Optical fiber technology has changed the world by enabling extraordinary growth in world-wide communications and sensing.The rapid development and wide deployment of optical fiber sensors are driven by their excellent...Optical fiber technology has changed the world by enabling extraordinary growth in world-wide communications and sensing.The rapid development and wide deployment of optical fiber sensors are driven by their excellent sensing performance with outstanding flexibility,functionality,and versatility.Notably,the research on specialty optical fibers is playing a critical role in enabling and proliferating the optical fiber sensing applications.This paper overviews recent developments in specialty optical fibers and their sensing applications.The specialty optical fibers are reviewed based on their innovations in special structures,special materials,and technologies to realize lab in/on a fiber.An overview of sensing applications in various fields is presented.The prospects and emerging research areas of specialty optical fibers are also discussed.展开更多
New types of communication cables were found to be needed already during the 1960-decade,because the copper cables had,and still would have,too high attenuation and especially limited bandwidth,due to extremely high d...New types of communication cables were found to be needed already during the 1960-decade,because the copper cables had,and still would have,too high attenuation and especially limited bandwidth,due to extremely high dispersion at communication signals above 2 Mbit/s.Already the first commercially available multimode optical fibers(1979),developed from pure silica glass with a Ge-doped core,had much lower attenuation at signal frequencies of the order of 2-9 Mbit/s and above it.However,fiber core,cladding and coating materials,cable structures and materials,as well as manufacturing-,measurements-and test methods have been needed to be developed much further to get the reliable fiber cable communication networks.The important development stages and solutions to the most significant childhood problems of the optical fibers and cables are described in this paper.Now over 500 million km of optical fibers are manufactured and installed worldwide for the communication networks.The understanding of how to make the fibers with the very good transmission,mechanical and reliability properties exists at the manufacturers of the fibers and cables.展开更多
In-situ measurement of internal solitary waves(ISWs)is complicated in the ocean due to their randomness.At present,the ISWs are mainly detected by the chain structure of conductivity-temperature-depth systems(CTDs)or ...In-situ measurement of internal solitary waves(ISWs)is complicated in the ocean due to their randomness.At present,the ISWs are mainly detected by the chain structure of conductivity-temperature-depth systems(CTDs)or temperature sensors.The high cost limits the spatial resolution,which ultimately affects the measuring accuracy of the ISW amplitude.In this paper,we developed an experimental measurement system for detecting ISWs based on the stimulated Raman scattering in distributed optical fibers.This system has the advantages of high precision,low cost,and easy operation.The experimental results show that the system is consistent with CTDs in the measurement of vertical ocean temperature variation.The spatial resolution of the system can reach 1.0 m and the measuring accuracy of temperature is 0.2℃.We successfully detected 3 ISWs by the system in the South China Sea and two optical remote sensing images collected on May 18,2021,the same day of two detected ISWs,verify the occurrence of the measured ISWs.We used the image pairs method to calculate the phase velocity of ISW and the result is 1.71 ms^(-1).By extracting the distances between wave packets,it can be found that the semi-diurnal tide generates the detected ISWs.The impact of the tidal current velocity on the ISW in amplitude is undeniable.Undoubtedly,the system has a great application prospect for detecting ISWs and other dynamic phenomena in the ocean.展开更多
Modulation instabilities in the randomly birefringent two-mode optical fibers (RB-TMFs) are analyzed in detail by accounting the effects of the differential mode group delay (DMGD) and group velocity dispersion (...Modulation instabilities in the randomly birefringent two-mode optical fibers (RB-TMFs) are analyzed in detail by accounting the effects of the differential mode group delay (DMGD) and group velocity dispersion (GVD) ratio between the two modes, both of which are absent in the randomly birefringent single-mode optical fibers (RB-SMFs). New MI characteristics are found in both normal and anomalous dispersion regimes. For the normal dispersion, without DMGD, no MI exists. With DMGD, a completely new MI band is generated as long as the total power is smaller than a critical total power value, named by Per, which increases significantly with the increment of DMGD, and reduces dramatically as GVD ratio and power ratio between the two modes increases. For the anomalous dispersion, there is one MI band without DMGD. In the presence of DMGD, the MI gain is reduced generally. On the other hand, there also exists a critical total power (Per), which increases (decreases) distinctly with the increment of DMGD (GVD ratio of the two modes) but varies complicatedly with the power ratio between the two modes. Two MI bands are present for total power smaller than Per, and the dominant band can be switched between the low and high frequency bands by adjusting the power ratio between the two modes. The M1 analysis in this paper is verified by numerical simulation.展开更多
