Surface plasmon resonance induced tunable polarization filters based on nanoscale gold film-coated photonic crystal fibers were proposed and analyzed. The characteristics of the polarization filter were calculated by ...Surface plasmon resonance induced tunable polarization filters based on nanoscale gold film-coated photonic crystal fibers were proposed and analyzed. The characteristics of the polarization filter were calculated by finite element method (FEM). The gold film was selectively coated on the inner wall of one cladding air hole which was located near the fiber core along the y-axis direction. When the phase of core fundamental mode and surface plasmon polaritons (SPPs) mode matches, the two modes couple with each other intensely. Numerical results show that the resonance wavelength and strength vary with fiber structural parameters and the index of the infilling liquid. The fiber parameters were optimized to achieve specific functions. Under the optimal structure, we realized a dual channel filter at the communication wavelength of 1.31 μm and 1.55 μm fory polarization direction and x polarization direction. Then a single channel polarized filter at the communication wavelength of 1.55 μm is also achieved by adjusting the refractive index of the infilling liquid. The proposed polarization filters realized dual channel filtering and single channel filtering simultaneously under the same structure for the first time to the best of our knowledge.展开更多
The supercontinuum (SC) generation in all-normal dispersion (ANDi) photonic-crystal fiber (PCF) pumped by high power picosecond pulses are investigated in this paper. Our results show that an octave SC may be ac...The supercontinuum (SC) generation in all-normal dispersion (ANDi) photonic-crystal fiber (PCF) pumped by high power picosecond pulses are investigated in this paper. Our results show that an octave SC may be achieved by pumping the ANDi PCF with picosecond pump pulses. However, the PCF length required may have to be lengthened to several tens of centimeters, which is much longer than that with femtosecond pump pulses. The relatively long PCF gives rise to much higher Raman gain and stronger Raman frequency shift compared to those with femtosecond pump pulses, which in turn not only cause a distorted temporal waveform and an un-flattened spectrum, but also severely degrade the coherence of the generated SC.展开更多
This paper reports fiber Bragg gratings (FBGs) inscribed in a small-core Ge-doped photonic crystal fibers with a UV laser and a Talbot interferometer. The responses of such FBGs to temper- ature, strain, bending, an...This paper reports fiber Bragg gratings (FBGs) inscribed in a small-core Ge-doped photonic crystal fibers with a UV laser and a Talbot interferometer. The responses of such FBGs to temper- ature, strain, bending, and transverse-loading were systematically investigated. The Bragg wavelength of the FBGs shifts toward longer wavelengths with increasing temperature, tensile strain, and transverse-loading. The bending and transverse- loading properties of the FBGs are sensitive to the fiber orientations.展开更多
A simplified structure of birefringent chalcogenide As 2 Se 3 photonic crystal fiber(PCF) is designed.Properties of birefringence,polarization extinction ratio,chromatic dispersion,nonlinear coefficient,and transmis...A simplified structure of birefringent chalcogenide As 2 Se 3 photonic crystal fiber(PCF) is designed.Properties of birefringence,polarization extinction ratio,chromatic dispersion,nonlinear coefficient,and transmission are studied by using the multipole method,the finite-difference beam propagation method,and the adaptive split-step Fourier method.Considering that the zero dispersion wavelength of our proposed fiber is about 4 μm,we have analysed the mechanism of spectral broadening in PCFs with different pitches in detail,with femtosecond pulses at a wavelength of 4 μm as the pump pulses.Especially,mid-infrared broadband polarized supercontinuums are obtained in a 3-cm PCF with an optimal pitch of 2 μm.Their spectral width at 20 dB reaches up to 12 μm.In the birefringent PCF,we find that the supercontinuum generation changes with the pump alignment angle.Research results show that no coupling between eigenpolarization modes are observed at the maximum average power(i.e.,37 mW),which indicates that the polarization state is well maintained.展开更多
