{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,6]],"date-time":"2026-05-06T18:49:47Z","timestamp":1778093387355,"version":"3.51.4"},"reference-count":23,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2016,5,12]],"date-time":"2016-05-12T00:00:00Z","timestamp":1463011200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"the International Science and Technology Cooperation Program of China","award":["2014DFA11170"],"award-info":[{"award-number":["2014DFA11170"]}]},{"DOI":"10.13039\/501100001809","name":"the National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["61475128"],"award-info":[{"award-number":["61475128"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"name":"the Key Grant Project of Chinese Ministry of Education","award":["313049"],"award-info":[{"award-number":["313049"]}]},{"name":"the Fundamental Research Fund for the Central Universities","award":["2682014RC22"],"award-info":[{"award-number":["2682014RC22"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Phase-sensitive optical time domain reflectometry (\u0424-OTDR) attracts much attention due to its capability of telling the type and position of an intrusion simultaneously. In recent decades, coherent \u0424-OTDR has been demonstrated to realize long-distance detection. For coherent \u0424-OTDR, there are three typical demodulation schemes in the reported studies. However, they still cannot realize real-time monitoring to satisfy practical demands. A simple and effective demodulation method based on self-mixing has been put forward to demodulate the beat signal in coherent \u0424-OTDR. It not only saves a local electrical oscillator and frequency locked loop, but also demodulates the beat signal without residual frequency. Several vibrations with different frequency were separately applied at the same location of a 42.5 km fiber. The spatial resolution of 10 m and frequency response range from 8 Hz to 980 Hz have been achieved. The precise location with signal-to-noise ratio of 21.4 dB and broadband measurement demonstrate the self-mixing scheme can demodulate the coherent \u0424-OTDR signal effectively.<\/jats:p>","DOI":"10.3390\/s16050681","type":"journal-article","created":{"date-parts":[[2016,5,12]],"date-time":"2016-05-12T10:18:45Z","timestamp":1463048325000},"page":"681","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":43,"title":["Self-Mixing Demodulation for Coherent Phase-Sensitive OTDR System"],"prefix":"10.3390","volume":"16","author":[{"given":"Haijun","family":"He","sequence":"first","affiliation":[{"name":"Center for Information Photonics &amp; Communications, School of Information Science and Technology, Southwest Jiaotong University, Chengdu 610031, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1272-1959","authenticated-orcid":false,"given":"Li-Yang","family":"Shao","sequence":"additional","affiliation":[{"name":"Center for Information Photonics &amp; Communications, School of Information Science and Technology, Southwest Jiaotong University, Chengdu 610031, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zonglei","family":"Li","sequence":"additional","affiliation":[{"name":"Center for Information Photonics &amp; Communications, School of Information Science and Technology, Southwest Jiaotong University, Chengdu 610031, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zhiyong","family":"Zhang","sequence":"additional","affiliation":[{"name":"Center for Information Photonics &amp; Communications, School of Information Science and Technology, Southwest Jiaotong University, Chengdu 610031, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xihua","family":"Zou","sequence":"additional","affiliation":[{"name":"Center for Information Photonics &amp; Communications, School of Information Science and Technology, Southwest Jiaotong University, Chengdu 610031, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Bin","family":"Luo","sequence":"additional","affiliation":[{"name":"Center for Information Photonics &amp; Communications, School of Information Science and Technology, Southwest Jiaotong University, Chengdu 610031, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Wei","family":"Pan","sequence":"additional","affiliation":[{"name":"Center for Information Photonics &amp; Communications, School of Information Science and Technology, Southwest Jiaotong University, Chengdu 610031, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lianshan","family":"Yan","sequence":"additional","affiliation":[{"name":"Center for Information Photonics &amp; Communications, School of Information Science and Technology, Southwest Jiaotong University, Chengdu 610031, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2016,5,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2375","DOI":"10.1364\/AO.16.002375","article-title":"Optical time domain reflectometer","volume":"16","author":"Barnoski","year":"1997","journal-title":"Appl. Opt."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"24","DOI":"10.1109\/50.17729","article-title":"Real-time long range complementary correlation optical time domain reflectometer","volume":"7","author":"Nazarathy","year":"1989","journal-title":"J. Lightwave Technol."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Zhao, Q., Xia, L., Wan, C., Hu, J., Jia, T., Gu, M., Zhang, L., Kang, L., Chen, J., Zhang, X., and Wu, P. (2015). Long-haul and high-resolution optical time domain reflectometry using superconducting nanowire single-photon detectors. Sci. Rep., 5.","DOI":"10.1038\/srep10441"},{"key":"ref_4","unstructured":"Taylor, H.F., and Lee, C.E. (1993). Apparatus and Method for Fiber Optic Intrusion Sensing. (5,194 847), U.S. Patent."