We propose and demonstrate a passively mode-locked erbium-doped fiber laser(EDFL)based on zinc-oxide/polydimethylsiloxane(ZnO/PDMS)saturable absorber(SA)that evanescently interacts with the light on a tapered fiber.Th...We propose and demonstrate a passively mode-locked erbium-doped fiber laser(EDFL)based on zinc-oxide/polydimethylsiloxane(ZnO/PDMS)saturable absorber(SA)that evanescently interacts with the light on a tapered fiber.The ZnO/PDMS composite is coated on the whole surface of the tapered fiber to guarantee the maximum efficiency of the SA device,with a measured insertion loss of 0.87 dB and a modulation depth of 6.4%.The proposed laser can generate soliton mode-locking operation at a threshold power of 33.07 mW.The generated output pulse yields a repetition rate and pulse width of 9.77 MHz and 1.03 ps,respectively.These results indicate that the proposed ZnO/PDMS-clad tapered fiber could be useful as an efficient,compatible,and low-cost SA device for ultrafast laser applications.展开更多
Objective: To establish a DNA detection platform based on a tapered optical fiber to detect Leptospira DNA by targeting the leptospiral secY gene.Methods: The biosensor works on the principle of light propagating in t...Objective: To establish a DNA detection platform based on a tapered optical fiber to detect Leptospira DNA by targeting the leptospiral secY gene.Methods: The biosensor works on the principle of light propagating in the special geometry of the optical fiber tapered from a waist diameter of 125 to 12 μm. The fiber surface was functionalized through a cascade of chemical treatments and the immobilization of a DNA capture probe targeting the secY gene. The presence of the target DNA was determined from the wavelength shift in the optical transmission spectrum.Results: The biosensor demonstrated good sensitivity, detecting Leptospira DNA at 0.001 ng/μL, and was selective for Leptospira DNA without cross-reactivity with non-leptospiral microorganisms. The biosensor specifically detected DNA that was specifically amplified through the loop-mediated isothermal amplification approach.Conclusions: These findings warrant the potential of this platform to be developed as a novel alternative approach to diagnose leptospirosis.展开更多
We report on the optical trapping and orientation of Escherichia coli(E.coli) cells using two tapered fiber probes.With a laser beam at 980 nm wavelength launched into probe I, an E. coli chain consisting of three cel...We report on the optical trapping and orientation of Escherichia coli(E.coli) cells using two tapered fiber probes.With a laser beam at 980 nm wavelength launched into probe I, an E. coli chain consisting of three cells was formed at the tip of probe I. After launching a beam at 980 nm into probe II, the E.coli at the end of the chain was trapped and oriented via the optical torques yielded by two probes. The orientation of the E. coli was controlled by adjusting the laser power of probe II. Experimental results were interpreted by theoretical analysis and numericalsimulations.展开更多
Pumping combiner is a kernel component of high power fiber laser (HPFL). We demonstrate two types of tapered fiber bundle (TFB) end-pumping combiner able to combining multi-kilowatts of pumping laser. After the ex...Pumping combiner is a kernel component of high power fiber laser (HPFL). We demonstrate two types of tapered fiber bundle (TFB) end-pumping combiner able to combining multi-kilowatts of pumping laser. After the experimental test of coupling performance, the 3xl coupler is proved to have a power handling capacity of 2.11 kW with a coupling efficiency of 95.1%, and the 7× 1 coupler is capable of handling pumping power of 4.72 kW with a coupling efficiency of 99.4%. These two coupler have obtained the ability to be used in laser diodes (LDs) direct beam combining and the pumping coupling of multikilowatts level fiber lasers.展开更多
Deposition of two-dimensional(2D) MoS2 materials on the tapered fiber allows various photonic applications including saturable absorbers and four-wave mixing.Ethanol catalytic deposition(ECD) of MoS2 on the optica...Deposition of two-dimensional(2D) MoS2 materials on the tapered fiber allows various photonic applications including saturable absorbers and four-wave mixing.Ethanol catalytic deposition(ECD) of MoS2 on the optical tapered fiber was proposed and demonstrated in this work.Different from the conventional optical driven deposition using water or organic solvent,the ECD method utilized the high volatility of the ethanol solvent,which significantly increased the movement speed of the MoS2 nanosheets and thus boosted the deposition rate and reduced the minimum power threshold to drive the deposition.We believe the ECD method should be able to be applied to other similar 2D materials such as other types of transition metal chalcogenides.展开更多
