{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,14]],"date-time":"2026-06-14T03:34:04Z","timestamp":1781408044796,"version":"3.54.1"},"reference-count":32,"publisher":"MDPI AG","issue":"22","license":[{"start":{"date-parts":[[2022,11,21]],"date-time":"2022-11-21T00:00:00Z","timestamp":1668988800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100012166","name":"National Key R&amp;D Program of China","doi-asserted-by":"publisher","award":["2019YFF0301802"],"award-info":[{"award-number":["2019YFF0301802"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100012166","name":"National Key R&amp;D Program of China","doi-asserted-by":"publisher","award":["201903D121124"],"award-info":[{"award-number":["201903D121124"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100012166","name":"National Key R&amp;D Program of China","doi-asserted-by":"publisher","award":["YDZJSX2022B005"],"award-info":[{"award-number":["YDZJSX2022B005"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Key Research and Development (R&amp;D) Projects of Shanxi Province","award":["2019YFF0301802"],"award-info":[{"award-number":["2019YFF0301802"]}]},{"name":"Key Research and Development (R&amp;D) Projects of Shanxi Province","award":["201903D121124"],"award-info":[{"award-number":["201903D121124"]}]},{"name":"Key Research and Development (R&amp;D) Projects of Shanxi Province","award":["YDZJSX2022B005"],"award-info":[{"award-number":["YDZJSX2022B005"]}]},{"name":"Central Guidance on Local Science and Technology Development Fund of Shanxi Province","award":["2019YFF0301802"],"award-info":[{"award-number":["2019YFF0301802"]}]},{"name":"Central Guidance on Local Science and Technology Development Fund of Shanxi Province","award":["201903D121124"],"award-info":[{"award-number":["201903D121124"]}]},{"name":"Central Guidance on Local Science and Technology Development Fund of Shanxi Province","award":["YDZJSX2022B005"],"award-info":[{"award-number":["YDZJSX2022B005"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>We have demonstrated the use of a flat multi-wavelength Brillouin erbium-doped fiber laser (MWBEFL) based on a Sagnac loop with an unpumped erbium-doped fiber (Un-EDF) as a high-sensitivity sensor. A Sagnac loop with a Un-EDF was used as power equalizer to achieve multi-wavelength power flatness by adjusting the birefringence beat length properly. In the experiments, the best result obtained in terms of Brillouin Stokes lines and output power flatness was \u00b10.315 dB and the optical signal-to-noise ratio (OSNR) was 18.97 dB within a 33 nm bandwidth range from 1532.0 nm to 1565.0 nm. The flatness of the 33 nm bandwidth range varied from \u00b10.315 dB to \u00b11.38 dB and the average OSNR was about 17.51 dB. The peak power values of Brillouin Stokes lines observed under different wavelengths were extremely close and their range of fluctuation was about \u00b10.37 dB. These experimental results were close to our previous experimental values obtained using a passive Sagnac loop with a Un-EDF. The flat range covering almost the entire C-band has broad application prospects in high-sensitivity distributed optical fiber sensing and wavelength-division multiplexing.<\/jats:p>","DOI":"10.3390\/s22229017","type":"journal-article","created":{"date-parts":[[2022,11,22]],"date-time":"2022-11-22T05:18:57Z","timestamp":1669094337000},"page":"9017","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Flat Multi-Wavelength Brillouin Erbium-Doped Fiber Laser Based on a Sagnac Loop for High-Sensitivity Sensor"],"prefix":"10.3390","volume":"22","author":[{"given":"Liang","family":"Chen","sequence":"first","affiliation":[{"name":"State Key Laboratory of Dynamic Testing Technology, School of Instrument and Electronics, North University of China, Taiyuan 030051, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jian","family":"He","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Dynamic Testing Technology, School of Instrument and Electronics, North University of China, Taiyuan 030051, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yi","family":"Liu","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Dynamic Testing Technology, School of Instrument and Electronics, North University of China, Taiyuan 030051, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,11,21]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"10233","DOI":"10.1364\/OE.14.010233","article-title":"160-line multiwavelength generation of linear-cavity self-seeded Brillouin-Erbium fiber laser","volume":"14","author":"Zhan","year":"2006","journal-title":"Opt. Express"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"025104","DOI":"10.1088\/1612-202X\/aaf69f","article-title":"A single-longitudinal-mode narrow-linewidth dual-wavelength fiber laser using a microfiber knot resonator","volume":"16","author":"Yang","year":"2019","journal-title":"Laser Phys. Lett."