Exploring new material systems and enhancing the birefringence of compounds is a highly valuable endeavor.In this study,we introduce a novel method to enhance the birefringence of inorganic compounds by inducing struc...Exploring new material systems and enhancing the birefringence of compounds is a highly valuable endeavor.In this study,we introduce a novel method to enhance the birefringence of inorganic compounds by inducing structural alignment through linear groups and fluoride ions.We report on two new compounds:HgGa_(2)(SeO_(3))_(4) and Hg_(2)Ga(Se_(O)_(3))_(2)F.HgGa_(2)(SeO_(3))_(4) crystallizes in a non-centrosymmetric(NCS)space group,exhibiting a second harmonic generation(SHG)efficiency of approximately 60% that of commercial KH2PO4(KDP),with a birefringence of 0.032@546 nm.Hg_(2)Ga(Se_(O)_(3))_(2)F,on the other hand,crystallizes in a centrosymmetric space(CS)group and represents the first reported HgI-based selenite birefringent material.Due to the influence of the linear group Hg_(2)O_(2),its birefringence is significantly enhanced to 0.111@546 nm,which is 3.5 times that of HgGa_(2)(SeO_(3))_(4).Moreover,both compounds demonstrate high stability and a broad optical transparency window.These findings indicate that Hg_(2)Ga(Se_(O)_(3))_(2)F is a promising candidate for birefringent material in the mid-infrared(MIR)range.Our research provides an innovative strategy for improving the birefringence of compounds.展开更多
As an emerging microscopic detection tool,quantum microscopes based on the principle of quantum precision measurement have attracted widespread attention in recent years.Compared with the imaging of classical light,qu...As an emerging microscopic detection tool,quantum microscopes based on the principle of quantum precision measurement have attracted widespread attention in recent years.Compared with the imaging of classical light,quantum-enhanced imaging can achieve ultra-high resolution,ultra-sensitive detection,and anti-interference imaging.Here,we introduce a quantum-enhanced scanning microscope under illumination of an entangled NOON state in polarization.For the phase imager with NOON states,we propose a simple four-basis projection method to replace the four-step phase-shifting method.We have achieved the phase imaging of micrometer-sized birefringent samples and biological cell specimens,with sensitivity close to the Heisenberg limit.The visibility of transmittance-based imaging shows a great enhancement for NOON states.Besides,we also demonstrate that the scanning imaging with NOON states enables the spatial resolution enhancement of√N compared with classical measurement.Our imaging method may provide some reference for the practical application of quantum imaging and is expected to promote the development of microscopic detection.展开更多
We investigate the behavior of non-Hermitian birefringent Dirac fermions by examining their interaction with electromagnetic fields through renormalization group analysis. Our research reveals that the interplay betwe...We investigate the behavior of non-Hermitian birefringent Dirac fermions by examining their interaction with electromagnetic fields through renormalization group analysis. Our research reveals that the interplay between non-Hermiticity and birefringence leads to distinct behaviors in two and three dimensions, where the system exhibits different fixed points and scaling properties due to dimension-dependent charge renormalization effects. In two dimensions, where the electronic charge remains unrenormalized, the system flows in the deep infrared limit from non-Hermitian birefringent spin-3/2fermions to two copies of non-Hermitian spin-1/2 Dirac fermions, demonstrating a crossover of relativistic liquid and nonrelativistic liquid. In three dimensions, dynamic screening of electromagnetic interactions modifies the logarithmic growth of Fermi velocity, leading to richer quantum corrections while maintaining similar suppression of birefringence in the infrared limit. Our findings provide theoretical insights into the emergence of Lorentz symmetry in non-Hermitian systems,laying theoretical foundations for studying low-energy behavior in other non-Hermitian models.展开更多
