The cornerstone of fiber-optic distributed vibration/acoustic sensing: Ф-OTDR

Fiber-optic distributed vibration/acoustic sensing(DVS/DAS) technology achieves breakthrough performance and explores broad cornerstone industrial applications.

Ultra-high extinction ratio optical pulse generation with a thin film lithium niobate modulator for distributed acoustic sensing

We experimentally demonstrate ultra-high extinction ratio(ER)optical pulse modulation with an electro-optical modulator(EOM)on thin film lithium niobate(TFLN)and its application for fiber optic distributed acoustic sensing(DAS).An interface carrier effect leading to a relaxation-tail response of TFLN EOM is discovered,which can be well addressed by a small compensation component following the main driving signal.An ultrahigh ER>50 dB is achieved by canceling out the tailed response during pulse modulation using the EOM based on a cascaded Mach–Zehnder interferometer(MZI)structure.The modulated optical_(√)pulses are then utilized as a probe light for a DAS system,showing a sensitivity up to-62.9 dB·rad∕Hz~2(7 pε/Hz)for 2-km single-mode sensing fiber.Spatial crosstalk suppression of 24.9 dB along the fiber is also obtained when the ER is improved from 20 dB to 50 dB,clearly revealing its importance to the sensing performance.

Spectrally programmable Raman fiber laser with adaptive wavefront shaping

Raman fiber lasers(RFLs)have broadband tunability due to cascaded stimulated Raman scattering,providing extensive degrees of freedom for spectral manipulation.However,the spectral diversity of RFLs depends mainly on the wavelength flexibility of the pump,which limits the application of RFLs.Here,a spectrally programmable RFL is developed based on two-dimensional spatial-to-spectral mapping of light in multimode fibers(MMFs).Using an intracavity wavefront shaping method combined with genetic algorithm optimization,we launch light with a selected wavelength(s)at MMF output into the active part of the laser for amplification.In contrast,the light of undesired wavelengths is blocked.We demonstrate spectral shaping of the high-order RFL,including a continuously tunable single wavelength and multiple wavelengths with a designed spectral shape.Due to the simultaneous control of different wavelength regions,each order of Raman Stokes light allows flexible and independent spectral manipulation.Our research exploits light manipulation in a fiber platform with multieigenmodes and nonlinear gain,mapping spatial control to the spectral domain and extending linear light control in MMFs to active light emission,which is of great significance for applications of RFLs in optical imaging,sensing,and spectroscopy.

Recent Advances in Phase-Sensitive Optical Time Domain Reflectometry (Ф-OTDR)

Phase-sensitive optical time domain reflectometry(Ф-OTDR)is an effective way to detect vibrations and acoustic waves with high sensitivity,by interrogating coherent Rayleigh backscattering light in sensing fiber.In particular,fiber-optic distributed acoustic sensing(DAS)based on theФ-OTDR with phase demodulation has been extensively studied and widely used in intrusion detection,borehole seismic acquisition,structure health monitoring,etc.,in recent years,with superior advantages such as long sensing range,fast response speed,wide sensing bandwidth,low operation cost and long service lifetime.Significant advances in research and development(R&D)ofФ-OTDR have been made since 2014.In this review,we present a historical review ofФ-OTDR and then summarize the recent progress ofФ-OTDR in the Fiber Optics Research Center(FORC)at University of Electronic Science and Technology of China(UESTC),which is the first group to carry out R&D ofФ-OTDR and invent ultra-sensitive DAS(uDAS)seismometer in China which is elected as one of the ten most significant technology advances of PetroChina in 2019.It can be seen that theФ-OTDR/DAS technology is currently under its rapid development stage and would reach its climax in the next 5 years.

Biochemical sensing in graphene-enhanced microfiber resonators with individual molecule sensitivity and selectivity

Photonic sensors that are able to detect and track biochemical molecules offer powerful tools for information acquisition in applications ranging from environmental analysis to medical diagnosis.The ultimate aim of biochemical sensing is to achieve both quantitative sensitivity and selectivity.As atomically thick films with remarkable optoelectronic tunability,graphene and its derived materials have shown unique potential as a chemically tunable platform for sensing,thus enabling significant performance enhancement,versatile functionalization and flexible device integration.Here,we demonstrate a partially reduced graphene oxide(prGO)inner-coated and fiber-calibrated Fabry-Perot dye resonator for biochemical detection.Versatile functionalization in the prGO film enables the intracavity fluorescent resonance energy transfer(FRET)to be chemically selective in the visible band.Moreover,by measuring the intermode interference via noise canceled beat notes and locked-in heterodyne detection with Hz-level precision,we achieved individual molecule sensitivity for dopamine,nicotine and single-strand DNA detection.This work combines atomic-layer nanoscience and high-resolution optoelectronics,providing a way toward high-performance biochemical sensors and systems.

