Optical Fiber and Gelatin Based Fabry-Perot Interferometric Humidity Sensor
ZHONG Yusong, DONG Xinyong, XU Pengbai, and YANG Jun
A Fabry-Perot Interferometer (FPI) was constructed by fusion splicing a Hollow Core Fiber (HCF) with a length of tens of microns at the end of a single-mode fiber and coating gelatin film at the free end of the HCF. Relative humidity measurement was achieved by detecting wavelength shift of the interference spectrum with humidity level changes. Experimental results show that high sensitivity of 192 pm/%RH has been obtained in the temperature range of 20 ℃ within the range of 20%~80%RH and the measurement accuracy and repeatability are quite good. In addition, the sensitivity of 173 pm/%RH and 194 pm/%RH were obtained by humidity increasing experiments at 15 ℃ and 25 ℃, respectively. In order to measure temperature has also been achieved by cascading a fiber Bragg grating sensor with the FPI sensor head. The optical fiber humidity sensor possesses several advantages including simple fabrication, high sensitivity, and temperature measurement. It has good potential in the field of humidity measurement.
  • Jan. 25, 2022
  • Acta Photonica Sinica
  • Vol.50 Issue, 12 1206003 (2021)
  • DOI:10.3788/gzxb20215012.1206003
Characteristics of Flexible Fibre Bragg Grating Pulse Wave Sensor
GE Ziyang, WANG Yan, ZHAO Hui, JIN Ping, and FAN Baocun
To address the shortcomings of piezoelectric and optoelectronic pulse wave sensors that are susceptible to interference in strong electromagnetic interference environments, a flexible material encapsulated Fibre Optic Grating (FBG) pulse wave sensor is proposed for measuring human radial artery pulse signals. The optimal package thickness and the position of the optical fibre in the substrate were first investigated using comsol finite element simulation software. Based on the simulation results, the sensor thickness of 5 mm and the optical fibre encapsulation at 1 mm from the lower surface of the substrate were optimised to combine the strain transfer effect and the flexibility of the sensor. The FBG flexible pulse wave sensor was fabricated and the human flexural artery pulses were collected from ten test subjects. The denoised signals were well preserved by a modified threshold wavelet method, and the signal-to-noise ratios were above 40, and the peak, tidal and repulse waveform recognition rates were 100%, 100% and 90% respectively. The results show that the flexible substrate FBG pulse wave sensor can effectively acquire and identify pulse wave signals, providing a theoretical basis and application support for further applications.
  • Jan. 25, 2022
  • Acta Photonica Sinica
  • Vol.50 Issue, 12 1206002 (2021)
  • DOI:10.3788/gzxb20215012.1206002
Experimental Study on Deuterium Gas Treatment for Reducing the Hydrogen Diffusion of G.657 Optical Fiber
FU Minglei, HE Bao, CHEN Kun, WU Yiwen, ZHANG Wenqi, LIU Jianzhong, ZHUANG Mingjie, and LU Chunxiao
Hydrogen diffusion is an important factor that causes additional absorption loss in optical fibers. The concave G.657 fiber with the inner cladding was chosen as the experimental fiber, and the structure and attenuation factors of the G.657 fiber were analyzed. The mechanism of deuterium gas to eliminate the hydrogen sensitivity of the fiber was explained, and the fiber hydrogen diffusion experiment was designed to carry out the deuterium gas treatment formula. By adjusting the two key parameters of deuterium concentration and processing time, the additional attenuation value of the fiber under different experimental conditions was obtained. The comparison experiment results and the tracking retest results show that 0.9% deuterium gas concentration and 80 h deuterium treatment time are suitable for reducing the hydrogen diffusion of G.657 optical fiber.