Picosecond pulse pumped supercontinuum generation in photonic crystal fiber is investigated by performing a series of comparative experiments. The main purpose is to investigate the supercontinuum generation processes...Picosecond pulse pumped supercontinuum generation in photonic crystal fiber is investigated by performing a series of comparative experiments. The main purpose is to investigate the supercontinuum generation processes excited by a given pump source through the experimental study of some specific fibers. A 20-W all-fiber picosecond master oscillator-power amplifier (MOPA) laser is used to pump three different kinds of photonic crystal fibers for supercontinuum generation. Three diverse supercontinuum formation processes are observed to correspond to photonie crystal fibers with distinct dis- persion properties. The experimental results are consistent with the relevant theoretical results. Based on the above analyses, a watt-level broadband white light supercontinuum source spanning from 500 nm to beyond 1700 nm is demonstrated by using a picosecond fiber laser in combination with the matched photonic crystal fiber. The limitation of the group velocity matching curve of the photonic crystal fiber is also discussed in the paper.展开更多
The theoretical study of dielectric-chiral photonic crystal fiber (PCF) with an elliptical hollow core is presented. The band structure of chiral photonic crystal (PhC) is calculated by using a modified plane-wave...The theoretical study of dielectric-chiral photonic crystal fiber (PCF) with an elliptical hollow core is presented. The band structure of chiral photonic crystal (PhC) is calculated by using a modified plane-wave expansion (PWE) method. By examining the out-of-plane photonic bandgaps (PBGs) of chiral PhC, a kind of chiral PCF with a hollow core is designed and their eigenstates are calculated. The distributions of mode field and polarization state are demonstrated, and how the structural asymmetry of the core together with the chirality in the background affects the modal polarization is discussed. The dependences of birefringence on chirality for different ellipticities of core are investigated.展开更多
We present a numerical and experimental study of the propagation characteristics of photonic crystal fibers(PCFs)selectively filled with ionic liquid(IL;1-butyl-3-methylimidazolium iodine).Three types of IL-filled PCF...We present a numerical and experimental study of the propagation characteristics of photonic crystal fibers(PCFs)selectively filled with ionic liquid(IL;1-butyl-3-methylimidazolium iodine).Three types of IL-filled PCF are investigated:one with all air holes filled,one with an IL-filled air hole in the second ring,and one with an IL-filled air hole in the third ring.The results show that the third type of IL-filled PCF is the most sensitive to temperature;the sensitivity of resonant dips between the LP01 and LP21 modes is−2.9 nm/XC.Moreover,the intensity of the resonant dips changes with the polarization angle of the light source;the sensitivity is−0.79 dB per unit polarization angle.Based on this property,IL-filled PCFs with different utilities can be realized by changing the filling position flexibly.Consequently,IL-filled PCFs can be used under flexible conditions and controllable temperatures to create a compact polarization-angle sensor.展开更多
We report supercontinuum (SC) generation in a lead silicate SF57 photonic crystal fiber by using a 1550 nm pump source. The effective nonlinear coefficient of the SF57 fiber is simulated to be 111.5 W-1 .km- 1 at 15...We report supercontinuum (SC) generation in a lead silicate SF57 photonic crystal fiber by using a 1550 nm pump source. The effective nonlinear coefficient of the SF57 fiber is simulated to be 111.5 W-1 .km- 1 at 1550 nm. The fiber also shows ultraflat dispersion from 1700 nm to 2100 nm. Our results reveal that with an increase of the average power of the incident pulse from 10 mW to 90 mW, the SC of the SF57 photonic crystal fiber is generated from 1300 nm to 1900 nm with high stability and without significant change in spectral broadening.展开更多
We investigate numerically and experimentally the modification of the spontaneous emission rate for micrometersized light sources embedded in a hollow-core photonic crystal fiber (HCPCF). The diameter of the light s...We investigate numerically and experimentally the modification of the spontaneous emission rate for micrometersized light sources embedded in a hollow-core photonic crystal fiber (HCPCF). The diameter of the light source is deliberately chosen such that they could be easily introduced into the central hole of the hollow-core photonic crystal fiber by capillary force. The photoluminescence from the microparticles is measured by using an inverted microscope in combination with a spectrometer. The modification of the spontaneous emission rate is observed in a wavelength region where there is no band gap. The experimental observations are consistent with the simulation results obtained by the plane wave expansion and finite-difference time-domain techniques.展开更多
