Author
Hoi Lut Ho
Bio: Hoi Lut Ho is an academic researcher from Hong Kong Polytechnic University. The author has contributed to research in topics: Optical fiber & Photonic-crystal fiber. The author has an hindex of 26, co-authored 102 publications receiving 2667 citations.
Papers published on a yearly basis
Papers
More filters
TL;DR: The modeling results of an all-fiber gas detector that uses photonic crystal fiber (PCF) and the relative sensitivity of the PCF as a function of the fiber parameters is calculated.
Abstract: We report the modeling results of an all-fiber gas detector that uses photonic crystal fiber (PCF). The relative sensitivity of the PCF as a function of the fiber parameters is calculated. Gas-diffusion dynamics that affect the sensor response time is investigated theoretically and experimentally. A practical PCF sensor aiming for high sensitivity gas detection is proposed.
306 citations
TL;DR: A miniature fiber-tip pressure sensor was built by using an extremely thin graphene film as the diaphragm, which acts as a light reflector and forms a low finesse Fabry-Perot interferometer.
Abstract: A miniature fiber-tip pressure sensor was built by using an extremely thin graphene film as the diaphragm. The graphene also acts as a light reflector, which, in conjunction with the reflection at the fiber end-air interface, forms a low finesse Fabry-Perot interferometer. The graphene based sensor demonstrated pressure sensitivity over 39.4 nm/kPa with a diaphragm diameter of 25 μm. The use of graphene as diaphragm material would allow highly sensitive and compact fiber-tip sensors.
252 citations
TL;DR: With this method, the central hollow-core and the holes in the cladding region can be selectively infiltrated, which allows for the fabrication of novel hybrid polymer- silica and liquid-silica MOFs for various applications.
Abstract: A simple method for fabricating selective injection microstructured optical fibers (MOFs) using a conventional fusion splicer is described. The effects of fusion current, fusion duration and offset position on the hole collapse property of the MOFs are investigated. With this method, the central hollow-core and the holes in the cladding region can be selectively infiltrated, which allows for the fabrication of novel hybrid polymer-silica and liquid-silica MOFs for various applications.
234 citations
TL;DR: In this paper, a fiber-optic Fabry-Perot acoustic sensor with a ~100-nmthick multilayer graphene diaphragm is reported, which demonstrates a pressureinduced deflection of 1100 nm/kPa and a noise equivalent acoustic signal level of ~ 60 μPa/Hz1/2 at the frequency of 10 kHz.
Abstract: A fiber-optic Fabry-Perot acoustic sensor with a ~100-nm-thick multilayer graphene diaphragm is reported. Acoustic testing demonstrates a pressure-induced deflection of 1100 nm/kPa and a noise equivalent acoustic signal level of ~ 60 μPa/Hz1/2 at the frequency of 10 kHz. The sensor exhibits a flat frequency response from 0.2 to 22 kHz and may be useful for highly sensitive acoustic sensing.
206 citations
TL;DR: The realization of photothermal interferometry with low-cost near infrared semiconductor lasers and fibre-based technology allows a class of optical sensors with compact size, ultra sensitivity and selectivity, applicability to harsh environment, and capability for remote and multiplexed multi-point detection and distributed sensing.
Abstract: Photothermal interferometry is an ultra-sensitive spectroscopic means for trace chemical detection in gas- and liquid-phase materials. Previous photothermal interferometry systems used free-space optics and have limitations in efficiency of light–matter interaction, size and optical alignment, and integration into photonic circuits. Here we exploit photothermal-induced phase change in a gas-filled hollow-core photonic bandgap fibre, and demonstrate an all-fibre acetylene gas sensor with a noise equivalent concentration of 2 p.p.b. (2.3 × 10−9 cm−1 in absorption coefficient) and an unprecedented dynamic range of nearly six orders of magnitude. The realization of photothermal interferometry with low-cost near infrared semiconductor lasers and fibre-based technology allows a class of optical sensors with compact size, ultra sensitivity and selectivity, applicability to harsh environment, and capability for remote and multiplexed multi-point detection and distributed sensing. Photothermal interferometry systems using free-space optics have limits in terms of light–matter interaction efficiency, size, optical alignment and integration. Here, Jin et al. use a gas-filled hollow-core photonic bandgap fibre to demonstrate an all-fibre gas sensor with ultrahigh sensitivity and dynamic range.
198 citations
Cited by
More filters
31 Oct 2001
TL;DR: The American Society for Testing and Materials (ASTM) as mentioned in this paper is an independent organization devoted to the development of standards for testing and materials, and is a member of IEEE 802.11.
Abstract: The American Society for Testing and Materials (ASTM) is an independent organization devoted to the development of standards.
3,792 citations
Journal Article•
[...]
TL;DR: Development of this more comprehensive model of the behavior of light draws upon the use of tools traditionally available to the electrical engineer, such as linear system theory and the theory of stochastic processes.
Abstract: Course Description This is an advanced course in which we explore the field of Statistical Optics. Topics covered include such subjects as the statistical properties of natural (thermal) and laser light, spatial and temporal coherence, effects of partial coherence on optical imaging instruments, effects on imaging due to randomly inhomogeneous media, and a statistical treatment of the detection of light. Development of this more comprehensive model of the behavior of light draws upon the use of tools traditionally available to the electrical engineer, such as linear system theory and the theory of stochastic processes.
1,364 citations
TL;DR: In this article, the authors present the basis for each technique, recent developments in methods and performance limitations, and present a performance comparison of different techniques, taking data reported over the preceding decade, and draw conclusions from this benchmarking.
Abstract: The detection and measurement of gas concentrations using the characteristic optical absorption of the gas species is important for both understanding and monitoring a variety of phenomena from industrial processes to environmental change. This study reviews the field, covering several individual gas detection techniques including non-dispersive infrared, spectrophotometry, tunable diode laser spectroscopy and photoacoustic spectroscopy. We present the basis for each technique, recent developments in methods and performance limitations. The technology available to support this field, in terms of key components such as light sources and gas cells, has advanced rapidly in recent years and we discuss these new developments. Finally, we present a performance comparison of different techniques, taking data reported over the preceding decade, and draw conclusions from this benchmarking.
1,293 citations
TL;DR: A review of recent developments in the rapidly changing and advancing field of smart fabric sensor and electronic textile technologies can be found in this article, which summarizes the basic principles and approaches employed when building fabric sensors as well as the most commonly used materials and techniques used in electronic textiles.
Abstract: This paper provides a review of recent developments in the rapidly changing and advancing field of smart fabric sensor and electronic textile technologies. It summarizes the basic principles and approaches employed when building fabric sensors as well as the most commonly used materials and techniques used in electronic textiles. This paper shows that sensing functionality can be created by intrinsic and extrinsic modifications to textile substrates depending on the level of integration into the fabric platform. The current work demonstrates that fabric sensors can be tailored to measure force, pressure, chemicals, humidity and temperature variations. Materials, connectors, fabric circuits, interconnects, encapsulation and fabrication methods associated with fabric technologies prove to be customizable and versatile but less robust than their conventional electronics counterparts. The findings of this survey suggest that a complete smart fabric system is possible through the integration of the different types of textile based functional elements. This work intends to be a starting point for standardization of smart fabric sensing techniques and e-textile fabrication methods.
618 citations