A sensitive tapered optical fiber sensor incorporating graphene oxide(GO)and polyvinyl alcohol(PVA)composite film for the rapid measurement of changes in relative humidity was proposed and experimentally demonstrated....A sensitive tapered optical fiber sensor incorporating graphene oxide(GO)and polyvinyl alcohol(PVA)composite film for the rapid measurement of changes in relative humidity was proposed and experimentally demonstrated.The sensing principle was based on the intensity modulation of the transmitted light induced by the refractive index changes of the sensitive coatings.The sensing region was obtained by tapering a section of single-mode optical fiber(SMF)from its original 125µm diameter down to 9.03µm.The tapered structure was then modified through deposition of GO/PVA nanocomposites by using the dip-coating technique.The field emission scanning electron microscope(FESEM)and Raman spectroscopy were used to characterize the structure of the composite film.As evidenced by a Fourier transform infrared spectroscopy(FTIR)analysis,the presence of oxygen functional groups(such as−OH and COOH)on the GO structure enabled the attachment of PVA molecules through hydrogen bonding and strong adhesion between GO/PVA layers.The performance of the sensor was tested over a wide range(20%RH to 99.9%RH)of relative humidity.The sensor showed a good response with its signal increasing linearly with the surrounding humidity.The tapered optical fiber sensor with the coating of GO/0.3g PVA achieved the highest sensitivity[0.5290RH(%)].The stability,repeatability,reversibility,as well as response time of the designated sensor were also measured and analyzed.展开更多
A temperature sensor is demonstrated and fabricated by coating the single-mode tapered optical fiber with temperature-sensitive silicone rubber. It works on the change of the evanescent fields in the tapered optical f...A temperature sensor is demonstrated and fabricated by coating the single-mode tapered optical fiber with temperature-sensitive silicone rubber. It works on the change of the evanescent fields in the tapered optical fiber. Small changes in the refractive index of coating film greatly influence the power of evanescent fields, which modulate the transmission optical power in the waist region. The range of temperature measured is from -20℃ to 70 ℃. The results show that the temperature sensor has high temperature sensitivity (0.012 mW/℃) and good repeatability.展开更多
We demonstrate a stable Yb:fiber frequency comb with supercontinuum generation by using a specially designed tapered single-mode fiber, in which a spectrum spanning from 500 nm to 1500 nm is produced. The carrier-env...We demonstrate a stable Yb:fiber frequency comb with supercontinuum generation by using a specially designed tapered single-mode fiber, in which a spectrum spanning from 500 nm to 1500 nm is produced. The carrier-envelope offset signal of the Yb:fiber comb is measured with a signal-to-noise ratio of more than 40 dB and a linewidth narrower than 120 kHz. The repetition rate and carrier-envelope offset signals are simultaneously phase locked to a microwave reference frequency.展开更多
In this paper, a novel surface-enhanced Raman scattering (SERS) sensor combined with fused biconical taper fiber (FBTF) and film coated with silver sols is proposed. This structure is designed to significantly inc...In this paper, a novel surface-enhanced Raman scattering (SERS) sensor combined with fused biconical taper fiber (FBTF) and film coated with silver sols is proposed. This structure is designed to significantly increase the SERS active surface when the length of the taper is increased and the radius is reduced, since the penetration depth is inversely proportional to the taper radius and proportional to the taper length according to the fiber-optic evanescent-wave theory. Based on the SERS sensing principle, the feasibility of FBTF sensor is analyzed in this paper. As a result, the Raman spectrum of R6G is obtained from the fused biconical taper zone surface coating with the silver sols in our experiments. The detected concentration is up to 10-7mol/L.展开更多
A kind of tapered segmented cladding fiber(T-SCF)with large mode area(LMA)is proposed,and the mode and amplification characteristics of T-SCFs with concave,linear,and convex tapered structures are investigated based o...A kind of tapered segmented cladding fiber(T-SCF)with large mode area(LMA)is proposed,and the mode and amplification characteristics of T-SCFs with concave,linear,and convex tapered structures are investigated based on finite-element method(FEM)and few-mode steady-state rate equation.Simulation results indicate that the concave tapered structure can introduce high loss for high-order modes(HOMs)that is advantageous to achieve single-mode operation,whereas the convex tapered structure provides large effective mode area that can help to mitigate nonlinear effects.Meanwhile,the small-to-large amplification scheme shows further advantages on stripping off HOMs,and the large-to-small amplification scheme decreases the heat load density induced by the high-power pump.Moreover,singlemode propagation performance,effective mode area,and heat load density of the T-SCF are superior to those of tapered step index fiber(T-SIF).These theoretical model and numerical results can provide instructive suggestions for designing high-power fiber lasers and amplifiers.展开更多
We present a new procedure for protecting micro-optical fibers(tapered fibers)by using the 3-dimensional(3D)printing technology.A standard single-mode optical fiber was tapered down to the diameter of 1mm and embedded...We present a new procedure for protecting micro-optical fibers(tapered fibers)by using the 3-dimensional(3D)printing technology.A standard single-mode optical fiber was tapered down to the diameter of 1mm and embedded in a polymeric matrix obtained by an additive manufacturing routine.We show that the proposed structure protects the fiber taper against environmental humidity while keeping permeability to gas flow and the possibility of the realization of gas detection experiments.To our knowledge,this is the first time 3D printed casings were applied to protect fiber tapers from humidity deterioration.We envisage this new approach will allow the development of new fiber taper devices to better resist in humid environments.展开更多