We investigate the microscopic optical force density distributions respectively inside a subwavelength-diameter(SD)fiber with flat endface and inside one with oblique endface by using a finite-difference time-domain...We investigate the microscopic optical force density distributions respectively inside a subwavelength-diameter(SD)fiber with flat endface and inside one with oblique endface by using a finite-difference time-domain(FDTD) method.Optical force density distributions at the fiber endfaces can now be readily available. The complete knowledge of optical force density distributions not only reveal features regarding the microscopic near-field optomechanical interaction, but also provide straightforward explanations for the sideway deflections and other mechanical motions. Our results can provide a useful reference for better understanding the mechanical influence when light transports in a microscale or nanoscale structure and for developing future highly-sensitive optomechanical devices.展开更多
In order to analyze the effect of wavelength-dependent radiation-induced attenuation (RIA) on the mean trans- mission wavelength in optical fiber and the scale factor of interferometric fiber optic gyroscopes (IFOG...In order to analyze the effect of wavelength-dependent radiation-induced attenuation (RIA) on the mean trans- mission wavelength in optical fiber and the scale factor of interferometric fiber optic gyroscopes (IFOGs), three types of polarization-maintaining (PM) fibers are tested by using a 60Co γ-radiation source. The observed different mean wave- length shift (MWS) behaviors for different fibers are interpreted by color-center theory involving dose rate-dependent absorption bands in ultraviolet and visible ranges and total dose-dependent near-infrared absorption bands. To evaluate the mean wavelength variation in a fiber coil and the induced scale factor change for space-borne IFOGs under low radiation doses in a space environment, the influence of dose rate on the mean wavelength is investigated by testing four germanium (Ge) doped fibers and two germanium-phosphorus (Ge-P) codoped fibers irradiated at different dose rates. Experimental results indicate that the Ge-doped fibers show the least mean wavelength shift during irradiation and their mean wavelength of optical signal transmission in fibers will shift to a shorter wavelength in a low-dose-rate radiation environment. Finally, the change in the scale factor of IFOG resulting from the mean wavelength shift is estimated and tested, and it is found that the significant radiation-induced scale factor variation must be considered during the design of space-borne IFOGs.展开更多
The effects of color centers' absorption on fibers and interferometric fiber optical gyroscopes(IFOGs) are studied in the paper. The irradiation induced attenuation(RIA) spectra of three types of polarization-mai...The effects of color centers' absorption on fibers and interferometric fiber optical gyroscopes(IFOGs) are studied in the paper. The irradiation induced attenuation(RIA) spectra of three types of polarization-maintaining fibers(PMFs), i.e.,P-doped, Ge-doped, and pure silica, irradiated at 100 Gy and 1000 Gy are measured in a wavelength range from 1100 nm to1600 nm and decomposed according to the Gaussian model. The relationship of the color centers absorption intensity with radiation dose is investigated based on a power model. Furthermore, the effects of all color centers' absorption on RIA and mean wavelength shifts(MWS) at 1300 nm and 1550 nm are discussed respectively. Finally, the random walk coefficient(RWC) degradation induced from RIA and the scale factor error induced by MWS of the IFOG are simulated and tested at a wavelength of 1300 nm. This research will contribute to the applications of the fibers in radiation environments.展开更多
Stress-induced birefringence and modal birefringence of single-mode specialty optical fibers with three stress regions are numerically analyzed by the vector finite element method. Stress distribution and stress-induc...Stress-induced birefringence and modal birefringence of single-mode specialty optical fibers with three stress regions are numerically analyzed by the vector finite element method. Stress distribution and stress-induced birefringence distribution of three kinds of optical fibers with different cross structures are presented and compared, and the influence on the stress- induced birefringence by temperature change are analyzed as well. The results show that the fibers with three-stress regions have a lower linear birefringence, which is very important for the fabrication of the circular polaxization-maintalning fiber with high performance drawn from the same fiber preform by using the spinning method.展开更多
Many experimental investigations on the temperature dependence of the refractive index of optical fibers have been reported previously, however a satisfying theoretical explanation for it is still absent. In this pape...Many experimental investigations on the temperature dependence of the refractive index of optical fibers have been reported previously, however a satisfying theoretical explanation for it is still absent. In this paper, a theoretical model about the temperature dependence of the refractive index of optical fibers is presented and it is in agreement with the previous experimental results. This work is a significant reference for the research and development of temperature sensors based on optical fiber delay lines.展开更多
A simple fiber sensor to measure angular displacement with high resolution, which is based on whispering gallery mode (WGM) resonance in bent optical fibers,is proposed. The sensor is composed of a single loop forme...A simple fiber sensor to measure angular displacement with high resolution, which is based on whispering gallery mode (WGM) resonance in bent optical fibers,is proposed. The sensor is composed of a single loop formed by loosely tying a knot using single mode fiber. To measure the transmission spectra, a tunable laser and an optic power meter are connected to the two ends of fi- ber loop, respectively. Significant WGM resonances occur over the investigated wavelength range for all the sensors with different bend radius. The angular-displacement sensitivity is studied in the range from -0. 1°to 0. 1°. The detection limit of 1.49 × 10 ^-7 rad can be achieved for the detecting system with the resolution of lpm. The simple loop-structure fiber sensor has potential application prospect in the field of architecture or bridge building with low detection limit and low cost.展开更多