Understanding bend loss in single-ring hollow-core photonic crystal fibers(PCFs)is becoming of increasing importance as the fibers enter practical applications.While purely numerical approaches are useful,there is a n...Understanding bend loss in single-ring hollow-core photonic crystal fibers(PCFs)is becoming of increasing importance as the fibers enter practical applications.While purely numerical approaches are useful,there is a need for a simpler analytical formalism that provides physical insight and can be directly used in the design of PCFs with low bend loss.We show theoretically and experimentally that a wavelength-dependent critical bend radius exists below which the bend loss reaches a maximum,and that this can be calculated from the structural parameters of a fiber using a simple analytical formula.This allows straightforward design of single-ring PCFs that are bend-insensitive for specified ranges of bend radius and wavelength.It also can be used to derive an expression for the bend radius that yields optimal higher-order mode suppression for a given fiber structure.展开更多
Optical fibers have been widely applied to telecommunication,imaging,lasers,and sensing.Among the different types of fibers,photonic crystal fibers(PCFs),also called microstructured optical fibers,characterized by air...Optical fibers have been widely applied to telecommunication,imaging,lasers,and sensing.Among the different types of fibers,photonic crystal fibers(PCFs),also called microstructured optical fibers,characterized by air holes arranged along the length of fibers have experienced tremendous advance due to their unique advantages.They are regarded as a desirable platform to excite surface plasmon resonance(SPR)because of easy realization of phase matching conditions between the fundamental core mode and the plasmonic mode,which plays a critical role in miniaturization and integration of SPR sensors.In this mini-review,the current status of PCF sensors based on SPR is summarized.The theory of SPR is discussed,and simulation methods for PCF-SPR sensors are described.The important parameters including the refractive index detection range,resonance wavelength,and spectral sensitivity responsible for the sensing properties of PCF-SPR sensors are reviewed.The fabrication and the comparison of performances are also illustrated,and,finally,the challenges and future perspectives are outlined.展开更多
Photonic crystal fibers are attractive since we can realize a wide variety of unique features in the PCFs, which cannot be realized in conventional single-mode fibers. We describe recent progress in the PCF.
By offering greatly enhanced control of light compared to conventional step-index structures, photonic crystal fibres are radically improving the performance of linear and nonlinear fibre devices, including gas-Raman ...By offering greatly enhanced control of light compared to conventional step-index structures, photonic crystal fibres are radically improving the performance of linear and nonlinear fibre devices, including gas-Raman cells, super-continuum generators, soliton systems and cladding-pumped lasers.展开更多
An overview of the progress on pulse-preserving, coherent, nonlinear fiber-based supercontinuum generation is presented. The context encompasses various wavelength ranges and pump sources, starting with silica photoni...An overview of the progress on pulse-preserving, coherent, nonlinear fiber-based supercontinuum generation is presented. The context encompasses various wavelength ranges and pump sources, starting with silica photonic crystal fibers pumped with 1.0 μm femtosecond lasers up to chalcogenide step-index and microstructured fibers pumped from optical parametric amplifiers tuned to mid-infrared wavelengths. In particular, silica and silicatebased all-normal dispersion(ANDi) photonic crystal fibers have been demonstrated for pumping with femtosecond lasers operating at 1.56 μm with the recorded spectra covering 0.9–2.3 μm. This matches amplification bands of robust fiber amplifiers and femtosecond lasers. The review therefore focuses specifically on this wavelength range, discussing glass and nonlinear fiber designs, experimental results on supercontinuum generation up to the fundamental limit of oxide glass fiber transmission around 2.8 μm, and various limitations of supercontinuum bandwidth and coherence. Specifically, the role of nonlinear response against the role of dispersion profile shape is analyzed for two different soft glass ANDi fibers pumped at more than 2.0 μm. A spatio-temporal interaction of the fundamental fiber mode with modes propagating in the photonic lattice of the discussed ANDi fibers is shown to have positive effects on the coherence of the supercontinuum at pump pulse durations of 400 fs. Finally, the design and development of graded-index, nanostructured core optical fibers are discussed.In such structures the arbitrary shaping of the core refractive index profile could significantly improve the engineering flexibility of dispersion and effective mode area characteristics, and would be an interesting platform to further study the intermodal interaction mechanisms and their impact on supercontinuum coherence for subpicosecond laser pumped setups.展开更多
