Temperature-compensated multi-point refractive index sensing based on a cascaded Fabry-Perot cavity and FMCW interferometry

Abstract

We proposed a novel temperature-compensated multi-point refractive index (RI) sensing system by the combination of the cascaded Fabry-Perot (FP) sensors and the frequency modulated continuous wave (FMCW) interferometry. The former is used for simultaneous sensing of RI and temperature, and the latter is used for multiplexing a series of the cascaded FP sensors to realize multi-point sensing. By means of Fourier transform-based algorithms, the interference spectra of each sub-FP sensors can be divided and demodulated independently. Experimentally, three cascaded FP sensors are multiplexed to verify multi-point RI and temperature sensing ability. RI sensitivity up to ∼1200 nm/RIU is obtained within RI range from 1.3330 to 1.3410, and temperature sensitivity up to ∼0.17 nm/°C is obtained within temperature range from 20 °C to 80 °C. The RI precision is as high as 10−5 RIU and the temperature precision is as high as 0.05 °C. In addition, the prospective multiplexing number could reach about 4000 estimated by the minimum detectable light power. The proposed sensing system has potential advantages in the practical applications that require a large number sensing points.

Surface plasmon resonance biosensor with laser heterodyne feedback for highly-sensitive and rapid detection of COVID-19 spike antigen

“…The sensitivity is calculated to be 1.07 × 10 6 mV/RIU and the noise-limited resolution is calculated to be 3.75 × 10 −8 RIU, which is better than most reported results. ( Giorgini et al, 2013 ; Li et al, 2020 ; Mataji-Kojouri et al, 2020 ; Park and Park, 2021 ; Wu et al, 2021 ; Zhu et al, 2021 ), showing that this biosensor is capable of detecting the viral antigen.…”

Temperature-Compensated Multi-Point Strain Sensing Based on Cascaded FBG and Optical FMCW Interferometry

“…The light signal output from the reference arm can be expressed by [ 20 , 27 ] where is the initial amplitude of the output light signal, is the initial frequency, is the linear tuning speed of the light source, is the initial phase, which represents the phase of the random fluctuations of the light source at time .…”

“…After bandpass filtering and moving average processing, noise signal is reduced. Then, using the inverse fast Fourier transform (IFFT) algorithm [ 20 , 29 ], the peaks of interest are extracted and converted into time domain (spatial domain) so that the wavelength of each grating is demodulated out. The equal relation between time domain and wavelength domain can be obtained according to the formula where is the sampling interval of the DAQ, is the wavelength scanning range of TLS, and N is the sampling number.…”

“…Optical FMCW interference technology, also known as optical frequency domain reflectometry (OFDR) technology, is a technique that detects backward Rayleigh scattering to obtain position information on an optical fiber link. OFDR is widely used in distributed sensing [ 17 , 18 , 19 , 20 , 21 ]. In recent years, a number of researchers have used a combination of FBG and OFDR techniques for strain measurements.…”

Investigation of Fabry Perot Interferometer Temperature Sensor Based on Hollow Core Anti-Resonance Optical Fiber

“…processing and health, agricultural biological manufacturing and electronic manufacturing, etc. Demonstrating advantages of strong anti-interference, compact structure, easy layout and online monitoring [4], [5], optical fiber temperature sensors have been widely used in various industries and environments, for instance, petroleum exploration, marine monitoring, biomedical [1] and aerospace engineering [2], [3], etc. With the development of optical fiber sensing technology, more recently, a variety of novel temperature sensors have been developed based on Bragg fiber [6], [7], stress-optical effect (SOE) [8], Michelson interferometer (MI) [9], Mach-Zehnder interferometer (MZI) [10], hollow fiber interferometer (HI) [11], [12] and Fabry-Perot interferometer (FPI) [13], [14].…”