Optical Gas Sensors (original) (raw)
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Design of an Optical Gas Sensor Based on Silicon
The sensitivity of optical gas sensors depends on the length of interaction between detected radiation and the gas under investigation. A reduction in cell size of the sensor generally results in reduced sensitivity. Photonic crystals possess certain regions of their photonic band structure which offer low group velocities. Making use of these effects, smallervery compact -gas sensors should be possible. Problems to solve with numerical calculations are the identification of the operating point in relation to the photonic bandstructure and selection of an appropriate photonic crystal, the calculation of transmission through the photonic structure with and without the gas inside the sensor cell and the determination of an optimized anti-reflection-layer to improve the air-sensorinterface, since the low group velocity results in a high reflectivity.
Integrated Optical Gas Sensors on Silicon-on-Insulator Platform
Integrated Photonics Research, Silicon and Nanophotonics and Photonics in Switching, 2010
We demonstrate highly sensitive micro-optical hydrogen and ethanol gas sensors using SOI microring resonators (MRR) coated with sensitive films. Hydrogen concentrations below the lower explosion limit and ethanol vapor concentration below 100ppm are detected.
Optical gas sensing: a review Optical gas sensing: a review
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.
Sensors (Basel, Switzerland), 2021
We theoretically explore the potential of Si3N4 on SiO2 waveguide platform toward a wideband spectroscopic detection around the optical wavelength of 2 μm. The design of Si3N4 on SiO2 waveguide architectures consisting of a Si3N4 slot waveguide for a wideband on-chip spectroscopic sensing around 2 μm, and a Si3N4 multi-mode interferometer (MMI)-based coupler for light coupling from classical strip waveguide into the identified Si3N4 slot waveguides over a wide spectral range are investigated. We found that a Si3N4 on SiO2 slot waveguide structure can be designed for using as optical interaction part over a spectral range of interest, and the MMI structure can be used to enable broadband optical coupling from a strip to the slot waveguide for wideband multi-gas on-chip spectroscopic sensing. Reasons for the operating spectral range of the system are discussed.
Gas Sensor Based on Silicon Nitride Integrated Long Period Grating
2022 IEEE Sensors
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Silicon photonic dual-gas sensor for H_2 and CO_2 detection
Optics Express, 2017
We report a silicon photonic dual-gas sensor based on a wavelength-multiplexed microring resonator array for simultaneous detection of H 2 and CO 2 gases. The sensor uses Pd as the sensing layer for H 2 gas and a novel functional material based on the Polyhexamethylene Biguanide (PHMB) polymer for CO 2 gas sensing. Gas sensing experiments showed that the PHMB-functionalized microring exhibited high sensitivity to CO 2 gas and excellent selectivity against H 2. However, the Pd-functionalized microring was found to exhibit sensitivity to both H 2 and CO 2 gases, rendering it ineffective for detecting H 2 in a gas mixture containing CO 2. We show that the dual-gas sensing scheme can allow for accurate measurement of H 2 concentration in the presence of CO 2 by accounting for the cross-sensitivity of Pd to the latter.
Porous Silicon Structures as Optical Gas Sensors
Sensors, 2015
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.
Proceedings of SPIE, 2004
The bandstructure of photonic crystals offers intriguing possibilities for the manipulation of electromagnetic waves. During the last years, research has mainly focussed on the application of these photonic crystal properties in the telecom area. We suggest utilization of photonic crystals for sensor applications such as qualitative and quantitative gas and liquid analysis. Taking advantage of the low group velocity and certain mode distributions for some k-points in the bandstructure of a photonic crystal should enable the realization of very compact sensor devices. We show different device configurations of a photonic crystal based on macroporous silicon that fulfill the demands to serve as a compact gas sensor.
Compact Gas Sensor Using Silicon-on-Insulator Loop-Terminated Mach–Zehnder Interferometer
Photonics
In this paper, we propose a compact optical gas sensor based on the widespread silicon-on-insulator (SOI) technology, operating in the near-infrared (NIR) region around the 1.55 µm wavelength. The sensor employs a loop-terminated Mach–Zehnder interferometer (LT-MZI) with a slot waveguide and a strip waveguide for the sensing arm and the reference arm, respectively. For the same arm length, the LT-MZI can achieve a detection limit two times lower than that of the conventional MZI. Different sensor components were designed, and the optimum dimensions were obtained using finite-difference eigenmode (FDE) and finite-difference time-domain (FDTD) solvers. With a sensing arm length of only 150 μm, our sensor achieves a device sensitivity of 1070 nm/RIU and a figure-of-merit (FOM) as high as 280.8 RIU−1 at the 1.55 μm wavelength. Higher values of FOM can be attained by employing a longer sensing arm. The whole sensor is subjected to air cladding; thus, there is no need for oxide deposition...
A Comprehensive Review of Semiconductor-Type Gas Sensors for Environmental Monitoring
Review of Computer Engineering Research
In this paper a review of different semiconductor-type gas sensors is presented. The different types of gas sensors from various companies like Hanwei, Libelium, Sandbox Electronics and Sensor Tech SGX are discussed along with their technical specifications. Environment is surrounded by various sorts of gases cum pollutants and it is utmost necessary to keep a efficient check on them as these gases can cause trouble to the health of human beings and pollute environment drastically. The main objective of this research paper is to present all sorts of gas sensors which are based on semiconductors and to generate awareness regarding which sensor is best for which detection. However, for more improved sensitivity and selectivity for these sensors, future trends and outlook for researchers is also suggested. The paper can also act as base for researchers to get hold of these sensors to develop a market ready product like drone or robot for Environmental Gas Detection.