The ascorbic acid(AA)is a biomarker that can be used to detect the symptoms of severe disorders such as scurvy,Parkinson’s,Alzheimer’s,and cardiovascular diseases.In this work,a simple and effective sensor model is ...The ascorbic acid(AA)is a biomarker that can be used to detect the symptoms of severe disorders such as scurvy,Parkinson’s,Alzheimer’s,and cardiovascular diseases.In this work,a simple and effective sensor model is developed to diagnose the presence of AA samples.To develop the sensor,a tapered single-mode optical fiber has been used with the well-known phenomenon of localized surface plasmon resonance(LSPR).For LSPR,the tapered region is immobilized with synthesized gold nanoparticles(AuNPs)and zinc oxide nanoparticles(ZnO-NPs)whose absorbance peak wavelengths appear at 519nm and 370nm,respectively.On the basis of nanoparticles(NPs)configurations,two different biosensor probes are developed.In the first one,the sensing region is immobilized with AuNPs and named Probe I.In the second probe,the immobilized layer of AuNPs is further coated with a layer of ZnO-NPs,and a resultant probe is termed as Probe II.The characterizations of synthesized AuNPs and developed fiber probes are done by the ultraviolet-visible(UV-vis)spectrophotometer,high-resolution transmission electron microscope(HR-TEM),atomic force microscopy(AFM),and scanning electron microscope(SEM).To enhance the selectivity,a sensing region of probes is functionalized with ascorbate oxidase enzyme that oxidizes the AA in the presence of oxygen.The response of developed sensor probes is authenticated by sensing the samples of AA in the range from 500 nM to 1 mM,which covers the range of AA found in human bodies,i.e.,40μM-120μM.The performance analysis of the developed sensor probes has been done in terms of their stability,reproducibility,reusability,and selectivity.To observe the stability of AA,a pH-test has also been done that results in a better solubility of AA molecules in phosphate-buffered saline(PBS)solution.展开更多
A rapid and high-performance sensor for lard adulterant in edible oil was developed using the tapered plastic optical fiber(POF)coated with graphene and multi-walled carbon nanotubes.The coating material was deposited...A rapid and high-performance sensor for lard adulterant in edible oil was developed using the tapered plastic optical fiber(POF)coated with graphene and multi-walled carbon nanotubes.The coating material was deposited onto a tapered POF with a taper waist diameter and a taper length of 0.45 mm and 1 cm,respectively.The addition of the coating material was used to increase the sensitivity and selectivity coefficient of the tapered POF toward the lard substance.The sensing mechanism is based on a simultaneous interaction of lard substance and an evanescent wave of tapered POF with the coating layers.The results showed that graphene coating on the tapered POF increased the selectivity coefficient of the tapered POF towards lard substance from 33.54 to 324.19,and it gave a sensitivity of 0.427 dBm/%.In comparison,multi-walled carbon nanotubes coating increased the selectivity coefficient to 71.65 and increased its sensitivity to 1.189 dBm/%.Thus,the proposed configuration of the tapered POF with the coating material offered a simple configuration for a rapid,high sensitivity and selectivity detection of lard adulterant in edible oils.展开更多
An evanescent wave absorption (EWA) sensor based tapered plastic optical fiber (TPOF) coated with monolayer graphene film for ethanol molecules detection is demonstrated in this study. The continuous and monolayer...An evanescent wave absorption (EWA) sensor based tapered plastic optical fiber (TPOF) coated with monolayer graphene film for ethanol molecules detection is demonstrated in this study. The continuous and monolayer graphene films were grown on a Cu foil by using chemical vapor deposition (CVD) technology. Polymethyl methacrylate (PMMA) was used as the carrier to support the transfer of graphene from Cu foil to the skinless tapered optical fiber core. The accuracy of the TPOF sensor with graphene (G-TPOF sensor) is much higher than that without gra- phene (TPOF sensor), which can be attributed to the molecules enriched on the surface of graphene. The absorbance (A) and the concentrations of ethanol solution show an excellent proportional relationship in a range of 0--100%. The dynamic response of the G-TPOF sensor has shown strong reversibility, repeatability and stability at room temperature. The response time and recovery time of the G-TPOF sensor for different concentrations are all less than 30 s. Beyond that, we selected the Chinese liquor as the analyte, and the results are consistent with the concen- tration-list obtained in the experiment.展开更多