The system consisting of(2+1)-dimensional quasirelativistic birefringent Dirac fermions with Coulomb interactions and retarded current–current interactions is described by a quantum field theory similar to reduced qu...The system consisting of(2+1)-dimensional quasirelativistic birefringent Dirac fermions with Coulomb interactions and retarded current–current interactions is described by a quantum field theory similar to reduced quantum electrodynamics.We used the perturbative renormalization group method to study the low-energy behavior of the system and found that it flows to a fixed point of the non-Fermi liquid composed of relativistic pseudospin-1/2 Dirac fermions in the deep infrared limit.At the fixed point,the fermion Green function exhibits a finite anomalous dimension,and the residue of the quasiparticle pole vanishes in a power-law fashion.Our research provides new theoretical perspectives for understanding the origin of spin-1/2 fermions in the standard model.展开更多
The collision characteristics of the orthogonally polarized solitons with initial linear frequency chirp in the linear birefringent fibre for β2 〈 0 are numerically studied. It is found that initial chirp changes th...The collision characteristics of the orthogonally polarized solitons with initial linear frequency chirp in the linear birefringent fibre for β2 〈 0 are numerically studied. It is found that initial chirp changes the threshold value of solitons to form the bound-state in the birefringent fibre. The effect of initial positive chirp on the threshold value is more obvious than that of negative chirp. In the case of （δ= 0.7 and initial interval 2τ0 = 1.25, the two solitons are mutually bound for 0.2 ≤ C ≤ 1, and they do not form the bound-state for -1 ≤ C 〈 0.2. Frequency shifts increase with the increase of chirp parameter C for -1 ≤ C 〈 0.2, and have the oscillatory structure for C ≥ 0.2. The effect of positive chirp on temporal FWHM is greater than that of negative chirp. The peak of temporal waveform oscillates with the propagation distance. The period and amplitude of the oscillation for the chirped case are greater than those for the unchirped case, and they vary with the increase of ｜C｜. The peak of output temporal waveform can be controlled by changing the initial chirp.展开更多
Visual cryptography is a method of encrypting an image into several encrypted images. Conventional visual cryptography can display only monochrome images. We previously proposed a color visual cryptography method that...Visual cryptography is a method of encrypting an image into several encrypted images. Conventional visual cryptography can display only monochrome images. We previously proposed a color visual cryptography method that uses the interference color of high-order retarder films and encrypts one secret image into two encrypted images. In other words, this method can only encrypt one image at a time. In this paper, we propose a new method that encrypts two color images using interference color.展开更多
The ultimate theme of this study is to develop dipole and combo optical solitons in birefringent fibers(BF) along with the effect of four-wave mixing(4 WM). Two types of rough mediums are used which are Kerr law and p...The ultimate theme of this study is to develop dipole and combo optical solitons in birefringent fibers(BF) along with the effect of four-wave mixing(4 WM). Two types of rough mediums are used which are Kerr law and parabolic law. Ansatz method of Choudhuri is applied to obtain dark in the bright(dipole) soliton solutions providing bright background for the propagation of optical dark pulse. Ansatz method of Li is applied to obtain combo soliton solutions providing bright solitary wave and dark solitary wave solutions. These results also exist to hold in non-Kerr media with higher order dispersion.展开更多
The output characteristics of optical feedback in a helium neon laser with a birefringent internal cavity are studied systematically in five different regions of the gain curve for the two orthogonally polarized modes...The output characteristics of optical feedback in a helium neon laser with a birefringent internal cavity are studied systematically in five different regions of the gain curve for the two orthogonally polarized modes. When the laser operates in the two end regions of the laser gain curve, one of the two orthogonally polarized modes will be a leading one in optical feedback. Strong mode competition can be observed. However, when the laser operates in the middle region of the laser gain curve, the two modes can oscillate equally with optical feedback. Besides the intensity of the two polarized lights, the total light intensity is also studied at the same time. M-shaped optical feedback curves are found. Particularly, when the average intensities of the two lights are comparable, the intensity modulation curve of the total light is doubled, which can be used to improve the resolution of an optical feedback system.展开更多
