scholarly journals Passive Homodyne Phase Demodulation Technique Based on LF-TIT-DCM Algorithm for Interferometric Sensors

Sensors ◽  
2021 ◽  
Vol 21 (24) ◽  
pp. 8257
Author(s):  
Wanjin Zhang ◽  
Ping Lu ◽  
Zhiyuan Qu ◽  
Jiangshan Zhang ◽  
Qiang Wu ◽  
...  
Keyword(s):  
Phase Difference ◽  
Dynamic Range ◽  
Optical Power ◽  
Laser Wavelength ◽  
Identity Transformation ◽  
Dual Wavelength ◽  
Ellipse Fitting ◽  
Interferometric Sensors ◽  
Straight Line ◽  
Phase Demodulation

A passive homodyne phase demodulation technique based on a linear-fitting trigonometric-identity-transformation differential cross-multiplication (LF-TIT-DCM) algorithm is proposed. This technique relies on two interferometric signals whose interferometric phase difference is odd times of π. It is able to demodulate phase signals with a large dynamic range and wide frequency band. An anti-phase dual wavelength demodulation system is built to prove the LF-TIT-DCM algorithm. Comparing the traditional quadrature dual wavelength demodulation system with an ellipse fitting DCM (EF-DCM) algorithm, the phase difference of two interferometric signals of the anti-phase dual wavelength demodulation system is set to be π instead of π/2. This technique overcomes the drawback of EF-DCM—that it is not able to demodulate small signals since the ellipse degenerates into a straight line and the ellipse fitting algorithm is invalidated. Experimental results show that the dynamic range of the proposed anti-phase dual wavelength demodulation system is much larger than that of the traditional quadrature dual wavelength demodulation system. Moreover, the proposed anti-phase dual wavelength demodulation system is hardly influenced by optical power, and the laser wavelength should be strictly limited to lower the reference error.

A FRET based pH probe with a broad working range applicable to referenced ratiometric dual wavelength and luminescence lifetime read out

2015 ◽  
Vol 51 (28) ◽  
pp. 6145-6148 ◽  
Author(s):  
Robert J. Meier ◽  
Johann M. B. Simbürger ◽  
Tero Soukka ◽  
Michael Schäferling
Keyword(s):  
Dynamic Range ◽  
Dual Wavelength ◽  
Luminescence Lifetime ◽  
Ph Sensing ◽  
Ph Probe ◽  
Broad Dynamic Range ◽  
Europium Chelate ◽  
Ratiometric Ph Sensing

A FRET system composed of a europium chelate and carboxynaphthofluorescein enables ratiometric pH sensing with an exceptionally broad dynamic range.

scholarly journals Ultracompact on-chip photothermal power monitor based on silicon hybrid plasmonic waveguides

Nanophotonics ◽  
2017 ◽  
Vol 6 (5) ◽  
pp. 1121-1131 ◽  
Author(s):  
Hao Wu ◽  
Ke Ma ◽  
Yaocheng Shi ◽  
Lech Wosinski ◽  
Daoxin Dai
Keyword(s):  
Silicon Oxide ◽  
Dynamic Range ◽  
Optical Power ◽  
Wheatstone Bridge ◽  
Response Speed ◽  
Electrical Signal ◽  
Metal Strip ◽  
Plasmonic Waveguides ◽  
Insulator Layer ◽  
On Chip

AbstractWe propose and demonstrate an ultracompact on-chip photothermal power monitor based on a silicon hybrid plasmonic waveguide (HPWG), which consists of a metal strip, a silicon core, and a silicon oxide (SiO2) insulator layer between them. When light injected to an HPWG is absorbed by the metal strip, the temperature increases and the resistance of the metal strip changes accordingly due to the photothermal and thermal resistance effects of the metal. Therefore, the optical power variation can be monitored by measuring the resistance of the metal strip on the HPWG. To obtain the electrical signal for the resistance measurement conveniently, a Wheatstone bridge circuit is monolithically integrated with the HPWG on the same chip. As the HPWG has nanoscale light confinement, the present power monitor is as short as ~3 μm, which is the smallest photothermal power monitor reported until now. The compactness helps to improve the thermal efficiency and the response speed. For the present power monitor fabricated with simple fabrication processes, the measured responsivity is as high as about 17.7 mV/mW at a bias voltage of 2 V and the power dynamic range is as large as 35 dB.

Compact Displacement Measurement System Based on Microchip Nd:YAG Laser with Birefringence External Cavity

2008 ◽  
Vol 381-382 ◽  
pp. 39-42
Author(s):  
Y. Tan ◽  
S. Zhang
Keyword(s):  
Phase Difference ◽  
Measurement System ◽  
Nd:Yag Laser ◽  
Optical Feedback ◽  
External Cavity ◽  
Laser Wavelength ◽  
Displacement Measurement ◽  
Movement Direction ◽  
Wave Plate ◽  
Length Changes