We propose an alternative approach to compensation of intermodal interactions in few-mode optical fibers by means of digital backpropagation.Instead of solving the inverse generalized multimode nonlinear Schr?dinger e...We propose an alternative approach to compensation of intermodal interactions in few-mode optical fibers by means of digital backpropagation.Instead of solving the inverse generalized multimode nonlinear Schr?dinger equation,we accomplish backpropagation of the multimode signals with help of their near-field intensity distributions captured by a camera.We demonstrate that this task can successfully be handled by a deep neural network and provide a proof of concept by training an autoencoder for backpropagation of six linearly polarized[LP]modes of a step-index fiber.展开更多
The surface-enhanced Raman scattering(SERS) optical fiber probes were successfully prepared by self-assembling on polyelectrolyte multilayers. Gold nanorods(Au NRs) were used as SERS enhancement material to give excel...The surface-enhanced Raman scattering(SERS) optical fiber probes were successfully prepared by self-assembling on polyelectrolyte multilayers. Gold nanorods(Au NRs) were used as SERS enhancement material to give excellent biological affinity and stability to the SERS optical fiber probes. Au NRs were synthesized by seed growth method. The synergistic effect between AgNO_(3) and surfactant was investigated, and the highest yield was found when AgNO_(3) was 500 uL. Meanwhile, different SERS optical fiber probes were obtained by selecting silane coupling agent, polyelectrolyte multilayer and graphene oxide(GO) to treat quartz fiber. It was found that the SERS optical fiber probes obtained by the self-assembled on polyelectrolyte multilayers method performed better than those by other methods. In addition, Mapping was combined with finite element simulation to analyze the electromagnetic field distribution at the fiber end face.The electromagnetic field distribution of Au NRs was investigated, the difference of electromagnetic field intensity around the Au NRs with different arrangements was compared, the strongest signal was obtained when the Au NRs were head-to-head. Finally, sensitivity of the optimized SERS optical fiber probes could reach 10^(-9)mol/L, with excellent stability and repeatability.展开更多
The battery technology progress has been a contradictory process in which performance improvement and hidden risks coexist.Now the battery is still a“black box”,thus requiring a deep understanding of its internal st...The battery technology progress has been a contradictory process in which performance improvement and hidden risks coexist.Now the battery is still a“black box”,thus requiring a deep understanding of its internal state.The battery should“sense its internal physical/chemical conditions”,which puts strict requirements on embedded sensing parts.This paper summarizes the application of advanced optical fiber sensors in lithium-ion batteries and energy storage technologies that may be mass deployed,focuses on the insights of advanced optical fiber sensors into the processes of one-dimensional nano-micro-level battery material structural phase transition,electrolyte degradation,electrode-electrolyte interface dynamics to three-dimensional macro-safety evolution.The paper contributes to understanding how to use optical fiber sensors to achieve“real”and“embedded”monitoring.Through the inherent advantages of the advanced optical fiber sensor,it helps clarify the battery internal state and reaction mechanism,aiding in the establishment of more detailed models.These advancements can promote the development of smart batteries,with significant importance lying in essentially promoting the improvement of system consistency.Furthermore,with the help of smart batteries in the future,the importance of consistency can be weakened or even eliminated.The application of advanced optical fiber sensors helps comprehensively improve the battery quality,reliability,and life.展开更多
Optical endoscopy has become an essential diagnostic and therapeutic approach in modern biomedicine for directly observing organs and tissues deep inside the human body,enabling non-invasive,rapid diagnosis and treatm...Optical endoscopy has become an essential diagnostic and therapeutic approach in modern biomedicine for directly observing organs and tissues deep inside the human body,enabling non-invasive,rapid diagnosis and treatment.Optical fiber endoscopy is highly competitive among various endoscopic imaging techniques due to its high flexibility,compact structure,excellent resolution,and resistance to electromagnetic interference.Over the past decade,endoscopes based on a single multimode optical fiber(MMF)have attracted widespread research interest due to their potential to significantly reduce the footprint of optical fiber endoscopes and enhance imaging capabilities.In comparison with other imaging principles of MMF endoscopes,the scanning imaging method based on the wavefront shaping technique is highly developed and provides benefits including excellent imaging contrast,broad applicability to complex imaging scenarios,and good compatibility with various well-established scanning imaging modalities.In this review,various technical routes to achieve light focusing through MMF and procedures to conduct the scanning imaging of MMF endoscopes are introduced.The advancements in imaging performance enhancements,integrations of various imaging modalities with MMF scanning endoscopes,and applications are summarized.Challenges specific to this endoscopic imaging technology are analyzed,and potential remedies and avenues for future developments are discussed.展开更多