  • Jan. 25, 2022
  • Acta Photonica Sinica
  • Vol.50 Issue, 12 1206001 (2021)
  • DOI:10.3788/gzxb20215012.1206001
Distributed Fiber-Optic Acoustic Seismic Geophone for Petroleum Geology Exploration
Ni Jiasheng, Liu Tiegen, Shang Ying, and Zhao Yanjie
  • Jan. 24, 2022
  • Laser & Optoelectronics Progress
  • Vol.59 Issue, 3 0306006 (2022)
  • DOI:10.3788/LOP202259.0306006
Propagation and Attenuation Characterization of Hollow-Core Anti-Resonant Fiber at 2.60-4.35 μm
Zhu Kuan, Zhang Xin, Lu Wenju, Wang Feifei, Zhang Baitao, He Jingliang, Wang Yingying, and Wang Pu
To study the transmission ability of hollow-core anti-resonance fiber, a mid-infrared laser transmission experiment was carried out using a self-made nodeless hollow-core anti-resonance fiber from 2.6 μm to 4.35 μm spectral region. The fiber cladding consists of seven silica capillary tubes, the average wall thickness is 800 nm, the outer diameter of the fiber is 365 μm, and the core diameter is 115 μm. A tunable mid-infrared source was used as a broadband light source. The laser propagation capability of the fiber at 2.60 μm, 3.27 μm, 3.41 μm, 3.80 μm, 4.08 μm, 4.21 μm, and 4.35 μm was tested. And the transmission loss at this spectral region of the fiber was measured. Results show that the fiber can realize low-loss light guide from 2.6 μm to 4.08 μm band, with the lowest transmission loss of 0.037 dB/m at 3.27 μm. The transmission loss of the fiber is 3.200 dB/m at 4.08 μm and 0.788 dB/m at 4.35 μm, where the attenuation of bulk silica is 1000 dB/m and 3000 dB/m, respectively. Hollow-core anti-resonance fiber has great potential in the application of mid-infrared laser flexible delivery.
  • Jan. 24, 2022
  • Laser & Optoelectronics Progress
  • Vol.59 Issue, 3 0306004 (2022)
  • DOI:10.3788/LOP202259.0306004
Research on Properties of Highly Nonlinear Bi2O3-GeO2-Ga2O3 Photonic Crystal Fiber
Tan Fang, Xu Pengfei, Zhou Dechun, Yang Qiang, Wang Lili, and Song Xiangyang
Highly nonlinear photonic crystal fiber has the characteristics of small core and large refractive index contrast. In this work, the photonic crystal fiber (PCF) with a special structure based on Bi2O3-GeO2-Ga2O3 core glass material was designed. Using full-vector finite element method while the perfect matched layer boundary condition, the birefringence coefficients of the PCF at the wavelengths of 1.55 μm and 1.80 μm are 2.89×10-2 and 3.28×10-2, respectively. The dispersion curve shows, when the ellipticity of the inner cladding elliptical air hole is 0.6, the photonic crystal fiber with structural parameters M=d/Λ of 0.5 and 0.6 has two zero dispersion points, indicating it has negative dispersion characteristics. The limiting losses of X polarization and Y polarization at 1.55 μm are 3.8784×10-5?4.5739×10-5 dB·km-1 and 3.5203×10-5?4.2147×10-5 dB?km-1, respectively. This work provides reference for nonlinear optical fiber fields such as optical communication and microstructure optical fiber sensor.
  • Jan. 24, 2022
  • Laser & Optoelectronics Progress
  • Vol.59 Issue, 3 0306003 (2022)
  • DOI:10.3788/LOP202259.0306003
Design and Evaluation of High-Sensitivity Underwater Optical Communication Transceiver Based on Digital Signal Processing
Ren Tingrui, Yu Xiaonan, Tong Shoufeng, Tian Mingguang, Wang Tong, Zhang Peng, Wang Dashuai, and An Ning
ConclusionsThis study describes the underwater OOK channel model and analyses the correspondence between BER and SNR of underwater OOK modulation methods in different water quality conditions. To cope with the impact of an underwater channel on the optical signal transmission, an underwater optical communication transmitter-transceiver based on hardware circuits and field-programmable logic gate devices is designed. The digital signal processing modules such as FIR filtering (to improve the SNR of the system), adaptive judgement threshold and sliding mean filtering are designed to improve the communication BER performance. The communication performance of the underwater communication transmitter and transceiver is verified under different water quality conditions. The experimental results show that the terminal can achieve a sensitivity of -38 dm at a transmission rate of 5 Mbps and BER of 10-6. The transmission distance can reach 20, 10 and 4.5 m in class I, class II and class III waters, respectively. In the class III water test, the communication distance of 5 m and BER of 10-5 can meet the demand of voice transmission. The distortion-free image and SD video transmission function can be realised at the communication distance of 4.5 m and BER of 10-6, verifying the feasibility of underwater optical communication based on digital signal processing.