A photonic crystal fiber has been filled with a cholesteric liquid crystal. A temperature sensitive photonic band gap effect was observed, which was especially pronounced around the liquid crystal phase transition tem...A photonic crystal fiber has been filled with a cholesteric liquid crystal. A temperature sensitive photonic band gap effect was observed, which was especially pronounced around the liquid crystal phase transition temperature.展开更多
We demonstrate a highly birefringent photonic crystal fiber by utilizing the asymmetric core design. Based on spectral measurements of the polarization mode interfering, we estimate that the fiber has a beat length of...We demonstrate a highly birefringent photonic crystal fiber by utilizing the asymmetric core design. Based on spectral measurements of the polarization mode interfering, we estimate that the fiber has a beat length of about 0.33 mm at 1545 nm.展开更多
We measured macro-bending losses for two large mode area photonic crystal fibers. Experimental results show that macro-bending loss and loss window are dependent on the parameter d/∧ and number of air-holes ring in t...We measured macro-bending losses for two large mode area photonic crystal fibers. Experimental results show that macro-bending loss and loss window are dependent on the parameter d/∧ and number of air-holes ring in the cladding.展开更多
An equal channel spacing Sagnac filter is proposed using a high-birefringent photonic crystal fiber (PCF) with birefringence square to the operation wavelength. A PCF with four smaller central air holes sur-rounded ...An equal channel spacing Sagnac filter is proposed using a high-birefringent photonic crystal fiber (PCF) with birefringence square to the operation wavelength. A PCF with four smaller central air holes sur-rounded by larger air holes is applied in a Sagnac filter with optimized parameters to achieve equal channel spacing of 0.8 nm. Given that the birefringence of this PCF is square to the operation wavelength, the channel spacing of the proposed filter changes by only 0.03 nm within a wavelength range from 1400 to 1650 nm; this is about one order of magnitude less than that constructed with conventional high-birefringent fibers.展开更多
A novel fabrication method of multi-core photonic crystal fibers is proposed on the basis of a fiber-embedded technique. A taper tower is used to modify the structures of the fiber preform, and four steps of fiber fab...A novel fabrication method of multi-core photonic crystal fibers is proposed on the basis of a fiber-embedded technique. A taper tower is used to modify the structures of the fiber preform, and four steps of fiber fabrication and different structures of fiber samples are given. The mode structures and beating characteristics of a photonic crystal fiber sample with two successive cores are investigated in detail with the help of a supercontinuum light source, a charge-coupled device (CCD) camera, and an optical spectrum analyzer. The test results show a clear beating phenomenon between two orthotropic polarization modes with a 2.8-nm peak interval in wavelength.展开更多
With the incorporation of noble metal materials,photonic crystal fibers(PCFs)could be performed as an effective platform for refractive index sensing of the filling analytes.Furthermore,by coating functional dielectri...With the incorporation of noble metal materials,photonic crystal fibers(PCFs)could be performed as an effective platform for refractive index sensing of the filling analytes.Furthermore,by coating functional dielectric layers upon the metal surfaces,the resonance energy transfer is modulated from the core mode of the PCFs towards the surface plasmon resonance mode of the metals,and the sensing performance could be boosted.Here,considering that the exciton-plasmon coupling is efficient between perovskite quantum dots(QDs)and gold,a kind of CsPbBr_(3) QDs/Au bilayer coated triangular-lattice PCFs has been simulated numerically as the refractive index sensors.With the optimization of the QDs and gold layer thicknesses,together with the variation of the central hole size of the PCFs,in the refractive index(RI)region of 1.26 to 1.34,a rather narrow full width at half maximum(FWHM)of the loss spectra was achieved as 13.74 nm when the central hole size was 1.28μm and the highest figure of merit was 63.79 RIU(the central hole size was 1.53μm).This work demonstrates that the analyte identification accuracy was enhanced by FWHM narrowing of the loss spectra;in addition,taking the abundance of the material choice of perovskite QDs into consideration,more analytes could be detected effectively.Moreover,by adopting asymmetric structures,the sensitivity of the PCFs based refractive index sensors could be further improved.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.61505175 and 61475134)the Natural Science Foundation of Hebei Province,China(Grant Nos.F2017203110 and F2017203193)