Electrically controllable laser frequency combs in graphene-fibre microresonators

Laser frequency combs emitting ultrafast pulses of light,at equidistantly discrete frequencies,are cornerstones of modern information networks.In recent years,the generation of soliton combs in microcavities with ultrahighquality factors has established microcombs as out-oflaboratory tools.However,the material and geometry of a laser cavity,which determine comb formation,are difficult to electrically tune.Such dynamic control can further enrich the diversity of comb outputs and help to actively stabilize them.

Optical rogue wave in random fiber laser

The famous demonstration of optical rogue waves(RWs),a powerful tool to reveal the fundamental physics in different laser scenarios,opened a flourishing time for temporal statistics.Random fiber laser(RFL)has likewise attracted wide attention due to its great potential in multidisciplinary demonstrations and promising applications.However,owing to the distinctive cavity-free structure,it is a scientific challenge to achieve temporal localized RWs in RFLs,whose feedback arises from multiple scattering in disordered medium.Here,we report the exploration of RW in the highly skewed,transient intensity of an incoherently pumped RFL for the first time,to our knowledge,and unfold the involved kinetics successfully.The corresponding frequency domain measurements demonstrate that the RW event arises from a crucial sustained stimulated Brillouin scattering process with intrinsic stochastic nature.This investigation highlights a novel path to fully understanding the complex physics,such as photon propagation and localization,in disordered media.

OFS Research Over the Last 10 Years at CQU ＆ UESTC

这篇文章考察我察觉到的新光纤维(OFS ) 在重庆大学和中国的电子科技的大学在中国研究活动最后十年，自从我在 1999 从英国回来了。在长时期纤维栅栏(LPFG ) 的研究进步，分布式的纤维察觉到系统和 microfiber 传感器被介绍。为 LPFG，有 LPFG 的高周波的 CO2 激光脉搏类型的处理方法制作了，为光察觉到和光通讯的相关应用被描述。为察觉到系统的分布式的纤维，光纤的极化光时间领域反射计(POTDR ) ，光纤的阶段敏感的光时间领域反射计(-OTDR) 和 Brillouin 光时间域分析器(BOTDA ) 分别地被开发。为 microfiber 传感器，我们主要为折射索引和加速察觉到集中于结共鸣器和它的应用程序，等等。

Kilometers Long Graphene-Coated Optical Fibers for Fast Thermal Sensing

The combination of optical fiber with graphene has greatly expanded the application regimes of fiber optics,from dynamic optical control and ultrafast pulse generation to high precision sensing.However,limited by fabrication,previous graphene-fiber samples are typically limited in the micrometer to centimeter scale,which cannot take the inherent advantage of optical fibers—longdistance optical transmission.Here,we demonstrate kilometers long graphene-coated optical fiber(GCF)based on industrial graphene nanosheets and coating technique.The GCF shows unusually high thermal diffusivity of 24.99 mm^(2) s^(-1) in the axial direction,measured by a thermal imager directly.This enables rapid thermooptical response both in optical fiber Bragg grating sensors at one point(18-fold faster than conventional fiber)and in long-distance distributed fiber sensing systems based on backward Rayleigh scattering in optical fiber(15-fold faster than conventional fiber).This work realizes the industrial-level graphene-fiber production and provides a novel platform for two-dimensional material-based optical fiber sensing applications.

Study on Fiber-Optic Low-Coherence Interferometric and Fiber Bragg Grating Sensors

这篇文章在最后二十年在光纤的传感器上考察作者研究工作。它包括二个方面：低连贯的 interferometric 传感器(步兵登陆艇) 和纤维布拉格栅栏(FBG ) 传感器。为步兵登陆艇传感器，作者工作主要在坎特伯雷( UKC )在肯特的大学为 Fizeau 和 Fabry-Perot interferometric 传感器集中于讯问和 multiplexing 方法，英国，并且在重庆大学( CQU )和电子科学的大学与中国( UESTC )的技术在新奇 Fabry-Perot interferometric 传感器和他们的 multiplexing 方法上学习，中国分别地。为 FBG 传感器，很多个 multiplexing 计划被建议并且与另外的光纤维基于 FBG 传感器和它的联合为多参数测量和长途的测量的实现在 UKC，然后新奇方法证明传感器也在 CQU 与 UESTC 被报导。因此，作者们在这二个话题上学习能被划分成二个时期，在 UKC 并且在 CQU 与 UESTC，中国。这评论在如此的一个时间序列被介绍。