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"3173","DOI":"10.1109\/JLT.2019.2912432","article-title":"Switchable 0.612-nm-spaced Dual-wavelength fiber laser with Sub-kHz linewidth, Ultra-High OSNR, Ultra-Low RIN, and Orthogonal Polarization Outputs","volume":"37","author":"Feng","year":"2019","journal-title":"J. Light. Technol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"065104","DOI":"10.1088\/1555-6611\/aab655","article-title":"Switchable dual-wavelength single-longitudinal-mode erbium fiber laser utilizing a dual-ring scheme with a saturable absorber","volume":"28","author":"Yang","year":"2018","journal-title":"Laser Phys."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"452","DOI":"10.1016\/j.optcom.2007.09.046","article-title":"Multiwavelength self-seeded Brillouin-erbium fiber laser with 45-nm tunable range","volume":"281","author":"Huang","year":"2008","journal-title":"Opt. Commun."},{"key":"ref_6","first-page":"486","article-title":"Self-seeded multiwavelength Brillouin\u2013erbium fiber laser","volume":"30","author":"Song","year":"2005","journal-title":"Opt. Express"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"9731","DOI":"10.1364\/OE.15.009731","article-title":"Tunable self-seeded multiwavelength Brillouin-Erbium fiber laser with enhanced power efficiency","volume":"15","author":"Zhang","year":"2005","journal-title":"Opt. Express"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"16","DOI":"10.1016\/j.optlastec.2019.01.025","article-title":"Single-mode erbium fiber dual-ring laser with 60-nm workable wavelength tenability","volume":"114","author":"Yang","year":"2019","journal-title":"Opt. Laser Technol."},{"key":"ref_9","first-page":"1113","article-title":"Large-region tunable optical bistability in saturable absorber-based single-frequency Brillouin fiber lasers","volume":"32","author":"Zhang","year":"2015","journal-title":"Opt. Phy."},{"key":"ref_10","first-page":"1635","article-title":"Tunable bistability in hybrid Brillouin\u2013erbium single-frequency fiber laser with saturable absorber","volume":"33","author":"Wang","year":"2016","journal-title":"Opt. Phy."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1198","DOI":"10.1109\/50.596966","article-title":"Brillouin\/erbium fiber lasers","volume":"15","author":"Cowle","year":"1997","journal-title":"J. Light. Technol."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"3339","DOI":"10.1364\/AO.55.003339","article-title":"Stable multi-wavelength fiber laser with single-mode fiber in a Sagnac loop","volume":"55","author":"Wang","year":"2016","journal-title":"Appl. Opt."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"942","DOI":"10.1109\/LPT.2004.833097","article-title":"Tunable multiwavelength Brillouin-erbium fiber laser with a polarization-maintaining fiber Sagnac loop filter","volume":"16","author":"Song","year":"2004","journal-title":"IEEE Photon. Technol. Lett."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"107","DOI":"10.1016\/j.optcom.2017.07.080","article-title":"Comb multi-wavelength, rectangular pulse, passively mode-locked fiber laser enhanced by un-pumped erbium-doped fiber","volume":"406","author":"Guo","year":"2018","journal-title":"Opt. Commun."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"528","DOI":"10.1016\/j.ijleo.2018.09.063","article-title":"Selectable and stable C-band multi-wavelength ring cavity erbium-doped fiber laser employing Sagnac loop and tunable filter","volume":"176","author":"He","year":"2019","journal-title":"Optik"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.yofte.2018.02.006","article-title":"Tunable erbium-doped fiber laser based on optical fiber Sagnac interference loop with angle shift spliced polarization maintaining fibers","volume":"42","author":"Ding","year":"2018","journal-title":"Opt. Fiber Technol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"180","DOI":"10.1016\/j.optlastec.2016.01.032","article-title":"Stable and tunable self-seeded multiwavelength Brillouin-erbium fiber laser with higher OSNR","volume":"81","author":"Zou","year":"2016","journal-title":"Opt. Laser Technol."},{"key":"ref_18","first-page":"0901704","article-title":"Self-seeded multiwavelength dual-cavity Brillouinerbium fiber laser","volume":"20","author":"Rahman","year":"2014","journal-title":"IEEE J. Sel. Top. Quantum Electron."