Radiation-induced attenuation (RIA) in four types of polarization-maintaining optical fibers for interfer-ometric fiberoptic gyroscope (IFOG) at 1310 nm is measured. The measurements are conducted during and after...Radiation-induced attenuation (RIA) in four types of polarization-maintaining optical fibers for interfer-ometric fiberoptic gyroscope (IFOG) at 1310 nm is measured. The measurements are conducted during and after steady-state γ-ray irradiation using a 60 Co source in order to observe significantly different RIA behavior and recovery kinetics. Mechanisms involving dopants and manufacturing process are introduced to analyze the RIA discrepancy as well as to guide the choice and hardening of optical fibers during the design of IFOG. Medium-accuracy IFOG using Ge–F-codoped fiber and pure silica core fiber can survive in the space radiation environment.展开更多
High flatness, wide bandwidth, and high-coherence properties of supercontinuum(SC) generation in fibers are crucial in many applications. It is challenging to achieve SC spectra in a combination of the properties, sin...High flatness, wide bandwidth, and high-coherence properties of supercontinuum(SC) generation in fibers are crucial in many applications. It is challenging to achieve SC spectra in a combination of the properties, since special dispersion profiles are required, especially when pump pulses with duration over 100 fs are employed. We propose an all-solid microstructured fiber composed only of hexagonal glass elements. The optimized fiber possesses an ultraflat all-normal dispersion profile, covering a wide wavelength interval of approximately 1.55 μm. An SC spectrum spanning from approximately 1030 to 2030 nm(corresponding to nearly one octave) with flatness<3 dB is numerically generated in the fiber with 200 fs pump pulses at 1.55 μm. The results indicate that the broadband ultraflat SC sources can be all-fiber and miniaturized due to commercially achievable 200-fs fiber lasers. Moreover, the SC pulses feature high coherence and a single pulse in the time domain, which can be compressed to 13.9-fs pulses with high quality even for simple linear chirp compensation. The Fourier-limited pulse duration of the spectrum is 3.19 fs, corresponding to only 0.62 optical cycles.展开更多
In order to improve the performance of reflectance diffuse optical imaging (rDOI), a novel polynomial geometry (PG) of optical fibers arrangement is proposed. Polynomial geometry is based on the hexagonal geometry...In order to improve the performance of reflectance diffuse optical imaging (rDOI), a novel polynomial geometry (PG) of optical fibers arrangement is proposed. Polynomial geometry is based on the hexagonal geometry (HG) and multicentered double-density (MD) mode. The overlapping sensitivity matrix, area ratio (AR), reconstruction image, two-absorber model, and contrast-to-noise ratio (CNR) in different depths are used to evaluate the performance of PG. The other three geometries including HG, rectangular geometry (RG), and MD mode are also compared with PG. The deformation of the reconstruction images is evaluted by circular ratio (CR). The results prove that the proposed PG has high performance and minimum deformation in quality of reconstruction image in rDOI.展开更多
A new method to determine the radial distribution of attenuation in single-mode optical fibers is proposed. As an example, radiation-induced losses in gamma-irradiated germanosilicate fibers are characterized at 633 nm.
We investigate the temperature dependence of radiation-induced attenuation (RIA) at 1310 nm for a Ge/P co-doped fiber after a steady-state γ-ray irradiation. A V irradiation facility 6^60Co source is used to irradi...We investigate the temperature dependence of radiation-induced attenuation (RIA) at 1310 nm for a Ge/P co-doped fiber after a steady-state γ-ray irradiation. A V irradiation facility 6^60Co source is used to irradiate the fiber at a dose rate of 0.5 Gy/min, satisfying a total dose of 100 Gy. The test temperature ranges from -40 to 60 ℃ by 20 ℃, and the RIA of the fiber is obtained using a power measuring device. The experimental result demonstrates that RIA exhibits a steady, monotonic, and remarkable temperature dependence after approximately 48 h of accelerated annealing at 70 ℃. The optical fiber irradiated with a high dose and annealed sufficiently can be used as a temperature sensor.展开更多
We theoretically analyze and experimentally demonstrate a method of generating equal-amplitude optical comb exploiting multi-frequency phase modulation. The theoretical analysis shows that 4n-1 equalamplitude spectral...We theoretically analyze and experimentally demonstrate a method of generating equal-amplitude optical comb exploiting multi-frequency phase modulation. The theoretical analysis shows that 4n-1 equalamplitude spectral lines can be obtained when the modulation signal comprises n frequency components including the fundamental frequency and the odd harmonic frequencies, and 2n+1 equal-amplitude spectral lines can be obtained when the modulation signal comprises n frequency components including the fundamental frequency and the even harmonic frequencies. Then, we numerically simulate the spectra of 5, 7, 9, and 11 equal-amplitude spectral lines, respectively, which are also obtained in experiments with frequency separation of 30 MHz and flatness of better than 0.3 dB.展开更多
基金We are grateful for financial supports from Special Funds for the Major Fields of Colleges and Universities by the Department of Education of Guangdong Province(2021ZDZX1023)Natural Science Foundation of Guangdong Province(No.2022A1515011434)+4 种基金Stable Support Program for Higher Education Institutions from Shenzhen Science,Technology&Innovation Commission(20200925162216001)Guangdong Basic and Applied Basic Research Foundation(2021B1515120013)Open Fund of State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications,No.IPOC2020A002)The Open Projects Foundation of State Key Laboratory of Optical Fiber and Cable Manufacture Technology(No.SKLD2105)General Program of Shenzhen Science,Technology&Innovation Commission(JCYJ20220530113811026).