Fiber-Optic Microstructure Sensors:A Review

This paper reviews a wide variety of fiber-optic microstructure(FOM)sensors,such as fiber Bragg grating(FBG)sensors,long-period fiber grating(LPFG)sensors,Fabry-Perot interferometer(FPI)sensors,Mach-Zchnder interferometer(MZI)sensors,Michelson interferometer(MI)sensors,and Sagnac interferometer(SI)sensors.Each FOM sensor has been introduced in the terms of structure types,fabrication methods,and their sensing applications.In addition,the sensing characteristics of different structures under the same type of FOM sensor are compared,and the sensing characteristics of the all FOM sensors,including advantages,disadvantages,and main sensing parameters,are summarized.We also discuss the future development of FOM sensors.

Recent Progress in Fiber Optofluidic Lasing and Sensing

Fiber optofluidic laser(FOFL)integrates optical fiber microcavity and microfluidic channel and provides many unique advantages for sensing applications.FOFLs not only inherit the advantages of lasers such as high sensitivity,high signal-to-noise ratio,and narrow linewidth,but also hold the unique features of optical fiber,including ease of integration,high repeatability,and low cost.With the development of new fiber structures and fabrication technologies,FOFLs become an important branch of optical fiber sensors,especially for application in biochemical detection.In this paper,the recent progress on FOFL is reviewed.We focuse mainly on the optical fiber resonators,gain medium,and the emerging sen sing applicatio ns.The prospects for FOFL are also discussed.We believe that the FOFL sensor provides a promising technology for biomedical analysis and environmental monitoring.

Optical Sensing Based on Light Coupling Between Two Parallel Long-Period Fiber Gratings

为折射索引和极小的排水量的测量的新光基于紧张的察觉到机制在这篇论文被建议，它基于修改在二个平行长时期的纤维栅栏之间联合的光的数量。有实验和模拟结果的这察觉到的机制的特征被表明。

Dental Imaging With Near-Infrared Transillumination Using Random Fiber Laser

Contrary to the conventional detection method like radiography,the near infrared light source has been demonstrated to be suitable for dental imaging due to different reflectivity among enamel,dentin,and caries lesion.In this paper,three light sources with different bandwidths based on a transillumination method are compared.The contrast among enamel,dentin,and caries lesion is calculated in different situations.The experimental results show that the random fiber laser has the best comprehensive quality in dental imaging due to its high spectral density,low coherence,and deep penetration.This work provides a guidance for light source selection in dental imaging.

Nanoparticle mediated microcavity random laser

This paper reports a coherent random microcavity laser that consists of a disordered cladding(scattering) layer and a light-amplification core filled with dye solution. Cold cavity analysis indicates that the random resonance modes supported by the proposed cavity can be effectively excited. With introducing the gain material, random lasing by specific modes is observed to show typical features of coherent random lasers, such as spatially incoherent emission of random modes. By inserting a metal nanoparticle into the gain region, emission wavelength/intensity of the random lasers can be considerably tuned by changing the position of the inserted nanoparticle,opening up new avenues for controlling output of random lasers and sensing applications(e.g., small particleidentification, location, etc.).

Simultaneous Force and Temperature Measurement Using Optical Microfiber Asymmetrical Interferometer

新奇光 microfiber 不对称的 Fabry-Perot interferometric (MAFPI ) 传感器为力量和温度的同时的测量被开发。MAFPI 结构被弱纤维布拉格形成栅栏(FBG ) ， microfiber 的节，和劈开的纤维结束出现。从低反射率的 FBG 反映的 narrowband 横梁和从夫累Ｘ尔思考的宽带横梁介入导致它的唯一的察觉到表演。察觉到的力量被检测导致的穗对比改变的拐弯损失执行，当布拉格波长移动为温度测量被采用时。9.8 pm/ 戠 ?猯'T 的敏感？？

Graphene-Fiber Biochemical Sensors: Principles, Implementations, and Advances

Single atomically thick graphene, with unique structural flexibility, surface sensitivity, and effective light-mater interaction, has shown exceptional advances in optoelectronics. It opens a door for diverse functionalized photonic devices, ranging from passive polarizers to active lasers and parametric oscillators. Among them, graphene-fiber biochemical sensors combine the merits of both graphene and fiber structures, demonstrating impressively high performances, such as single-molecule detectability and fast responsibility. These graphene-fiber biochemical sensors can offer tools in various applications, such as gas tracing, chemical analysis, and medical testing. In this paper, we review the emerging graphene-fiber biochemical sensors comprehensively, including the sensing principles, device fabrications, systematic implementations, and advanced applications. Finally, we summarize the state-of-the-art graphene-fiber biochemical sensors and put forward our outlooks on the development in the future.