstract

In this paper, we propose a generalized procedure for the design of integrated Vernier devices for high performance chemical and biochemical sensing. In particular, we demonstrate the accurate control of the most critical design and fabrication parameters of silicon-on-insulator cascade-coupled racetrack resonators operating [...] Read more.

In this paper, we propose a generalized procedure for the design of integrated Vernier devices for high performance chemical and biochemical sensing. In particular, we demonstrate the accurate control of the most critical design and fabrication parameters of silicon-on-insulator cascade-coupled racetrack resonators operating in the second regime of the Vernier effect, around 1.55 μm. The experimental implementation of our design strategies has allowed a rigorous and reliable investigation of the influence of racetrack resonator and directional coupler dimensions as well as of waveguide process variability on the operation of Vernier devices. Figures of merit of our Vernier architectures have been measured experimentally, evidencing a high reproducibility and a very good agreement with the theoretical predictions, as also confirmed by relative errors even lower than 1%. Finally, a Vernier gain as high as 30.3, average insertion loss of 2.1 dB and extinction ratio up to 30 dB have been achieved. Full article

(This article belongs to the Special Issue Silicon Based Optical Sensors)

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1354 KiB

Open AccessArticle

Thermodynamic Modeling and Analysis of an Optical Electric-Field Sensor

by Xia Xiao, Yan Xu and Zexing Dong

Sensors 2015, 15(4), 7125-7135; https://doi.org/10.3390/s150407125 - 24 Mar 2015

Cited by 21 | Viewed by 5736

Abstract

The stability of the optical electric field sensor (OEFS) in actual operation is affected by environmental factors such as temperature and SF₆ (sulfur hexafluoride). To analyze the operational environment parameters affecting the optical properties of crystals, a thermodynamic model of the OEFS [...] Read more.

The stability of the optical electric field sensor (OEFS) in actual operation is affected by environmental factors such as temperature and SF₆ (sulfur hexafluoride). To analyze the operational environment parameters affecting the optical properties of crystals, a thermodynamic model of the OEFS in which the optical properties of the crystal are changed by the first-order effects and the second-order effects was established. The intensity parameters such as electric, stress and temperature fields were introduced. The theoretical analysis results show that under temperature, stress and electric field conditions, the optical properties of the sensing crystals are no longer changed only by the electro-optic effect, but also by the temperature and the stress fields. Further synthesis suggests the expected optical property changes under the effect of the environment fields. OEFS tests show that the accuracy of OEFS is dependent on temperature with a ratio error of −0.8%~1.5% in the temperature range from −25 °C to +40 °C. Full article

(This article belongs to the Special Issue Silicon Based Optical Sensors)

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407 KiB

Open AccessArticle

Distance Measurement Error in Time-of-Flight Sensors Due to Shot Noise

by Julio Illade-Quinteiro, Víctor M. Brea, Paula López, Diego Cabello and Gines Doménech-Asensi

Sensors 2015, 15(3), 4624-4642; https://doi.org/10.3390/s150304624 - 25 Feb 2015

Cited by 34 | Viewed by 8289

Abstract

Unlike other noise sources, which can be reduced or eliminated by different signal processing techniques, shot noise is an ever-present noise component in any imaging system. In this paper, we present an in-depth study of the impact of shot noise on time-of-flight sensors [...] Read more.

Unlike other noise sources, which can be reduced or eliminated by different signal processing techniques, shot noise is an ever-present noise component in any imaging system. In this paper, we present an in-depth study of the impact of shot noise on time-of-flight sensors in terms of the error introduced in the distance estimation. The paper addresses the effect of parameters, such as the size of the photosensor, the background and signal power or the integration time, and the resulting design trade-offs. The study is demonstrated with different numerical examples, which show that, in general, the phase shift determination technique with two background measurements approach is the most suitable for pixel arrays of large resolution. Full article

(This article belongs to the Special Issue Silicon Based Optical Sensors)

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2292 KiB

Open AccessReview

Porous Silicon Structures as Optical Gas Sensors

by Igor A. Levitsky

Sensors 2015, 15(8), 19968-19991; https://doi.org/10.3390/s150819968 - 14 Aug 2015

Cited by 106 | Viewed by 10118

Abstract

We present a short review of recent progress in the field of optical gas sensors based on porous silicon (PSi) and PSi composites, which are separate from PSi optochemical and biological sensors for a liquid medium. Different periodical and nonperiodical PSi photonic structures [...] Read more.

We present a short review of recent progress in the field of optical gas sensors based on porous silicon (PSi) and PSi composites, which are separate from PSi optochemical and biological sensors for a liquid medium. Different periodical and nonperiodical PSi photonic structures (bares, modified by functional groups or infiltrated with sensory polymers) are described for gas sensing with an emphasis on the device specificity, sensitivity and stability to the environment. Special attention is paid to multiparametric sensing and sensor array platforms as effective trends for the improvement of analyte classification and quantification. Mechanisms of gas physical and chemical sorption inside PSi mesopores and pores of PSi functional composites are discussed. Full article

(This article belongs to the Special Issue Silicon Based Optical Sensors)

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1178 KiB

Open AccessReview

Optical Fibre Pressure Sensors in Medical Applications

by Sven Poeggel, Daniele Tosi, DineshBabu Duraibabu, Gabriel Leen, Deirdre McGrath and Elfed Lewis

Sensors 2015, 15(7), 17115-17148; https://doi.org/10.3390/s150717115 - 15 Jul 2015

Cited by 172 | Viewed by 23136

Abstract

This article is focused on reviewing the current state-of-the-art of optical fibre pressure sensors for medical applications. Optical fibres have inherent advantages due to their small size, immunity to electromagnetic interferences and their suitability for remote monitoring and multiplexing. The small dimensions of [...] Read more.

This article is focused on reviewing the current state-of-the-art of optical fibre pressure sensors for medical applications. Optical fibres have inherent advantages due to their small size, immunity to electromagnetic interferences and their suitability for remote monitoring and multiplexing. The small dimensions of optical fibre-based pressure sensors, together with being lightweight and flexible, mean that they are minimally invasive for many medical applications and, thus, particularly suited to in vivo measurement. This means that the sensor can be placed directly inside a patient, e.g., for urodynamic and cardiovascular assessment. This paper presents an overview of the recent developments in optical fibre-based pressure measurements with particular reference to these application areas. Full article

(This article belongs to the Special Issue Silicon Based Optical Sensors)

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