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96 results on '"Xu, Zuowei"'

5. High-Resolution and Extended-Range Fiber Bragg Grating Sensing System Based on a Microwave Photonic Filter with Period-breaking Interrogation Method

Author

Xie, Tongtong, Zhuang, Yi, Zhou, Jing, Liu, Shiwei, Wang, Haoran, Xu, Zuowei, Chen, Hao, and Fu, Hongyan

Abstract

In this paper, a high-resolution and measurement range expanded fiber Bragg grating (FBG) sensing system based on a microwave photonic filter (MPF) with period-breaking interrogation method is illustrated and experimentally demonstrated. With the dispersion of the dispersion compensating fiber (DCF) in the system, the wavelength shift of the FBG in the optical domain can be converted into the notch frequency shift of MPF in the microwave domain, thus realizing high-resolution FBG sensing. Still, the measurement range is limited due to the periodicity of MPF. An optical filter (OF) is inserted into the link that translates the wavelength shift of FBG into the relative amplitude change (RAC) of the MPF. Combined with the frequency shift and RAC of the MPF, this approach can break the periodicity of traditional interrogation methods, overcoming the limitation of measurement range while ensuring high precision. Taking strain sensing as an example, the experimental results show that the sensitivities of the FBG sensing system obtained at the frequencies of 0.9 GHz, 1.9 GHz, and 2.9 GHz are -8.19 kHz/μϵ, -26.57 kHz/μϵ, and -41.52 kHz/μϵ, respectively, and extended measurement ranges are by 1.51 times, 2.96 times, and 4.49 times, respectively. Furthermore, our proposed method, with its simple structure and unique advantages, can achieve adjustable sensitivity and an unrestricted measurement range.

Published
2024
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16. Frequency Down-Converted and Sensitivity Enhanced Fiber Optic Sensing System Based on Multi-Passband Microwave Photonic Filter by Cascaded Fiber Optic Interferometers

Author

Xie, Tongtong, Wang, Haoran, Liu, Shiwei, Dai, Weiyu, Xu, Zuowei, Chen, Hao, and Fu, Hongyan

Abstract

We propose and experimentally demonstrate a frequency down-converted and sensitivity enhanced fiber optic sensing technique based on a multi-passband microwave photonic filter (MPF) employing two cascaded fiber optic interferometers and dispersive medium. The frequency shift of the passband centered at high frequency where the sensing element is related can be down-converted to the frequency shift of low-frequency passband and enjoying narrower 3 dB bandwidth. And even greater frequency shift of passband located at low frequency have been achieved in our proposed fiber optic sensing system. Two interferometers, the Sagnac interferometer (SI), and the Mach–Zehnder interferometer (MZI) are used as a demonstration and the proof-of-concept experiments of temperature measurement are demonstrated, which show that our proposed fiber optic sensing system can down-converted the monitoring passband of SI based MPF from 687 MHz to 437 MHz, while enjoying narrower 3 dB bandwidth and maintaining the same sensitivity (0.81 MHz/°C) that of at 687 MHz, and thus bring convenience to detection. In addition, when taking the SI and MZI both as sensing elements, enhanced and adjustable sensitivity of sensing system can be achieved by adjusting the sensing fiber length of MZI. In our experiment, we have achieved enhanced and tailorable sensitivity from 0.81 MHz/°C to 8.44 MHz/°C, by monitoring the MPF's passband centered at low frequency of 437 MHz, which is about 1.59–16.55 times of the SI based single passband MPF centered at the similar frequency (446 MHz). Lower frequency and higher sensitivity can be obtained by designing the parameters of the fiber optic interferometers, which provides a powerful tool for high sensitivity, high-resolution, and low-cost fiber optic interferometer-based sensor systems.

Published
2024
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33. Transmissive fiber Bragg grating-based delay line interferometer for RZ-OOK to NRZ-OOK format conversion

Author

Liu, Xin, Xu, Zuowei, Preciad, Miguel A., Gbadebo, Adenowo, Zhang, Lin, Xiong, Jiabi, Yu, Yu, Cao, Hui, Shu, Xuewen, Liu, Xin, Xu, Zuowei, Preciad, Miguel A., Gbadebo, Adenowo, Zhang, Lin, Xiong, Jiabi, Yu, Yu, Cao, Hui, and Shu, Xuewen

Abstract

We propose a return-to-zero on-off keying (RZ-OOK) to non-return-to-zero (NRZ) OOK conversion scheme based on a transmissive phase-modulated fiber Bragg grating (PM-FBG). The PM-FBG has a spectrum similar to the combination of a delay line interferometer and a narrow band optical filter, which is designed and synthesized using numerical optimization algorithm. The coupling strength of the PM-FBG is almost uniform and the grating period varies along the fiber length according to the optimization method. The designed PM-FBG has been fabricated using advanced ultraviolet laser inscription technique. Experimental results show that such a PM-FBG can perform RZ-OOK to NRZ-OOK format conversion successfully.

Published
2019

40. Efficient postprocessing technique for fabricating surface nanoscale axial photonics microresonators with subangstrom precision by femtosecond laser

Author

Yu, Qi, Du, Yueqing, Xu, Zuowei, Wang, Peng, Zhang, Zhen, Zhu, Zece, Cao, Haoran, Sumetsky, Michael, Shu, Xuewen, Yu, Qi, Du, Yueqing, Xu, Zuowei, Wang, Peng, Zhang, Zhen, Zhu, Zece, Cao, Haoran, Sumetsky, Michael, and Shu, Xuewen

Abstract

We demonstrated the subangstrom precise correction of surface nanoscale axial photonics (SNAP) micro-resonators by the femtosecond (fs) laser postprocessing technique for the first time. The internal stress can be induced by fs laser inscriptions in the fiber, causing nanoscale effective radius variation (ERV). However, the obtained ultraprecise fabrication usually undergoes multiple tries. Here, we propose a novel postprocessing technique based on the fs laser that significantly reduces the ERV errors and improves the fabrication precision without iterative corrections. The postexposure process is achieved at the original exposure locations using lower pulse energy than that in the initial fabrication process. The results show that the ERV is nearly proportional to the pulse energy of the postexposure process. The slope of the ERV versus the pulse energy is 0.07 Å/nJ. The maximum of the postprocessed ERV can reach 8.0 Å. The repeatability was experimentally verified by accomplishing the correction on three SNAP microresonators with the precision of 0.75 Å. The developed fabrication technique with fs laser enables SNAP microresonators with new breakthrough applications for optomechanics and filters.

Published
2018

46. $8\times16$ Wavelength Selective Switch With Full Contentionless Switching.

Author

Yuan, Zhilin, Li, Wei, Yang, Rui, Yang, Liu, Wang, Fan, Guo, Jinping, Xu, Zuowei, Wang, You, Feng, Qiguang, Yang, Yuxiang, and Hu, Qianggao

Abstract

An $8\times \,\,16$ wavelength selective switch (WSS) with full contentionless switching is proposed and experimentally demonstrated. Utilizing two chips of liquid crystal on silicon, the optical wavelengths can be switched, attenuated, or blocked among 8 input ports and 16 output ports. The maximum insertion loss is less than 14 dB; the bandwidth tuning range is from 50 to 5000 GHz. The attenuation range is from 0 to 15 dB, and the optical blocking value is greater than 27 dB. Compared with the previous reports, the $8\times16$ WSS proposed in this letter is a truly contentionless WSS device with the highest number of input and output ports. [ABSTRACT FROM AUTHOR]

Published
2019
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