  • Jan. 24, 2022
  • Chinese Journal of Lasers
  • Vol.49 Issue, 4 0406005 (2022)
  • DOI:10.3788/CJL202249.0406005
High-Precision Optical Fibre Network Health Online Monitoring System Based on Incoherent Optical Frequency Domain Reflection Technology
Yu Miao, Ji Shunbing, Liu Hai, Yang Guang, Huang Shengjun, Liu Jun, He Yutong, and Sun Mingyang
ConclusionsBased on the mechanism of the IOFDR technique, this study proposed a low-cost, high-precision and distributed fibre quality detection method by taking Rayleigh backscattering light in the fibre as the signal light combined with its light wave conduction equation. Additionally, its numerical model is derived in detail. The system structure is designed. A high-precision online health monitoring system for optical fibre networks is developed, which realises the quality and health monitoring of optical fibre networks by frequent-spatial transformation. The experimental verification shows that the system can realise distributed detection of 10 km optical fibre with very low optical power (
  • Jan. 24, 2022
  • Chinese Journal of Lasers
  • Vol.49 Issue, 4 0406003 (2022)
  • DOI:10.3788/CJL202249.0406003
Dual-Core Terahertz Fiber Directional Coupler
Huang Xu, Luo Xingfang, Zuo Xiangyu, Wang Shaohua, and Zhu Yuanfeng
In this paper, a two-core terahertz fiber directional coupler is proposed. Two dielectric cylinders are suspended in the interior of two annular dielectric layers to form two fiber cores. By adjusting the structural parameters, the coupling length of the two polarization modes can be equal, thus realizing polarization independence of the coupling length. The length of the coupler can be one half of the coupling length of the fiber mode, and the transmission loss can be reduced with the short length of the device. The coupler is numerically analyzed by finite element method. The results show that the length of the coupler is 0.535 cm, and the transmission loss of x and y polarization modes is 0.23 dB and 0.19 dB, respectively. Under the premise that the coupling length difference between the two polarization modes is less than 1%, the bandwidth reaches 220 GHz.
  • Jan. 19, 2022
  • Acta Optica Sinica
  • Vol.42 Issue, 2 0206006 (2022)
  • DOI:10.3788/AOS202242.0206006
Analysis and Experimental Study on Transmission Characteristics of Double Sagnac Loop Filter
Cui Wenxiang, Zhou Xuefang, Hu Miao, Bi Meihua, Yang Guowei, Li Qiliang, and Wang Tianshu
ConclusionsIn this study, the transmission characteristics of a double Sagnac loop filter, composed of two segments of PMF in parallel, are analyzed, simulated and measured in detail, which proves that the proposed double Sagnac loop filter has the polarization-independent characteristic and the tunable channel spacing. According to the results of simulation and measurement, a channel spacing tunable multi-wavelength erbium-doped fiber laser utilizing a double Sagnac loop filter with the assistance of the FWM effect is designed. The laser can output multi-wavelength lasing lines with channel spacings of 0.35 nm and 0.9 nm. Owing to the polarization-independent characteristic of the double Sagnac loop filter, the polarization-dependent devices are not interfere with the transmission spectra of the filter. Thus, the double Sagnac loop filter exhibits the simple structure, polarization-independence, the tunability of channel spacing, and a great potential application in the field of multi-wavelength fiber lasers.
  • Jan. 18, 2022
  • Chinese Journal of Lasers
  • Vol.49 Issue, 4 0406006 (2022)
  • DOI:10.3788/CJL202249.0406006