A simple structure optical fiber sensor for relative humidity(RH) and temperature measurement is proposed and verified in this paper, which is based on graphene oxide quantum dots and polyvinyl alcohol(GOQDs-PVA) comp...A simple structure optical fiber sensor for relative humidity(RH) and temperature measurement is proposed and verified in this paper, which is based on graphene oxide quantum dots and polyvinyl alcohol(GOQDs-PVA) composite coated tapered no-core fiber(NCF) combined with a fiber Bragg grating(FBG). FBG is insensitive to humidity and sensitive to temperature, which is used to compensate temperature of the sensor. Experimental results show this sensor has humidity sensitivity of 143.27 pm/%RH ranging from 30%RH to 80%RH and the temperature sensitivity of 9.21 pm/℃. The proposed sensor has advantages of simple structure, good repeatability, and good stability, which is expected to be used in both RH and temperature measurement in biological and chemical fields.展开更多
Core mode cutoff is a useful concept not only for a tapered single-core fiber(SCF) but also for a tapered multicore fiber(MCF) to realize cladding mode transmission. In this paper, cut-off conditions of either core mo...Core mode cutoff is a useful concept not only for a tapered single-core fiber(SCF) but also for a tapered multicore fiber(MCF) to realize cladding mode transmission. In this paper, cut-off conditions of either core mode for tapered SCFs or supermodes for MCFs are theoretically investigated. Rigorous analytical formulas are derived for the modes of SCF by a three-layer waveguide model, and an approximation formula of the cut-off condition is given for the LP01 mode. The supermodes of MCFs are analyzed by the coupling mode theory, and the cut-off condition is calculated by a numerical method. Simulation results show that the in-phase supermode of MCFs has a similar cut-off condition with that of SCF. Based on this property, a convenient approximate formula is given to estimate the cut-off condition of the in-phase supermode for tapered MCFs.展开更多
As a low-dimensional optical fiber with diameter close to or below the wavelength of light,optical micro/nanofiber(MNF)offers a number of favorable properties for optical sensing,which have been exploited in a variety...As a low-dimensional optical fiber with diameter close to or below the wavelength of light,optical micro/nanofiber(MNF)offers a number of favorable properties for optical sensing,which have been exploited in a variety of sensing applications,including physical,chemical,and biological sensors.In this paper we review the principles and applications of silica,glass,and polymer optical micro/nanofibers for physical and chemical sensing.展开更多
The thin, long length and high smoothness silica photonic nanowires and taper optical fiber were fabricated using a simple and low cost chemical etching method. A two-steps wet etch process were used consisting of etc...The thin, long length and high smoothness silica photonic nanowires and taper optical fiber were fabricated using a simple and low cost chemical etching method. A two-steps wet etch process were used consisting of etching with 30% HF acid to remove cladding and 24% HF acid to decrease fiber core diameter. An approach for on-line monitoring of etching using 1300 nm light power transmitted in the optical fiber was used to determine the diameter of the remaining core and showed a transition between two different operation regimes of nanofiber from the embedded regime, where the mode was isolated from the environment, to the evanescent regime. The data indicated that the diameter of the silica fiber decreased linearly for both 30% and 24% HF acid with 1.2 and 0.1/zm/min grad diameter, respectively at room temperature, and more than 70% of the mode intensity could propagate outside fiber when the core diameter was less than 1μm. The results of fiber taper showed that the fiber was tapered by a factor of 20 while retaining a thin core structure and leaving about more than 85% of core structure.展开更多
This Letter presents intrinsic Fabry–Perot interferometers in the fiber tapers fabricated by the femtosecond laser micromachining technique. The sensing of temperatures as high as 1000°C based on the fiber devic...This Letter presents intrinsic Fabry–Perot interferometers in the fiber tapers fabricated by the femtosecond laser micromachining technique. The sensing of temperatures as high as 1000°C based on the fiber device is characterized, with a sensitivity of 15.28 pm∕°C. A nearly linear refractive index sensing is also obtained by using the fringe visibility to characterize, with a sensitivity of 73.05 dB∕RIU. These intrinsic Fabry–Perot interferometers in fiber tapers may be useful in applications of high-temperature and linear refractive index sensing.展开更多
A modal interferometer is experimentally demonstrated based on tapering a single-mode-multimode-single- mode (SMS) fiber structure heated by hydrogen flame. The interference fringe begins to form when tapering lengt...A modal interferometer is experimentally demonstrated based on tapering a single-mode-multimode-single- mode (SMS) fiber structure heated by hydrogen flame. The interference fringe begins to form when tapering length is 19.8 mm, and becomes regular and clear when the tapering length is longer and the tapered waist diameter is smaller. Annealing process is undertaken to achieve a high extension ratio of approximately 17 dB with free spectral range of 1.5 nm when the tapering length is 33 mm and the tapered waist diameter is approximately 5 μm. The temperature and axial strain dependences of the tapered SMS structure are characterized, and the measured temperature and strain coefficients are +7 pm/℃ and -9.536 pm/με, respectively.展开更多
基金the Ministry of Higher Education of Malaysia(MOHE)(Grant No.FRGS/1/2019/STG02/UPM/02/4).