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"14682","DOI":"10.1364\/OE.19.014682","article-title":"Tunable multiwavelength generation based on Brillouin-erbium comb fiber laser assisted by multiple four-wave mixing processes","volume":"19","author":"Tang","year":"2011","journal-title":"Opt. Express"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1501010","DOI":"10.1109\/JPHOT.2013.2271713","article-title":"150-channel four wave mixing based multiwavelength Brillouin-erbium doped fiber laser","volume":"5","author":"Yaacob","year":"2013","journal-title":"IEEE Photonics J."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"386","DOI":"10.1109\/68.556082","article-title":"EDFA Transient Response to Channel Loss in WDM Transmission System","volume":"9","author":"Srivastava","year":"1997","journal-title":"IEEE Photonics Techno. Lett."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"7649","DOI":"10.1364\/OE.16.007649","article-title":"Tunable range enhancement of Brillouin-erbium fiber laser utilizing Brillouin pump pre-amplification technique","volume":"16","author":"Mahdi","year":"2008","journal-title":"Opt. Express"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1046","DOI":"10.1016\/j.ijleo.2010.07.003","article-title":"Simple tunable multiwavelength Brillouin\/Erbium fiber laser utilizing short-length photonic crystal fiber","volume":"122","author":"Zhao","year":"2011","journal-title":"Optik"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"17200","DOI":"10.1364\/OE.17.017200","article-title":"Tunable multiwavelength SOA fiber laser with ultra-narrow wavelength spacing based on nonlinear polarization rotation","volume":"17","author":"Zhang","year":"2009","journal-title":"Opt. Express"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"327","DOI":"10.1016\/j.yofte.2017.04.004","article-title":"Tunable multiwavelength Brillouin-Raman fiber laser in a linear cavity with spectrum reshaped by Rayleigh scattering","volume":"36","author":"Wang","year":"2017","journal-title":"Opt. Fiber Technol."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"125105","DOI":"10.1088\/1555-6611\/aae278","article-title":"A tunable multi-wavelength Brillouin-erbium linear cavity fiber laser with higher optical signal to noise ratio","volume":"12","author":"Ma","year":"2018","journal-title":"Laser Phys."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"3471","DOI":"10.1364\/OPEX.13.003471","article-title":"Widely tunable linear cavity multiwavelength Brillouin-erbium fiber lasers","volume":"13","author":"Adikan","year":"2005","journal-title":"Opt. Express"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"3000","DOI":"10.1364\/OE.15.003000","article-title":"Flat amplitude multiwavelength Brillouin-Raman comb fiber laser in Rayleigh-scattering-enhanced linear cavity","volume":"15","author":"Zamzuri","year":"2007","journal-title":"Opt. Express"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"19382","DOI":"10.1364\/OE.25.019382","article-title":"Wide bandwidth and flat multiwavelength Brillouin-erbium fiber laser","volume":"25","author":"Chonlan","year":"2017","journal-title":"Opt. Express"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"3124","DOI":"10.1364\/OE.26.003124","article-title":"Flat amplitude and wide multiwavelength Brillouin\/erbium fiber laser based on Fresnel reflection in a micro-air cavity design","volume":"26","author":"Sarmani","year":"2018","journal-title":"Opt. Express"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"4496","DOI":"10.1109\/JLT.2021.3071422","article-title":"An EDFA-gain equalizer based on a Sagnac loop with an unpumped erbium-doped fiber","volume":"39","author":"Liu","year":"2021","journal-title":"J. Light. Technol."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"32591","DOI":"10.1364\/OE.25.032591","article-title":"High sensitivity distributed temperature fiber sensor using stimulated Brillouin scattering","volume":"25","author":"Iezzi","year":"2017","journal-title":"Opt. Express"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/22\/22\/9017\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T01:22:57Z","timestamp":1760145777000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/22\/22\/9017"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,11,21]]},"references-count":32,"journal-issue":{"issue":"22","published-online":{"date-parts":[[2022,11]]}},"alternative-id":["s22229017"],"URL":"https:\/\/doi.org\/10.3390\/s22229017","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,11,21]]}}}