文摘Optical fiber technology has changed the world by enabling extraordinary growth in world-wide communications and sensing.The rapid development and wide deployment of optical fiber sensors are driven by their excellent sensing performance with outstanding flexibility,functionality,and versatility.Notably,the research on specialty optical fibers is playing a critical role in enabling and proliferating the optical fiber sensing applications.This paper overviews recent developments in specialty optical fibers and their sensing applications.The specialty optical fibers are reviewed based on their innovations in special structures,special materials,and technologies to realize lab in/on a fiber.An overview of sensing applications in various fields is presented.The prospects and emerging research areas of specialty optical fibers are also discussed.
文摘New types of communication cables were found to be needed already during the 1960-decade,because the copper cables had,and still would have,too high attenuation and especially limited bandwidth,due to extremely high dispersion at communication signals above 2 Mbit/s.Already the first commercially available multimode optical fibers(1979),developed from pure silica glass with a Ge-doped core,had much lower attenuation at signal frequencies of the order of 2-9 Mbit/s and above it.However,fiber core,cladding and coating materials,cable structures and materials,as well as manufacturing-,measurements-and test methods have been needed to be developed much further to get the reliable fiber cable communication networks.The important development stages and solutions to the most significant childhood problems of the optical fibers and cables are described in this paper.Now over 500 million km of optical fibers are manufactured and installed worldwide for the communication networks.The understanding of how to make the fibers with the very good transmission,mechanical and reliability properties exists at the manufacturers of the fibers and cables.
基金National Natural Science Foundation of China(Nos.61871353,62031005)。
文摘In-situ measurement of internal solitary waves(ISWs)is complicated in the ocean due to their randomness.At present,the ISWs are mainly detected by the chain structure of conductivity-temperature-depth systems(CTDs)or temperature sensors.The high cost limits the spatial resolution,which ultimately affects the measuring accuracy of the ISW amplitude.In this paper,we developed an experimental measurement system for detecting ISWs based on the stimulated Raman scattering in distributed optical fibers.This system has the advantages of high precision,low cost,and easy operation.The experimental results show that the system is consistent with CTDs in the measurement of vertical ocean temperature variation.The spatial resolution of the system can reach 1.0 m and the measuring accuracy of temperature is 0.2℃.We successfully detected 3 ISWs by the system in the South China Sea and two optical remote sensing images collected on May 18,2021,the same day of two detected ISWs,verify the occurrence of the measured ISWs.We used the image pairs method to calculate the phase velocity of ISW and the result is 1.71 ms^(-1).By extracting the distances between wave packets,it can be found that the semi-diurnal tide generates the detected ISWs.The impact of the tidal current velocity on the ISW in amplitude is undeniable.Undoubtedly,the system has a great application prospect for detecting ISWs and other dynamic phenomena in the ocean.