文摘We propose and demonstrate a passively mode-locked erbium-doped fiber laser(EDFL)based on zinc-oxide/polydimethylsiloxane(ZnO/PDMS)saturable absorber(SA)that evanescently interacts with the light on a tapered fiber.The ZnO/PDMS composite is coated on the whole surface of the tapered fiber to guarantee the maximum efficiency of the SA device,with a measured insertion loss of 0.87 dB and a modulation depth of 6.4%.The proposed laser can generate soliton mode-locking operation at a threshold power of 33.07 mW.The generated output pulse yields a repetition rate and pulse width of 9.77 MHz and 1.03 ps,respectively.These results indicate that the proposed ZnO/PDMS-clad tapered fiber could be useful as an efficient,compatible,and low-cost SA device for ultrafast laser applications.
基金funded by Universiti Putra Malaysia through the Geran Inisiatif Putra Siswazah (GP-IPS/2019/9678200)。
文摘Objective: To establish a DNA detection platform based on a tapered optical fiber to detect Leptospira DNA by targeting the leptospiral secY gene.Methods: The biosensor works on the principle of light propagating in the special geometry of the optical fiber tapered from a waist diameter of 125 to 12 μm. The fiber surface was functionalized through a cascade of chemical treatments and the immobilization of a DNA capture probe targeting the secY gene. The presence of the target DNA was determined from the wavelength shift in the optical transmission spectrum.Results: The biosensor demonstrated good sensitivity, detecting Leptospira DNA at 0.001 ng/μL, and was selective for Leptospira DNA without cross-reactivity with non-leptospiral microorganisms. The biosensor specifically detected DNA that was specifically amplified through the loop-mediated isothermal amplification approach.Conclusions: These findings warrant the potential of this platform to be developed as a novel alternative approach to diagnose leptospirosis.
基金supported by the Program for Changjiang Scholars and Innovative Research Team in University (IRT13042)the National Natural Science Foundation of China (No. 61205165)
文摘We report on the optical trapping and orientation of Escherichia coli(E.coli) cells using two tapered fiber probes.With a laser beam at 980 nm wavelength launched into probe I, an E. coli chain consisting of three cells was formed at the tip of probe I. After launching a beam at 980 nm into probe II, the E.coli at the end of the chain was trapped and oriented via the optical torques yielded by two probes. The orientation of the E. coli was controlled by adjusting the laser power of probe II. Experimental results were interpreted by theoretical analysis and numericalsimulations.
基金This work was supported in part by the National Natural Science Foundation of China (Grant No. 61307057).
文摘Pumping combiner is a kernel component of high power fiber laser (HPFL). We demonstrate two types of tapered fiber bundle (TFB) end-pumping combiner able to combining multi-kilowatts of pumping laser. After the experimental test of coupling performance, the 3xl coupler is proved to have a power handling capacity of 2.11 kW with a coupling efficiency of 95.1%, and the 7× 1 coupler is capable of handling pumping power of 4.72 kW with a coupling efficiency of 99.4%. These two coupler have obtained the ability to be used in laser diodes (LDs) direct beam combining and the pumping coupling of multikilowatts level fiber lasers.
基金partially supported by the Shanghai Yangfan Program (No.14YF1401600)the State Key Lab Project of Shanghai Jiao Tong University (No.GKZD030033)+3 种基金the NSFC (Nos.61178007 and 51302285)the External Cooperation Program of BIC,CAS (No.181231KYSB20130007)the National 10000-Talent Programthe CAS 100-Talent Program for financial support
文摘Deposition of two-dimensional(2D) MoS2 materials on the tapered fiber allows various photonic applications including saturable absorbers and four-wave mixing.Ethanol catalytic deposition(ECD) of MoS2 on the optical tapered fiber was proposed and demonstrated in this work.Different from the conventional optical driven deposition using water or organic solvent,the ECD method utilized the high volatility of the ethanol solvent,which significantly increased the movement speed of the MoS2 nanosheets and thus boosted the deposition rate and reduced the minimum power threshold to drive the deposition.We believe the ECD method should be able to be applied to other similar 2D materials such as other types of transition metal chalcogenides.
基金The authors would like to thank Laser Centre,Ibnu-Sina Institute for Scientific and Industrial Research(ISI-SIR),Universiti Teknologi Malaysia(UTM)for the supportThis research work has been supported by UTM_TDR 06G13 research grant+1 种基金Aneez SYUHADA and Muhammad Salleh SHAMSUDIN acknowledge the funding from the UTM Zamalah Scholarship Award supported by the School of Graduate Studies,UTMThe authors want to thank the critics of the anonymous reviewers and valuable suggestions for improving this manuscript.