文摘Surface plasmon resonance induced tunable polarization filters based on nanoscale gold film-coated photonic crystal fibers were proposed and analyzed. The characteristics of the polarization filter were calculated by finite element method (FEM). The gold film was selectively coated on the inner wall of one cladding air hole which was located near the fiber core along the y-axis direction. When the phase of core fundamental mode and surface plasmon polaritons (SPPs) mode matches, the two modes couple with each other intensely. Numerical results show that the resonance wavelength and strength vary with fiber structural parameters and the index of the infilling liquid. The fiber parameters were optimized to achieve specific functions. Under the optimal structure, we realized a dual channel filter at the communication wavelength of 1.31 μm and 1.55 μm fory polarization direction and x polarization direction. Then a single channel polarized filter at the communication wavelength of 1.55 μm is also achieved by adjusting the refractive index of the infilling liquid. The proposed polarization filters realized dual channel filtering and single channel filtering simultaneously under the same structure for the first time to the best of our knowledge.
基金the National High Technology Research and Development Program of China(Grant No.2011AA030203)the National Natural Science Foundation of China(Grant No.61250017)the Key Research Program of the Chinese Academy Sciences(Grant No.KJZD-EW-W02)
文摘The supercontinuum (SC) generation in all-normal dispersion (ANDi) photonic-crystal fiber (PCF) pumped by high power picosecond pulses are investigated in this paper. Our results show that an octave SC may be achieved by pumping the ANDi PCF with picosecond pump pulses. However, the PCF length required may have to be lengthened to several tens of centimeters, which is much longer than that with femtosecond pump pulses. The relatively long PCF gives rise to much higher Raman gain and stronger Raman frequency shift compared to those with femtosecond pump pulses, which in turn not only cause a distorted temporal waveform and an un-flattened spectrum, but also severely degrade the coherence of the generated SC.
基金supported by the Alexander von Humboldt Foundation, the National Science Foundation of China under Grant No. 60507013, and the Thuringian Ministry of Education and Cultural Affairs.
文摘This paper reports fiber Bragg gratings (FBGs) inscribed in a small-core Ge-doped photonic crystal fibers with a UV laser and a Talbot interferometer. The responses of such FBGs to temper- ature, strain, bending, and transverse-loading were systematically investigated. The Bragg wavelength of the FBGs shifts toward longer wavelengths with increasing temperature, tensile strain, and transverse-loading. The bending and transverse- loading properties of the FBGs are sensitive to the fiber orientations.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61178026 and 60978028)the Specialized Research Fund for the Doctoral Program of Higher Education,China(Grant No.20091333110010)the Natural Science Foundation of Hebei Province,China(Grant No.F2009000481)
文摘A simplified structure of birefringent chalcogenide As 2 Se 3 photonic crystal fiber(PCF) is designed.Properties of birefringence,polarization extinction ratio,chromatic dispersion,nonlinear coefficient,and transmission are studied by using the multipole method,the finite-difference beam propagation method,and the adaptive split-step Fourier method.Considering that the zero dispersion wavelength of our proposed fiber is about 4 μm,we have analysed the mechanism of spectral broadening in PCFs with different pitches in detail,with femtosecond pulses at a wavelength of 4 μm as the pump pulses.Especially,mid-infrared broadband polarized supercontinuums are obtained in a 3-cm PCF with an optimal pitch of 2 μm.Their spectral width at 20 dB reaches up to 12 μm.In the birefringent PCF,we find that the supercontinuum generation changes with the pump alignment angle.Research results show that no coupling between eigenpolarization modes are observed at the maximum average power(i.e.,37 mW),which indicates that the polarization state is well maintained.