We demonstrate a method of displacement measurement based on Nd:YAG laser with birefringence external cavity. The measurement system is composed of Nd:YAG laser, a wave plate with phase retardation of 450 and an external feedback mirror. Due to the birefringence effect, the external cavity modulates the laser output intensities in the two orthogonal directions with a phase difference of 900, which is two times to that of the wave plate. Both the in-quadrature laser intensities vary one period, when the external cavity length changes λ/2. These two channel laser intensities with phase difference of 900 can be subdivided to λ/8 after 4-fold evaluation. The movement direction of external mirror can be distinguished by the lead or lag between these two channel signals. Our method can improve the resolution of displacement measurement 4 times that of conventional optical feedback, and reach 133nm for a laser wavelength of 1.064µm.

scholarly journals G-band atmospheric radars: new frontiers in cloud physics

2014 ◽  
Vol 7 (1) ◽  
pp. 321-375 ◽  
Author(s):  
A. Battaglia ◽  
C. D. Westbrook ◽  
S. Kneifel ◽  
P. Kollias ◽  
N. Humpage ◽  
...  
Keyword(s):  
Dynamic Range ◽  
Rapid Expansion ◽  
Dual Wavelength ◽  
Doppler Velocity ◽  
Ice Clouds ◽  
Band Frequency ◽  
Boundary Layer Clouds ◽  
Radiative Processes ◽  
Microphysical Properties ◽  
Level Ice

Abstract. Clouds and associated precipitation are the largest source of uncertainty in current weather and future climate simulations. Observations of the microphysical, dynamical and radiative processes that act at cloud-scales are needed to improve our understanding of clouds. The rapid expansion of ground-based super-sites and the availability of continuous profiling and scanning multi-frequency radar observations at 35 and 94 GHz have significantly improved our ability to probe the internal structure of clouds in high temporal-spatial resolution, and to retrieve quantitative cloud and precipitation properties. However, there are still gaps in our ability to probe clouds due to large uncertainties in the retrievals. The present work discusses the potential of G-band (frequency between 110 and 300 GHz) Doppler radars in combination with lower frequencies to further improve the retrievals of microphysical properties. Our results show that, thanks to a larger dynamic range in dual-wavelength reflectivity, dual-wavelength attenuation and dual-wavelength Doppler velocity (with respect to a Rayleigh reference), the inclusion of frequencies in the G-band can significantly improve current profiling capabilities in three key areas: boundary layer clouds, cirrus and mid-level ice clouds, and precipitating snow.

scholarly journals A Fast Approximation for Adaptive Wavelength Selection for Infrared Chemical Sensors

2018 ◽  
Author(s):  
Mark Chilenski ◽  
Cara Murphy ◽  
Gil Raz
Keyword(s):  
Synthetic Data ◽  
Optical Power ◽  
Laser Wavelength ◽  
Information Theoretic ◽  
Standoff Detection ◽  
Detection And Identification ◽  
Sensor Control ◽  
Selection For ◽  
Trace Chemicals ◽  
Selection Of

<p>Active mid-infrared spectroscopy with tunable lasers is a leading technology for standoff detection and identification of trace chemicals. Information-theoretic optimal selection of the laser wavelength offers the promise of increased detection confidence at lower abundances and with fewer wavelengths. Reducing the number of wavelengths required enables faster detections and lowers sensor power consumption while keeping the optical power under eye safety limits. This paper presents an approximation to the mutual information which operates ~40000x faster than traditional techniques, thereby making near-optimal real-time sensor control computationally feasible. Application of this technique to synthetic data suggests it can reduce the number of wavelengths needed by a factor of two relative to an evenly-spaced grid, with even higher gains for chemicals with weak signatures.</p>

scholarly journals Design for tunable optofluidic optical coupler with large dynamic range

2020 ◽  
Vol 34 (25) ◽  
pp. 2050264
Author(s):  
Xionggui Tang ◽  
Fang Meng
Keyword(s):  
Simple Structure ◽  
Dynamic Range ◽  
Beam Propagation Method ◽  
Microfluidic Channel ◽  
Optical Loss ◽  
Optical Power ◽  
Optical Coupler ◽  
New Approach ◽  
Directional Coupling ◽  
Wide Potential

A novel scheme for tunable optofluidic optical coupler is proposed by combining directional coupling waveguide structures with microfluidic channel. The normalized optical power at two output ports can be dynamically manipulated by controlling the refractive index of liquid mixture in microfluidic channel. Its optical performance is numerically investigated by employing the beam propagation method (BPM). The simulated results show that the dynamic range of over 45 dB, and optical loss of below 0.06 dB can be easily achieved, and furthermore the dependence of polarization states and operation wavelength in the range from 1500 nm to 1600 nm are very low in our designed device. In addition, the tunable optofluidic coupler has advantages including simple structure and large fabrication tolerance. Accordingly, our proposed device offers a new approach for manipulating optical power output, which has wide potential application in optofluidic systems.

High Dynamic Range Microwave Photonic Link Based on Dual-Wavelength Dual-Parallel Modulation

2015 ◽  
Vol 42 (1) ◽  
pp. 0105003
Author(s):  
李向华 Li Xianghua ◽  
杨春 Yang Chun ◽  
崇毓华 Chong Yuhua ◽  
周正华 Zhou Zhenghua
Keyword(s):  
Dynamic Range ◽  
High Dynamic Range ◽  
Dual Wavelength ◽  
Microwave Photonic ◽  
High Dynamic
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