文摘A sensitive tapered optical fiber sensor incorporating graphene oxide(GO)and polyvinyl alcohol(PVA)composite film for the rapid measurement of changes in relative humidity was proposed and experimentally demonstrated.The sensing principle was based on the intensity modulation of the transmitted light induced by the refractive index changes of the sensitive coatings.The sensing region was obtained by tapering a section of single-mode optical fiber(SMF)from its original 125µm diameter down to 9.03µm.The tapered structure was then modified through deposition of GO/PVA nanocomposites by using the dip-coating technique.The field emission scanning electron microscope(FESEM)and Raman spectroscopy were used to characterize the structure of the composite film.As evidenced by a Fourier transform infrared spectroscopy(FTIR)analysis,the presence of oxygen functional groups(such as−OH and COOH)on the GO structure enabled the attachment of PVA molecules through hydrogen bonding and strong adhesion between GO/PVA layers.The performance of the sensor was tested over a wide range(20%RH to 99.9%RH)of relative humidity.The sensor showed a good response with its signal increasing linearly with the surrounding humidity.The tapered optical fiber sensor with the coating of GO/0.3g PVA achieved the highest sensitivity[0.5290RH(%)].The stability,repeatability,reversibility,as well as response time of the designated sensor were also measured and analyzed.
基金Project supported by the Shanghai Leading Academic Discipline Project (Grant No.S30108)the Universities Foster Innovation Foundation Projects for Major Projects in Ministry of Education (Grant No.708041)
文摘A temperature sensor is demonstrated and fabricated by coating the single-mode tapered optical fiber with temperature-sensitive silicone rubber. It works on the change of the evanescent fields in the tapered optical fiber. Small changes in the refractive index of coating film greatly influence the power of evanescent fields, which modulate the transmission optical power in the waist region. The range of temperature measured is from -20℃ to 70 ℃. The results show that the temperature sensor has high temperature sensitivity (0.012 mW/℃) and good repeatability.
基金supported by the National Basic Research Program of China(973 Program)(Grant No.2012CB821304)the National Natural Science Foundation of China(Grant No.61378040)
文摘We demonstrate a stable Yb:fiber frequency comb with supercontinuum generation by using a specially designed tapered single-mode fiber, in which a spectrum spanning from 500 nm to 1500 nm is produced. The carrier-envelope offset signal of the Yb:fiber comb is measured with a signal-to-noise ratio of more than 40 dB and a linewidth narrower than 120 kHz. The repetition rate and carrier-envelope offset signals are simultaneously phase locked to a microwave reference frequency.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.61027015, 60677031, 60937003)the Shanghai Leading Academic Discipline Project (Grant No.30108)the Science and Technology Commission of Shanghai Municipality (Grant No.10DZ2210900)
文摘In this paper, a novel surface-enhanced Raman scattering (SERS) sensor combined with fused biconical taper fiber (FBTF) and film coated with silver sols is proposed. This structure is designed to significantly increase the SERS active surface when the length of the taper is increased and the radius is reduced, since the penetration depth is inversely proportional to the taper radius and proportional to the taper length according to the fiber-optic evanescent-wave theory. Based on the SERS sensing principle, the feasibility of FBTF sensor is analyzed in this paper. As a result, the Raman spectrum of R6G is obtained from the fused biconical taper zone surface coating with the silver sols in our experiments. The detected concentration is up to 10-7mol/L.
基金the National Key R&D Program of China(No.2020YFB1805802)National Natural Science Foundation of China(Nos.62005012 and 61827817)+1 种基金State Key Laboratory of Rail Traffic Control and Safety(No.RCS2019ZZ007)Beijing Jiaotong University,and Shandong Province Higher Educational Science and Technology Program(No.J18KA368).
文摘A kind of tapered segmented cladding fiber(T-SCF)with large mode area(LMA)is proposed,and the mode and amplification characteristics of T-SCFs with concave,linear,and convex tapered structures are investigated based on finite-element method(FEM)and few-mode steady-state rate equation.Simulation results indicate that the concave tapered structure can introduce high loss for high-order modes(HOMs)that is advantageous to achieve single-mode operation,whereas the convex tapered structure provides large effective mode area that can help to mitigate nonlinear effects.Meanwhile,the small-to-large amplification scheme shows further advantages on stripping off HOMs,and the large-to-small amplification scheme decreases the heat load density induced by the high-power pump.Moreover,singlemode propagation performance,effective mode area,and heat load density of the T-SCF are superior to those of tapered step index fiber(T-SIF).These theoretical model and numerical results can provide instructive suggestions for designing high-power fiber lasers and amplifiers.
基金supported by Fundação de AmparoàPesquisa do Estado de São Paulo(FAPESP)(Grant No.2017/06411-3).
文摘We present a new procedure for protecting micro-optical fibers(tapered fibers)by using the 3-dimensional(3D)printing technology.A standard single-mode optical fiber was tapered down to the diameter of 1mm and embedded in a polymeric matrix obtained by an additive manufacturing routine.We show that the proposed structure protects the fiber taper against environmental humidity while keeping permeability to gas flow and the possibility of the realization of gas detection experiments.To our knowledge,this is the first time 3D printed casings were applied to protect fiber tapers from humidity deterioration.We envisage this new approach will allow the development of new fiber taper devices to better resist in humid environments.