基金supported by the State Key Program of the National Natural Science Foundation of China(Grant No.61235008)the Postgraduate Innovation Foundation of National University of Defense Technology,China(Grant No.B110704)
文摘Picosecond pulse pumped supercontinuum generation in photonic crystal fiber is investigated by performing a series of comparative experiments. The main purpose is to investigate the supercontinuum generation processes excited by a given pump source through the experimental study of some specific fibers. A 20-W all-fiber picosecond master oscillator-power amplifier (MOPA) laser is used to pump three different kinds of photonic crystal fibers for supercontinuum generation. Three diverse supercontinuum formation processes are observed to correspond to photonie crystal fibers with distinct dis- persion properties. The experimental results are consistent with the relevant theoretical results. Based on the above analyses, a watt-level broadband white light supercontinuum source spanning from 500 nm to beyond 1700 nm is demonstrated by using a picosecond fiber laser in combination with the matched photonic crystal fiber. The limitation of the group velocity matching curve of the photonic crystal fiber is also discussed in the paper.
基金Project supported by the National Natural Science Foundation of China(Grant No.60977032)
文摘The theoretical study of dielectric-chiral photonic crystal fiber (PCF) with an elliptical hollow core is presented. The band structure of chiral photonic crystal (PhC) is calculated by using a modified plane-wave expansion (PWE) method. By examining the out-of-plane photonic bandgaps (PBGs) of chiral PhC, a kind of chiral PCF with a hollow core is designed and their eigenstates are calculated. The distributions of mode field and polarization state are demonstrated, and how the structural asymmetry of the core together with the chirality in the background affects the modal polarization is discussed. The dependences of birefringence on chirality for different ellipticities of core are investigated.
基金supported partly by the National Natural Science Foundation of China(Grant Nos.11804171,11674177,and 61775107)partly by the Natural Science Foundation of Tianjin,China(Grant No.16JCZDJC31000)partly by the Self-made Experiment Teaching Instrument Project of Nankai University 2018(Grant No.2018NKZZYQ04).
文摘We present a numerical and experimental study of the propagation characteristics of photonic crystal fibers(PCFs)selectively filled with ionic liquid(IL;1-butyl-3-methylimidazolium iodine).Three types of IL-filled PCF are investigated:one with all air holes filled,one with an IL-filled air hole in the second ring,and one with an IL-filled air hole in the third ring.The results show that the third type of IL-filled PCF is the most sensitive to temperature;the sensitivity of resonant dips between the LP01 and LP21 modes is−2.9 nm/XC.Moreover,the intensity of the resonant dips changes with the polarization angle of the light source;the sensitivity is−0.79 dB per unit polarization angle.Based on this property,IL-filled PCFs with different utilities can be realized by changing the filling position flexibly.Consequently,IL-filled PCFs can be used under flexible conditions and controllable temperatures to create a compact polarization-angle sensor.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61178026 and 60978028)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20091333110010)+1 种基金the Natural Science Foundation of Hebei Province, China (Grant No. E2012203035)the NCRIS, Australia
文摘We report supercontinuum (SC) generation in a lead silicate SF57 photonic crystal fiber by using a 1550 nm pump source. The effective nonlinear coefficient of the SF57 fiber is simulated to be 111.5 W-1 .km- 1 at 1550 nm. The fiber also shows ultraflat dispersion from 1700 nm to 2100 nm. Our results reveal that with an increase of the average power of the incident pulse from 10 mW to 90 mW, the SC of the SF57 photonic crystal fiber is generated from 1300 nm to 1900 nm with high stability and without significant change in spectral broadening.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10674051 and 10811120010)the Program for Innovative Research Team of the Higher Education of Guangdong, China (Grant No 06CXTD005)
文摘We investigate numerically and experimentally the modification of the spontaneous emission rate for micrometersized light sources embedded in a hollow-core photonic crystal fiber (HCPCF). The diameter of the light source is deliberately chosen such that they could be easily introduced into the central hole of the hollow-core photonic crystal fiber by capillary force. The photoluminescence from the microparticles is measured by using an inverted microscope in combination with a spectrometer. The modification of the spontaneous emission rate is observed in a wavelength region where there is no band gap. The experimental observations are consistent with the simulation results obtained by the plane wave expansion and finite-difference time-domain techniques.