基金Project supported by the Natural Science Foundation of Jiangsu Provincial Universities(Grant No.14KJB140009)the National Natural Science Foundation of China(Grant No.11447113)the Startup Foundation for Introducing Talent of NUIST(Grant No.2241131301064)
文摘Modulation instabilities in the randomly birefringent two-mode optical fibers (RB-TMFs) are analyzed in detail by accounting the effects of the differential mode group delay (DMGD) and group velocity dispersion (GVD) ratio between the two modes, both of which are absent in the randomly birefringent single-mode optical fibers (RB-SMFs). New MI characteristics are found in both normal and anomalous dispersion regimes. For the normal dispersion, without DMGD, no MI exists. With DMGD, a completely new MI band is generated as long as the total power is smaller than a critical total power value, named by Per, which increases significantly with the increment of DMGD, and reduces dramatically as GVD ratio and power ratio between the two modes increases. For the anomalous dispersion, there is one MI band without DMGD. In the presence of DMGD, the MI gain is reduced generally. On the other hand, there also exists a critical total power (Per), which increases (decreases) distinctly with the increment of DMGD (GVD ratio of the two modes) but varies complicatedly with the power ratio between the two modes. Two MI bands are present for total power smaller than Per, and the dominant band can be switched between the low and high frequency bands by adjusting the power ratio between the two modes. The M1 analysis in this paper is verified by numerical simulation.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11604230 and 11434017)the Guangdong Provincial Innovative and Entrepreneurial Research Team Program,China(Grant No.2016ZT06C594)the National Key Research and Development Program of China(Grant No.2018YFA 0306200)
文摘We investigate the microscopic optical force density distributions respectively inside a subwavelength-diameter(SD)fiber with flat endface and inside one with oblique endface by using a finite-difference time-domain(FDTD) method.Optical force density distributions at the fiber endfaces can now be readily available. The complete knowledge of optical force density distributions not only reveal features regarding the microscopic near-field optomechanical interaction, but also provide straightforward explanations for the sideway deflections and other mechanical motions. Our results can provide a useful reference for better understanding the mechanical influence when light transports in a microscale or nanoscale structure and for developing future highly-sensitive optomechanical devices.
基金Project supported by the National Natural Science Foundation of China (Grant No. 61007040)
文摘In order to analyze the effect of wavelength-dependent radiation-induced attenuation (RIA) on the mean trans- mission wavelength in optical fiber and the scale factor of interferometric fiber optic gyroscopes (IFOGs), three types of polarization-maintaining (PM) fibers are tested by using a 60Co γ-radiation source. The observed different mean wave- length shift (MWS) behaviors for different fibers are interpreted by color-center theory involving dose rate-dependent absorption bands in ultraviolet and visible ranges and total dose-dependent near-infrared absorption bands. To evaluate the mean wavelength variation in a fiber coil and the induced scale factor change for space-borne IFOGs under low radiation doses in a space environment, the influence of dose rate on the mean wavelength is investigated by testing four germanium (Ge) doped fibers and two germanium-phosphorus (Ge-P) codoped fibers irradiated at different dose rates. Experimental results indicate that the Ge-doped fibers show the least mean wavelength shift during irradiation and their mean wavelength of optical signal transmission in fibers will shift to a shorter wavelength in a low-dose-rate radiation environment. Finally, the change in the scale factor of IFOG resulting from the mean wavelength shift is estimated and tested, and it is found that the significant radiation-induced scale factor variation must be considered during the design of space-borne IFOGs.
基金supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry,China
文摘The effects of color centers' absorption on fibers and interferometric fiber optical gyroscopes(IFOGs) are studied in the paper. The irradiation induced attenuation(RIA) spectra of three types of polarization-maintaining fibers(PMFs), i.e.,P-doped, Ge-doped, and pure silica, irradiated at 100 Gy and 1000 Gy are measured in a wavelength range from 1100 nm to1600 nm and decomposed according to the Gaussian model. The relationship of the color centers absorption intensity with radiation dose is investigated based on a power model. Furthermore, the effects of all color centers' absorption on RIA and mean wavelength shifts(MWS) at 1300 nm and 1550 nm are discussed respectively. Finally, the random walk coefficient(RWC) degradation induced from RIA and the scale factor error induced by MWS of the IFOG are simulated and tested at a wavelength of 1300 nm. This research will contribute to the applications of the fibers in radiation environments.
基金Project supported by the Shanghai Leading Academic Discipline Project (Grant No.S30108)the Science and Technology Commission of Shanghai Municipality (Grant No.08DZ2231100)
文摘Stress-induced birefringence and modal birefringence of single-mode specialty optical fibers with three stress regions are numerically analyzed by the vector finite element method. Stress distribution and stress-induced birefringence distribution of three kinds of optical fibers with different cross structures are presented and compared, and the influence on the stress- induced birefringence by temperature change are analyzed as well. The results show that the fibers with three-stress regions have a lower linear birefringence, which is very important for the fabrication of the circular polaxization-maintalning fiber with high performance drawn from the same fiber preform by using the spinning method.
基金Project supported by the National Natural Science Foundation of China(Grant No.61271030)
文摘Many experimental investigations on the temperature dependence of the refractive index of optical fibers have been reported previously, however a satisfying theoretical explanation for it is still absent. In this paper, a theoretical model about the temperature dependence of the refractive index of optical fibers is presented and it is in agreement with the previous experimental results. This work is a significant reference for the research and development of temperature sensors based on optical fiber delay lines.