基金This work was supported by the National Key Research&Development Program of China(Grant No.2016YFB0402105)the Belt and Road Special Project approved by Shandong Province for the Introduction of Foreign Experts in 2018,Double-Hundred Talent Plan of Shandong Province,Liaocheng University,China(Grant Nos.31805180301 and 31805180326)Science and Engineering Research Board(SERB),India(Grant No.TAR/2018/000051).
文摘The ascorbic acid(AA)is a biomarker that can be used to detect the symptoms of severe disorders such as scurvy,Parkinson’s,Alzheimer’s,and cardiovascular diseases.In this work,a simple and effective sensor model is developed to diagnose the presence of AA samples.To develop the sensor,a tapered single-mode optical fiber has been used with the well-known phenomenon of localized surface plasmon resonance(LSPR).For LSPR,the tapered region is immobilized with synthesized gold nanoparticles(AuNPs)and zinc oxide nanoparticles(ZnO-NPs)whose absorbance peak wavelengths appear at 519nm and 370nm,respectively.On the basis of nanoparticles(NPs)configurations,two different biosensor probes are developed.In the first one,the sensing region is immobilized with AuNPs and named Probe I.In the second probe,the immobilized layer of AuNPs is further coated with a layer of ZnO-NPs,and a resultant probe is termed as Probe II.The characterizations of synthesized AuNPs and developed fiber probes are done by the ultraviolet-visible(UV-vis)spectrophotometer,high-resolution transmission electron microscope(HR-TEM),atomic force microscopy(AFM),and scanning electron microscope(SEM).To enhance the selectivity,a sensing region of probes is functionalized with ascorbate oxidase enzyme that oxidizes the AA in the presence of oxygen.The response of developed sensor probes is authenticated by sensing the samples of AA in the range from 500 nM to 1 mM,which covers the range of AA found in human bodies,i.e.,40μM-120μM.The performance analysis of the developed sensor probes has been done in terms of their stability,reproducibility,reusability,and selectivity.To observe the stability of AA,a pH-test has also been done that results in a better solubility of AA molecules in phosphate-buffered saline(PBS)solution.
基金The research has been funded by the Indonesian Government,KEMENRISTEKDIKTI(Ministry of Research,Technology,and Higher Education of the Republic of Indonesia)for supporting this work under project scheme University’s Fundamental Research Program(Grant No.918/PKS/ITS/2021).
文摘A rapid and high-performance sensor for lard adulterant in edible oil was developed using the tapered plastic optical fiber(POF)coated with graphene and multi-walled carbon nanotubes.The coating material was deposited onto a tapered POF with a taper waist diameter and a taper length of 0.45 mm and 1 cm,respectively.The addition of the coating material was used to increase the sensitivity and selectivity coefficient of the tapered POF toward the lard substance.The sensing mechanism is based on a simultaneous interaction of lard substance and an evanescent wave of tapered POF with the coating layers.The results showed that graphene coating on the tapered POF increased the selectivity coefficient of the tapered POF towards lard substance from 33.54 to 324.19,and it gave a sensitivity of 0.427 dBm/%.In comparison,multi-walled carbon nanotubes coating increased the selectivity coefficient to 71.65 and increased its sensitivity to 1.189 dBm/%.Thus,the proposed configuration of the tapered POF with the coating material offered a simple configuration for a rapid,high sensitivity and selectivity detection of lard adulterant in edible oils.
基金The authors are grateful for financial support from the National Natural Science Foundation of China (Nos. 61205174, 61401258, 11504209, and 11404195), Excellent Young Scholars Research Fund of Shandong Normal University, and Shandong Province Natural Science Foundation (No. ZR2013EMM009).
文摘An evanescent wave absorption (EWA) sensor based tapered plastic optical fiber (TPOF) coated with monolayer graphene film for ethanol molecules detection is demonstrated in this study. The continuous and monolayer graphene films were grown on a Cu foil by using chemical vapor deposition (CVD) technology. Polymethyl methacrylate (PMMA) was used as the carrier to support the transfer of graphene from Cu foil to the skinless tapered optical fiber core. The accuracy of the TPOF sensor with graphene (G-TPOF sensor) is much higher than that without gra- phene (TPOF sensor), which can be attributed to the molecules enriched on the surface of graphene. The absorbance (A) and the concentrations of ethanol solution show an excellent proportional relationship in a range of 0--100%. The dynamic response of the G-TPOF sensor has shown strong reversibility, repeatability and stability at room temperature. The response time and recovery time of the G-TPOF sensor for different concentrations are all less than 30 s. Beyond that, we selected the Chinese liquor as the analyte, and the results are consistent with the concen- tration-list obtained in the experiment.