文摘Understanding bend loss in single-ring hollow-core photonic crystal fibers(PCFs)is becoming of increasing importance as the fibers enter practical applications.While purely numerical approaches are useful,there is a need for a simpler analytical formalism that provides physical insight and can be directly used in the design of PCFs with low bend loss.We show theoretically and experimentally that a wavelength-dependent critical bend radius exists below which the bend loss reaches a maximum,and that this can be calculated from the structural parameters of a fiber using a simple analytical formula.This allows straightforward design of single-ring PCFs that are bend-insensitive for specified ranges of bend radius and wavelength.It also can be used to derive an expression for the bend radius that yields optimal higher-order mode suppression for a given fiber structure.
基金jointly supported by the National Natural Science Foundation of China(No.51474069)the Local Universities Reformation and Development Personnel Training Supporting Project from Central Authorities(No.140119001)+1 种基金the Heilongjiang Postdoctoral Foundation(No.LBH-Q20081)the City University of Hong Kong Strategic Research Grant(SRG)(Nos.7005105 and 7005265)。
文摘Optical fibers have been widely applied to telecommunication,imaging,lasers,and sensing.Among the different types of fibers,photonic crystal fibers(PCFs),also called microstructured optical fibers,characterized by air holes arranged along the length of fibers have experienced tremendous advance due to their unique advantages.They are regarded as a desirable platform to excite surface plasmon resonance(SPR)because of easy realization of phase matching conditions between the fundamental core mode and the plasmonic mode,which plays a critical role in miniaturization and integration of SPR sensors.In this mini-review,the current status of PCF sensors based on SPR is summarized.The theory of SPR is discussed,and simulation methods for PCF-SPR sensors are described.The important parameters including the refractive index detection range,resonance wavelength,and spectral sensitivity responsible for the sensing properties of PCF-SPR sensors are reviewed.The fabrication and the comparison of performances are also illustrated,and,finally,the challenges and future perspectives are outlined.
文摘Photonic crystal fibers are attractive since we can realize a wide variety of unique features in the PCFs, which cannot be realized in conventional single-mode fibers. We describe recent progress in the PCF.
文摘By offering greatly enhanced control of light compared to conventional step-index structures, photonic crystal fibres are radically improving the performance of linear and nonlinear fibre devices, including gas-Raman cells, super-continuum generators, soliton systems and cladding-pumped lasers.
基金Funding.Fundacja na rzecz Nauki Polskiej(FNP)(First TEAM/2016-1/1)
文摘An overview of the progress on pulse-preserving, coherent, nonlinear fiber-based supercontinuum generation is presented. The context encompasses various wavelength ranges and pump sources, starting with silica photonic crystal fibers pumped with 1.0 μm femtosecond lasers up to chalcogenide step-index and microstructured fibers pumped from optical parametric amplifiers tuned to mid-infrared wavelengths. In particular, silica and silicatebased all-normal dispersion(ANDi) photonic crystal fibers have been demonstrated for pumping with femtosecond lasers operating at 1.56 μm with the recorded spectra covering 0.9–2.3 μm. This matches amplification bands of robust fiber amplifiers and femtosecond lasers. The review therefore focuses specifically on this wavelength range, discussing glass and nonlinear fiber designs, experimental results on supercontinuum generation up to the fundamental limit of oxide glass fiber transmission around 2.8 μm, and various limitations of supercontinuum bandwidth and coherence. Specifically, the role of nonlinear response against the role of dispersion profile shape is analyzed for two different soft glass ANDi fibers pumped at more than 2.0 μm. A spatio-temporal interaction of the fundamental fiber mode with modes propagating in the photonic lattice of the discussed ANDi fibers is shown to have positive effects on the coherence of the supercontinuum at pump pulse durations of 400 fs. Finally, the design and development of graded-index, nanostructured core optical fibers are discussed.In such structures the arbitrary shaping of the core refractive index profile could significantly improve the engineering flexibility of dispersion and effective mode area characteristics, and would be an interesting platform to further study the intermodal interaction mechanisms and their impact on supercontinuum coherence for subpicosecond laser pumped setups.
