Fiber‐optic device acting as a high‐accuracy wide‐range variable optical attenuator

1990 ◽  
Vol 61 (9) ◽  
pp. 2476-2477
Author(s):  
Mikio Yamashita
Keyword(s):  
Fiber Optic ◽  
High Accuracy ◽  
Variable Optical Attenuator ◽  
Wide Range

scholarly journals A Novel Ultrasonic TOF Ranging System Using AlN Based PMUTs

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 284
Author(s):  
Yihsiang Chiu ◽  
Chen Wang ◽  
Dan Gong ◽  
Nan Li ◽  
Shenglin Ma ◽  
...  
Keyword(s):  
Clock Cycle ◽  
High Accuracy ◽  
Ultrasonic Waves ◽  
Oxide Semiconductor ◽  
Average Error ◽  
Cmos Process ◽  
Clock Frequency ◽  
Time Frequency ◽  
Range Finding ◽  
Wide Range

This paper presents a high-accuracy complementary metal oxide semiconductor (CMOS) driven ultrasonic ranging system based on air coupled aluminum nitride (AlN) based piezoelectric micromachined ultrasonic transducers (PMUTs) using time of flight (TOF). The mode shape and the time-frequency characteristics of PMUTs are simulated and analyzed. Two pieces of PMUTs with a frequency of 97 kHz and 96 kHz are applied. One is used to transmit and the other is used to receive ultrasonic waves. The Time to Digital Converter circuit (TDC), correlating the clock frequency with sound velocity, is utilized for range finding via TOF calculated from the system clock cycle. An application specific integrated circuit (ASIC) chip is designed and fabricated on a 0.18 μm CMOS process to acquire data from the PMUT. Compared to state of the art, the developed ranging system features a wide range and high accuracy, which allows to measure the range of 50 cm with an average error of 0.63 mm. AlN based PMUT is a promising candidate for an integrated portable ranging system.

scholarly journals Novel Bloch wave excitation platform based on few-layer photonic crystal deposited on D-shaped optical fiber

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Esteban Gonzalez-Valencia ◽  
Ignacio Del Villar ◽  
Pedro Torres
Keyword(s):  
Optical Fibers ◽  
High Performance ◽  
Light Propagation ◽  
Fiber Optic ◽  
Layer Structure ◽  
Optical Network ◽  
Building Blocks ◽  
Bloch Wave ◽  
Nanophotonic Devices ◽  
Wide Range

AbstractWith the goal of ultimate control over the light propagation, photonic crystals currently represent the primary building blocks for novel nanophotonic devices. Bloch surface waves (BSWs) in periodic dielectric multilayer structures with a surface defect is a well-known phenomenon, which implies new opportunities for controlling the light propagation and has many applications in the physical and biological science. However, most of the reported structures based on BSWs require depositing a large number of alternating layers or exploiting a large refractive index (RI) contrast between the materials constituting the multilayer structure, thereby increasing the complexity and costs of manufacturing. The combination of fiber–optic-based platforms with nanotechnology is opening the opportunity for the development of high-performance photonic devices that enhance the light-matter interaction in a strong way compared to other optical platforms. Here, we report a BSW-supporting platform that uses geometrically modified commercial optical fibers such as D-shaped optical fibers, where a few-layer structure is deposited on its flat surface using metal oxides with a moderate difference in RI. In this novel fiber optic platform, BSWs are excited through the evanescent field of the core-guided fundamental mode, which indicates that the structure proposed here can be used as a sensing probe, along with other intrinsic properties of fiber optic sensors, as lightness, multiplexing capacity and easiness of integration in an optical network. As a demonstration, fiber optic BSW excitation is shown to be suitable for measuring RI variations. The designed structure is easy to manufacture and could be adapted to a wide range of applications in the fields of telecommunications, environment, health, and material characterization.

scholarly journals Fiber Optic Attenuator

2021 ◽  
Vol 2086 (1) ◽  
pp. 012128
Author(s):  
D P Andreev ◽  
E I Andreeva
Keyword(s):  
Optical Fiber ◽  
Spectral Dependence ◽  
Fiber Optic ◽  
Dynamic Range ◽  
Wide Range ◽  
Bending Losses ◽  
Type Fiber

Abstract A study of a bending-type fiber-optic attenuator has been carried out. It is shown that the use of G.655 - optical fiber provides the largest dynamic range of the attenuator. The spectral dependence of the bending losses was measured in a wide range of wavelengths: from 1270 to 1610 nm.

A variety of surface waves in ocean-bottom DAS records

2021 ◽  
Author(s):  
Zack Spica ◽  
Loïc Viens ◽  
Jorge Castillo Castellanos ◽  
Takeshi Akuhara ◽  
Kiwamu Nishida ◽  
...  
Keyword(s):  
Surface Wave ◽  
Acoustic Waves ◽  
Fiber Optic ◽  
Acoustic Noise ◽  
Seismic Exploration ◽  
Ocean Bottom ◽  
Wide Range ◽  
Ocean Layer ◽  
Noise Cross Correlation ◽  
Low Amplitude