基金supported by the National Natural Science Foundation of China (No.61377075)the Training Program for Leading Talents of Universities in Tianjin。
文摘A simple structure optical fiber sensor for relative humidity(RH) and temperature measurement is proposed and verified in this paper, which is based on graphene oxide quantum dots and polyvinyl alcohol(GOQDs-PVA) composite coated tapered no-core fiber(NCF) combined with a fiber Bragg grating(FBG). FBG is insensitive to humidity and sensitive to temperature, which is used to compensate temperature of the sensor. Experimental results show this sensor has humidity sensitivity of 143.27 pm/%RH ranging from 30%RH to 80%RH and the temperature sensitivity of 9.21 pm/℃. The proposed sensor has advantages of simple structure, good repeatability, and good stability, which is expected to be used in both RH and temperature measurement in biological and chemical fields.
文摘Core mode cutoff is a useful concept not only for a tapered single-core fiber(SCF) but also for a tapered multicore fiber(MCF) to realize cladding mode transmission. In this paper, cut-off conditions of either core mode for tapered SCFs or supermodes for MCFs are theoretically investigated. Rigorous analytical formulas are derived for the modes of SCF by a three-layer waveguide model, and an approximation formula of the cut-off condition is given for the LP01 mode. The supermodes of MCFs are analyzed by the coupling mode theory, and the cut-off condition is calculated by a numerical method. Simulation results show that the in-phase supermode of MCFs has a similar cut-off condition with that of SCF. Based on this property, a convenient approximate formula is given to estimate the cut-off condition of the in-phase supermode for tapered MCFs.
基金This work was supported by the National Natural Science Foundation of China under project No.60907036 and No.61036012the Natural Science Foundation of Zhejiang Province,China under project No.Y1090021+1 种基金the Fundamental Research Funds for the Central Universities under project No.2010QNA5038the Specialized Research Fund for the Doctoral Program of Higher Education of China under project No.J20091636.
文摘As a low-dimensional optical fiber with diameter close to or below the wavelength of light,optical micro/nanofiber(MNF)offers a number of favorable properties for optical sensing,which have been exploited in a variety of sensing applications,including physical,chemical,and biological sensors.In this paper we review the principles and applications of silica,glass,and polymer optical micro/nanofibers for physical and chemical sensing.
基金carried out in School of Physics and Astronomy in University of Southampton, UK and founded by both of IIE/SRF and CARA
文摘The thin, long length and high smoothness silica photonic nanowires and taper optical fiber were fabricated using a simple and low cost chemical etching method. A two-steps wet etch process were used consisting of etching with 30% HF acid to remove cladding and 24% HF acid to decrease fiber core diameter. An approach for on-line monitoring of etching using 1300 nm light power transmitted in the optical fiber was used to determine the diameter of the remaining core and showed a transition between two different operation regimes of nanofiber from the embedded regime, where the mode was isolated from the environment, to the evanescent regime. The data indicated that the diameter of the silica fiber decreased linearly for both 30% and 24% HF acid with 1.2 and 0.1/zm/min grad diameter, respectively at room temperature, and more than 70% of the mode intensity could propagate outside fiber when the core diameter was less than 1μm. The results of fiber taper showed that the fiber was tapered by a factor of 20 while retaining a thin core structure and leaving about more than 85% of core structure.
基金supported by the National Natural Science Foundation of China(Nos.61377081 and 61007035)the Chen Guang project by Shanghai Municipal Education Commission and Shanghai Education Development Foundation(No.12CG48)the Science and Technology Commission of Shanghai Municipality(STCSM)(No.14511105602)
文摘This Letter presents intrinsic Fabry–Perot interferometers in the fiber tapers fabricated by the femtosecond laser micromachining technique. The sensing of temperatures as high as 1000°C based on the fiber device is characterized, with a sensitivity of 15.28 pm∕°C. A nearly linear refractive index sensing is also obtained by using the fringe visibility to characterize, with a sensitivity of 73.05 dB∕RIU. These intrinsic Fabry–Perot interferometers in fiber tapers may be useful in applications of high-temperature and linear refractive index sensing.
基金supported in part by the National "973" Program of China(No.2011CB301700)the National Natural Science Foundation of China(Nos.61007052, 61071011,61107041,61127016)+3 种基金the International Cooperation Project from the Ministry of Science and Technology of China(No.2011FDA11780)the STCSM Project(Nos.09JC1408100,10DJ1400402)the "SMC Young Star" Scientist Program of Shanghai Jiao Tong Universitythe National Key Lab Projects(No. GKZD030021)
文摘A modal interferometer is experimentally demonstrated based on tapering a single-mode-multimode-single- mode (SMS) fiber structure heated by hydrogen flame. The interference fringe begins to form when tapering length is 19.8 mm, and becomes regular and clear when the tapering length is longer and the tapered waist diameter is smaller. Annealing process is undertaken to achieve a high extension ratio of approximately 17 dB with free spectral range of 1.5 nm when the tapering length is 33 mm and the tapered waist diameter is approximately 5 μm. The temperature and axial strain dependences of the tapered SMS structure are characterized, and the measured temperature and strain coefficients are +7 pm/℃ and -9.536 pm/με, respectively.