文摘A photonic crystal fiber has been filled with a cholesteric liquid crystal. A temperature sensitive photonic band gap effect was observed, which was especially pronounced around the liquid crystal phase transition temperature.
文摘We demonstrate a highly birefringent photonic crystal fiber by utilizing the asymmetric core design. Based on spectral measurements of the polarization mode interfering, we estimate that the fiber has a beat length of about 0.33 mm at 1545 nm.
文摘We measured macro-bending losses for two large mode area photonic crystal fibers. Experimental results show that macro-bending loss and loss window are dependent on the parameter d/∧ and number of air-holes ring in the cladding.
基金supported by the Key Project of the Ministry of Education (No. 206006)the Tianjin Key Project of Applied and Basic Research Programs (No.07JCZDJC06000)the Tianjin Project of the Com-mittee of Education (No. 2006BA30)
文摘An equal channel spacing Sagnac filter is proposed using a high-birefringent photonic crystal fiber (PCF) with birefringence square to the operation wavelength. A PCF with four smaller central air holes sur-rounded by larger air holes is applied in a Sagnac filter with optimized parameters to achieve equal channel spacing of 0.8 nm. Given that the birefringence of this PCF is square to the operation wavelength, the channel spacing of the proposed filter changes by only 0.03 nm within a wavelength range from 1400 to 1650 nm; this is about one order of magnitude less than that constructed with conventional high-birefringent fibers.
基金the China Scholarship Council(CSC) and the Research Foundation of Harbin Engineering University
文摘A novel fabrication method of multi-core photonic crystal fibers is proposed on the basis of a fiber-embedded technique. A taper tower is used to modify the structures of the fiber preform, and four steps of fiber fabrication and different structures of fiber samples are given. The mode structures and beating characteristics of a photonic crystal fiber sample with two successive cores are investigated in detail with the help of a supercontinuum light source, a charge-coupled device (CCD) camera, and an optical spectrum analyzer. The test results show a clear beating phenomenon between two orthotropic polarization modes with a 2.8-nm peak interval in wavelength.
基金supported by National Key Research and Development Program of China(Grant No.2016YFA0202401)National Natural Science Foundation of China(Grant No.61705066)+1 种基金Open Fund of IPOC(BUPT)(Grant No.IPOC2018B004)Fundamental Research Funds for the Central Universities,China(Grant No.2020JG002).
文摘With the incorporation of noble metal materials,photonic crystal fibers(PCFs)could be performed as an effective platform for refractive index sensing of the filling analytes.Furthermore,by coating functional dielectric layers upon the metal surfaces,the resonance energy transfer is modulated from the core mode of the PCFs towards the surface plasmon resonance mode of the metals,and the sensing performance could be boosted.Here,considering that the exciton-plasmon coupling is efficient between perovskite quantum dots(QDs)and gold,a kind of CsPbBr_(3) QDs/Au bilayer coated triangular-lattice PCFs has been simulated numerically as the refractive index sensors.With the optimization of the QDs and gold layer thicknesses,together with the variation of the central hole size of the PCFs,in the refractive index(RI)region of 1.26 to 1.34,a rather narrow full width at half maximum(FWHM)of the loss spectra was achieved as 13.74 nm when the central hole size was 1.28μm and the highest figure of merit was 63.79 RIU(the central hole size was 1.53μm).This work demonstrates that the analyte identification accuracy was enhanced by FWHM narrowing of the loss spectra;in addition,taking the abundance of the material choice of perovskite QDs into consideration,more analytes could be detected effectively.Moreover,by adopting asymmetric structures,the sensitivity of the PCFs based refractive index sensors could be further improved.