<p>Distributed acoustic sensing (DAS) can transform existing telecommunication fiber-optic cables into arrays of thousands of sensors, enabling meter-scale recordings over tens of kilometers. Recently, DAS has demonstrated its utility for many seismological applications onshore. However, the use of offshore cables for seismic exploration and monitoring is still in its infancy.<br>In this work, we introduce some new results and observations obtained from a fiber-optic cable offshore the coast of Sanriku, Japan. In particular, we focus on surface wave retrieved from various signals and show that ocean-bottom DAS can be used to extract dispersion curves (DC) over a wide range of frequencies. We show that multi-mode DC can be easily extracted from ambient seismo-acoustic noise cross-correlation functions or F-K analysis. Moderate magnitude earthquakes also contain multiple surface-wave packets that are buried within their coda. Fully-coupled 3-D numerical simulations suggest that these low-amplitude signals originate from the continuous reverberations of the acoustic waves in the ocean layer. </p>

Finding Gene Names

2006 ◽  
Author(s):  
Soumya Raychaudhuri
Keyword(s):  
Natural Language Processing ◽  
Language Processing ◽  
Critical Issue ◽  
High Accuracy ◽  
Scientific Text ◽  
Recognition Algorithms ◽  
Wide Range ◽  
Genomics Research ◽  
Processing Techniques ◽  
Mining Algorithms

Successful use of text mining algorithms to facilitate genomics research hinges on the ability to recognize the names of genes in scientific text. In this chapter we address the critical issue of gene name recognition. Once gene names can be recognized in the scientific text, we can begin to understand what the text says about those genes. This is a much more challenging issue than one might appreciate at first glance. Gene names can be inconsistent and confusing; automated gene name recognition efforts have therfore turned out to be quite challenging to implement with high accuracy. Gene name recognition algorithms have a wide range of useful applications. Until this chapter we have been avoiding this issue and have been using only gene-article indices. In practice these indices are manually assembled. Gene name recognition algorithms offer the possibility of automating and expediting the laborious task of building reference indices. Article indices can be built that associate articles to genes based on whether or not the article mentions the gene by name. In addition, gene name recognition is the first step in doing more detailed sentence-by-sentence text analysis. For example, in Chapter 10 we will talk about identifying relationships between genes from text. Frequently, this requires identifying sentences refering to two gene names, and understanding what sort of relationship the sentence is describing between these genes. Sophisticated natural language processing techniques to parse sentences and understand gene function cannot be done in a meaningful way without recognizing where the gene names are in the first place. The major concepts of this chapter are presented in the frame box. We begin by describing the commonly used strategies that can be used alone or in concert to identify gene names. At the end of the chapter we introduce one successful name finding algorithm that combines many of the different strategies. There are several commonly used approaches that can be exploited to recognize gene names in text (Chang, Shutze, et al. 2004). Often times these approaches can be combined into even more effective multifaceted algorithms.

scholarly journals Direct detection of charge and discharge process in supercapacitor by fiber-optic LSPR sensors

Nanophotonics ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 1071-1079 ◽  
Author(s):  
Siyu Qian ◽  
Xinlong Chen ◽  
Shiyu Jiang ◽  
Qiwen Pan ◽  
Yachen Gao ◽  
...  
Keyword(s):  
Fiber Optic ◽  
Direct Detection ◽  
Low Cost ◽  
The State ◽  
State Of Charge ◽  
Localized Surface Plasmon ◽  
High Price ◽  
Discharge Process ◽  
Practical Applications ◽  
Wide Range

AbstractSupercapacitors with high power density, ultralong lifespan and wide range operating temperature have drawn significant attention in recent years. However, monitoring the state of charge in supercapacitors in a cost-effective and flexible way is still challenging. Techniques such as transmission electron microscopy and X-ray diffraction can analyze the characteristics of supercapacitor well. But with large size and high price, they are not suitable for daily monitoring of the supercapacitors’ operation. In this paper, a low cost and easily fabricated fiber-optic localized surface plasmon resonance (LSPR) probe is proposed to monitor the state of charge of the electrode in a supercapacitor. The Au nanoparticles were loading on the fiber core as LSPR sensing region. In order to implant the fiber in the supercapacitor, a reflective type of fiber sensor was used. The results show that this tiny fiber-optic LSPR sensor can provide online monitoring of the state of charge during the charging and discharging process in situ. The intensity shift in LSPR sensor has a good linear relationship with the state of charge calculated by standard galvanostatic charging and discharging test. In addition, this LSPR sensor is insensitive to the temperature change, presenting a great potential in practical applications.

A fractional order model for electrochemical impedance of IPMC actuators based on constant phase element

2020 ◽  
pp. 1045389X2097443
Author(s):  
Mohammad Javad Doregiraei ◽  
Hossein Moeinkhah ◽  
Jafar Sadeghi
Keyword(s):  
Fractional Order ◽  
Electrical Impedance ◽  
Constant Phase Element ◽  
Electrochemical Impedance ◽  
High Accuracy ◽  
Metal Composite ◽  
Order Model ◽  
Unknown Parameters ◽  
Fractional Order Model ◽  
Wide Range

The accurate modeling of electrical impedance over a wide range of frequency is essential for precise dynamic modeling and control problems of Electroactive Polymer (EAP) actuators. Recently, fractional order modeling has attracted more attention due to the high accuracy. This paper deals with a fractional order electrical impedance model and its identification procedure for a class of EAP actuator named Ionic Polymer Metal Composite (IPMC). To take IPMC’s fractional characteristic into account, constant phase element (CPE) is used to construct a model structure according to Electrochemical Impedance Spectroscopy (EIS). By employing the Levy’s method in combination with genetic optimization algorithm, the unknown parameters of the resulting fractional transfer function are identified. Finally the proposed model is verified, by comparing with experimental EIS data. The results show that the fractional order model has high accuracy for representing the electrical impedance of IPMC actuator. The proposed modeling procedure is general and can also be used for any type of EAPs.

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