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1968","DOI":"10.1364\/AO.46.001968","article-title":"Field test of a distributed fiber-optic intrusion sensor system for long perimeters","volume":"46","author":"Juarez","year":"2007","journal-title":"Appl. Opt."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Wu, H., Wang, Z.N., Peng, F., Peng, Z.P., Li, X.Y., Wu, Y., and Rao, Y.J. (2014, January 2\u20136). Field test of a fully distributed fiber optic intrusion detection system for long-distance security monitoring of national borderline. Proceedings of the 23rd International Conference on Optical Fiber Sensors, Santander, Spain.","DOI":"10.1117\/12.2058504"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"2081","DOI":"10.1109\/JLT.2005.849924","article-title":"Distributed fiber-optic intrusion sensor system","volume":"23","author":"Juarez","year":"2005","journal-title":"J. Lightwave Technol."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"3631","DOI":"10.1109\/JLT.2013.2286223","article-title":"Coherent noise reduction in high visibility phase-sensitive optical time domain reflectometer for distributed sensing of ultrasonic waves","volume":"31","author":"Martins","year":"2013","journal-title":"J. Lightwave Technol."},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Rao, Y.J., Luo, J., Ran, Z.L., Yue, J.F., Luo, X.D., and Zhou, Z. (2009, January 5\u201314). Long-distance fiber-optic \u03a6-OTDR intrusion sensing system. Proceedings of the 20th International Conference on Optical Fibre Sensors, Edinburgh, UK.","DOI":"10.1117\/12.835324"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"345","DOI":"10.1007\/s13320-015-0279-3","article-title":"Phase-sensitive optical time-domain reflectometry amplified by gated Raman pump","volume":"5","author":"Li","year":"2015","journal-title":"Photonic Sens."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"5866","DOI":"10.1364\/OL.39.005866","article-title":"Ultra-long phase-sensitive OTDR with hybrid distributed amplification","volume":"39","author":"Wang","year":"2014","journal-title":"Opt. Lett."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"13804","DOI":"10.1364\/OE.22.013804","article-title":"Ultra-long high sensitivity \u03a6-OTDR for high spatial resolution intrusion detection of pipelines","volume":"22","author":"Peng","year":"2014","journal-title":"Opt. Express"},{"key":"ref_13","first-page":"3243","article-title":"Distributed vibration sensor based on coherent detection of phase-OTDR","volume":"28","author":"Lu","year":"2010","journal-title":"J. Lightwave Technol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1091","DOI":"10.1109\/LPT.2011.2157337","article-title":"High sensitivity distributed vibration sensor based on polarization maintaining configurations of phase-OTDR","volume":"23","author":"Qin","year":"2011","journal-title":"IEEE Photonic Technol. Lett."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"8601","DOI":"10.3390\/s120708601","article-title":"Recent progress in distributed fiber optic sensors","volume":"12","author":"Bao","year":"2012","journal-title":"Sensors"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"20459","DOI":"10.1364\/OE.20.020459","article-title":"Continuous wavelet transform for non-stationary vibration detection with phase-OTDR","volume":"20","author":"Qin","year":"2012","journal-title":"Opt. Express"},{"key":"ref_17","unstructured":"Qin, Z. (2013). Distributed Optical Fiber Vibration Sensor Based on Rayleigh Backscattering. [Ph.D. Thesis, University of Ottawa]."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1955","DOI":"10.1109\/LPT.2013.2276124","article-title":"All fiber distributed vibration sensing using modulated time-difference pulses","volume":"25","author":"He","year":"2013","journal-title":"IEEE Photonic Technol. Lett."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Pan, Z., Liang, K., Ye, Q., Cai, H., Qu, R., and Fang, Z. (2011, January 13\u201316). Phase-sensitive OTDR system based on digital coherent detection. Proceedings of the Asia Communications and Photonics Conference and Exhibition, Shanghai, China.","DOI":"10.1364\/ACP.2011.83110S"},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Pan, Z., Liang, K., Zhou, J., Ye, Q., Cai, H., and Qu, R. (2012, January 15\u201319). Interference-fading-free phase-demodulated OTDR system. Proceedings of the 22nd International Conference on Optical Fiber Sensor, Beijing, China.","DOI":"10.1117\/12.975656"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"5600","DOI":"10.1364\/AO.37.005600","article-title":"Interferometric optical time-domain reflectometry for distributed optical-fiber sensing","volume":"37","author":"Shatalin","year":"1998","journal-title":"Appl. Opt."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"2628","DOI":"10.1109\/JLT.2015.2396359","article-title":"Distributed vibration sensing over 125 km with enhanced SNR using phi-OTDR over an URFL cavity","volume":"33","author":"Martins","year":"2015","journal-title":"J. Lightwave Technol."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1349","DOI":"10.1109\/LPT.2015.2421354","article-title":"The Development of an-OTDR System for Quantitative Vibration Measurement","volume":"27","author":"Tu","year":"2015","journal-title":"IEEE Photonic Technol. 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