基金Supported by the National Basic Research Program of China ( "973" Program) ( 2011 CB013000 ) the National Natural Sci- ence Foundation of China (NSFC) ( 90923039 51105038)
文摘A simple fiber sensor to measure angular displacement with high resolution, which is based on whispering gallery mode (WGM) resonance in bent optical fibers,is proposed. The sensor is composed of a single loop formed by loosely tying a knot using single mode fiber. To measure the transmission spectra, a tunable laser and an optic power meter are connected to the two ends of fi- ber loop, respectively. Significant WGM resonances occur over the investigated wavelength range for all the sensors with different bend radius. The angular-displacement sensitivity is studied in the range from -0. 1°to 0. 1°. The detection limit of 1.49 × 10 ^-7 rad can be achieved for the detecting system with the resolution of lpm. The simple loop-structure fiber sensor has potential application prospect in the field of architecture or bridge building with low detection limit and low cost.
文摘We propose an alternative approach to compensation of intermodal interactions in few-mode optical fibers by means of digital backpropagation.Instead of solving the inverse generalized multimode nonlinear Schr?dinger equation,we accomplish backpropagation of the multimode signals with help of their near-field intensity distributions captured by a camera.We demonstrate that this task can successfully be handled by a deep neural network and provide a proof of concept by training an autoencoder for backpropagation of six linearly polarized[LP]modes of a step-index fiber.
基金Funded by National Natural Science Foundation of China (Nos.51372179, 51772224)the Open Projects Foundation of Yangtze Optical Fiber and Cable Joint Stock Limited Company (YOFC)(No.SKLD1705)。
文摘The surface-enhanced Raman scattering(SERS) optical fiber probes were successfully prepared by self-assembling on polyelectrolyte multilayers. Gold nanorods(Au NRs) were used as SERS enhancement material to give excellent biological affinity and stability to the SERS optical fiber probes. Au NRs were synthesized by seed growth method. The synergistic effect between AgNO_(3) and surfactant was investigated, and the highest yield was found when AgNO_(3) was 500 uL. Meanwhile, different SERS optical fiber probes were obtained by selecting silane coupling agent, polyelectrolyte multilayer and graphene oxide(GO) to treat quartz fiber. It was found that the SERS optical fiber probes obtained by the self-assembled on polyelectrolyte multilayers method performed better than those by other methods. In addition, Mapping was combined with finite element simulation to analyze the electromagnetic field distribution at the fiber end face.The electromagnetic field distribution of Au NRs was investigated, the difference of electromagnetic field intensity around the Au NRs with different arrangements was compared, the strongest signal was obtained when the Au NRs were head-to-head. Finally, sensitivity of the optimized SERS optical fiber probes could reach 10^(-9)mol/L, with excellent stability and repeatability.
基金the National Natural Science Foundation of China(No.52307245[Y.D.Li],No.U21A20170[X.He],22279070[L.Wang],and 52206263[Y.Song])the China Postdoctoral Science Foundation(No.2022M721820[Y.D.Li])the Ministry of Science and Technology of China(No.2019YFA0705703[L.Wang])。
文摘The battery technology progress has been a contradictory process in which performance improvement and hidden risks coexist.Now the battery is still a“black box”,thus requiring a deep understanding of its internal state.The battery should“sense its internal physical/chemical conditions”,which puts strict requirements on embedded sensing parts.This paper summarizes the application of advanced optical fiber sensors in lithium-ion batteries and energy storage technologies that may be mass deployed,focuses on the insights of advanced optical fiber sensors into the processes of one-dimensional nano-micro-level battery material structural phase transition,electrolyte degradation,electrode-electrolyte interface dynamics to three-dimensional macro-safety evolution.The paper contributes to understanding how to use optical fiber sensors to achieve“real”and“embedded”monitoring.Through the inherent advantages of the advanced optical fiber sensor,it helps clarify the battery internal state and reaction mechanism,aiding in the establishment of more detailed models.These advancements can promote the development of smart batteries,with significant importance lying in essentially promoting the improvement of system consistency.Furthermore,with the help of smart batteries in the future,the importance of consistency can be weakened or even eliminated.The application of advanced optical fiber sensors helps comprehensively improve the battery quality,reliability,and life.
基金supported by National Natural Science Foundation of China(62135007 and 61925502).
文摘Optical endoscopy has become an essential diagnostic and therapeutic approach in modern biomedicine for directly observing organs and tissues deep inside the human body,enabling non-invasive,rapid diagnosis and treatment.Optical fiber endoscopy is highly competitive among various endoscopic imaging techniques due to its high flexibility,compact structure,excellent resolution,and resistance to electromagnetic interference.Over the past decade,endoscopes based on a single multimode optical fiber(MMF)have attracted widespread research interest due to their potential to significantly reduce the footprint of optical fiber endoscopes and enhance imaging capabilities.In comparison with other imaging principles of MMF endoscopes,the scanning imaging method based on the wavefront shaping technique is highly developed and provides benefits including excellent imaging contrast,broad applicability to complex imaging scenarios,and good compatibility with various well-established scanning imaging modalities.In this review,various technical routes to achieve light focusing through MMF and procedures to conduct the scanning imaging of MMF endoscopes are introduced.The advancements in imaging performance enhancements,integrations of various imaging modalities with MMF scanning endoscopes,and applications are summarized.Challenges specific to this endoscopic imaging technology are analyzed,and potential remedies and avenues for future developments are discussed.
基金supported by the National Natural Science Foundation of China under Grant No. 61007040
文摘Radiation-induced attenuation (RIA) in four types of polarization-maintaining optical fibers for interfer-ometric fiberoptic gyroscope (IFOG) at 1310 nm is measured. The measurements are conducted during and after steady-state γ-ray irradiation using a 60 Co source in order to observe significantly different RIA behavior and recovery kinetics. Mechanisms involving dopants and manufacturing process are introduced to analyze the RIA discrepancy as well as to guide the choice and hardening of optical fibers during the design of IFOG. Medium-accuracy IFOG using Ge–F-codoped fiber and pure silica core fiber can survive in the space radiation environment.
基金National Natural Science Foundation of China(NSFC)(61475171,11374084,61705244,61307056)Natural Science Foundation of Shanghai(17ZR1433900,17ZR1434200)
文摘High flatness, wide bandwidth, and high-coherence properties of supercontinuum(SC) generation in fibers are crucial in many applications. It is challenging to achieve SC spectra in a combination of the properties, since special dispersion profiles are required, especially when pump pulses with duration over 100 fs are employed. We propose an all-solid microstructured fiber composed only of hexagonal glass elements. The optimized fiber possesses an ultraflat all-normal dispersion profile, covering a wide wavelength interval of approximately 1.55 μm. An SC spectrum spanning from approximately 1030 to 2030 nm(corresponding to nearly one octave) with flatness<3 dB is numerically generated in the fiber with 200 fs pump pulses at 1.55 μm. The results indicate that the broadband ultraflat SC sources can be all-fiber and miniaturized due to commercially achievable 200-fs fiber lasers. Moreover, the SC pulses feature high coherence and a single pulse in the time domain, which can be compressed to 13.9-fs pulses with high quality even for simple linear chirp compensation. The Fourier-limited pulse duration of the spectrum is 3.19 fs, corresponding to only 0.62 optical cycles.
基金supported by the National Natural Science Foundation of China(No.30671997)the National "863" Program of China(No.2008AA02Z438).
文摘In order to improve the performance of reflectance diffuse optical imaging (rDOI), a novel polynomial geometry (PG) of optical fibers arrangement is proposed. Polynomial geometry is based on the hexagonal geometry (HG) and multicentered double-density (MD) mode. The overlapping sensitivity matrix, area ratio (AR), reconstruction image, two-absorber model, and contrast-to-noise ratio (CNR) in different depths are used to evaluate the performance of PG. The other three geometries including HG, rectangular geometry (RG), and MD mode are also compared with PG. The deformation of the reconstruction images is evaluted by circular ratio (CR). The results prove that the proposed PG has high performance and minimum deformation in quality of reconstruction image in rDOI.
文摘A new method to determine the radial distribution of attenuation in single-mode optical fibers is proposed. As an example, radiation-induced losses in gamma-irradiated germanosilicate fibers are characterized at 633 nm.
基金supported by the National Natural Sci-ence Foundation of China(No.61007040)
文摘We investigate the temperature dependence of radiation-induced attenuation (RIA) at 1310 nm for a Ge/P co-doped fiber after a steady-state γ-ray irradiation. A V irradiation facility 6^60Co source is used to irradiate the fiber at a dose rate of 0.5 Gy/min, satisfying a total dose of 100 Gy. The test temperature ranges from -40 to 60 ℃ by 20 ℃, and the RIA of the fiber is obtained using a power measuring device. The experimental result demonstrates that RIA exhibits a steady, monotonic, and remarkable temperature dependence after approximately 48 h of accelerated annealing at 70 ℃. The optical fiber irradiated with a high dose and annealed sufficiently can be used as a temperature sensor.
基金supported by the China Postdoctoral Science Foundation(No.20060400230)the Foundation for Innovation Talents by the Technology Ministry of Harbin(No.2006RFQXG025)
文摘We theoretically analyze and experimentally demonstrate a method of generating equal-amplitude optical comb exploiting multi-frequency phase modulation. The theoretical analysis shows that 4n-1 equalamplitude spectral lines can be obtained when the modulation signal comprises n frequency components including the fundamental frequency and the odd harmonic frequencies, and 2n+1 equal-amplitude spectral lines can be obtained when the modulation signal comprises n frequency components including the fundamental frequency and the even harmonic frequencies. Then, we numerically simulate the spectra of 5, 7, 9, and 11 equal-amplitude spectral lines, respectively, which are also obtained in experiments with frequency separation of 30 MHz and flatness of better than 0.3 dB.