By adjusting the polarisation state of the pump at 805 nm parallel to slow （x） and fast （y） axes of the highly birefringent photonic crystal fibre with zero dispersion wavelengths 790 nm and 750 nm, this paper dem...By adjusting the polarisation state of the pump at 805 nm parallel to slow （x） and fast （y） axes of the highly birefringent photonic crystal fibre with zero dispersion wavelengths 790 nm and 750 nm, this paper demonstrates the efficient polarisation-sensitive four wave mixing involved in pump, anti-Stokes and Stokes signals and soliton self- frequency shift effects induced by the phase-matching between red-shifted solitons and blue-shifted dispersive waves. If the reduction of coupling efficiency to the circular pump laser mode or other circular fibres due to asymmetry of the core is neglected, more than 98% of the total input power is kept in a single linear polarisation. Controlled dispersion characteristic of the doublet of fundamental guided-modes results in achieving light field strongly confined in principal axes of photonic crystal fibre, and enhancing the corresponding nonlinear-optical process through the remarkable nonlinear birefringence.展开更多
We investigate the influence of the birefringence on the high-order harmonics in an a-cut Zn O crystal with midinfrared laser pulses.The high harmonics exhibit strong dependence on the alignment of the crystal with re...We investigate the influence of the birefringence on the high-order harmonics in an a-cut Zn O crystal with midinfrared laser pulses.The high harmonics exhibit strong dependence on the alignment of the crystal with respect to the laser polarization.We introduce the Jones calculus to counteract the birefringent effect and obtain the harmonics with polarization corrections in Zn O.We show that the birefringent effect plays an important role in the orientation dependence of HHG.展开更多
This paper reports that a 5-cm length birefringent photonic crystal fibre is used to tune the output frequency of unamplified 10-fs Ti：sapphire pulses. The zero dispersion of the fibre is at 823 nm and 800 nm for slo...This paper reports that a 5-cm length birefringent photonic crystal fibre is used to tune the output frequency of unamplified 10-fs Ti：sapphire pulses. The zero dispersion of the fibre is at 823 nm and 800 nm for slow and fast fundamental modes, respectively. It is demonstrated that efficient upshift of the output frequency can be achieved when the pumped radiation is polarized along the slow axis of the fibre. When the average input power reaches 320 mW, about 60% of the output energy is located in one peak at 600 nm and is accompanied by depletion of the pulse inside the anomalous dispersion region.展开更多
The effect of third order dispersion on pulse transmission is discussed. The coupled nonlinear Schrdinger equations characterizing the birefringent single mode fibers is solved numerically with combined consideratio...The effect of third order dispersion on pulse transmission is discussed. The coupled nonlinear Schrdinger equations characterizing the birefringent single mode fibers is solved numerically with combined consideration on chromatic dispersion, including second and third order dispersions, polarization mode dispersion (PMD) and nonlinearity. Various simulation results are presented.展开更多
Previous studies on modulation instabilities（MIs） in birefringent optical fibers focus on the ordinary linearly and circularly ones. This paper reports an analysis of MIs in the general elliptically birefringent fib...Previous studies on modulation instabilities（MIs） in birefringent optical fibers focus on the ordinary linearly and circularly ones. This paper reports an analysis of MIs in the general elliptically birefringent fibers with the emphasis on investigating the effects of ellipticity angle（0？ ≤θ≤ 90？）. Both symmetric and antisymmetric CW states are considered. In the anomalous dispersion regime, for the symmetric（antisymmetric） CW states, we show that MI gain increases dramatically（reduces first and then enhances greatly） as the increment of θ. In the normal dispersion regime, for the both CW states, the distinctive feature is that the gain of the MI bands reduces first, vanishes at θ = 45？,reappears across this ellipticity angle, and quickly increases after then.展开更多
We have investigated the effect of size parameter of the scatterer on the image quality obtained with polarization-based range-gated imaging in birefringent turbid medium. Both linearly and circularly polarized light ...We have investigated the effect of size parameter of the scatterer on the image quality obtained with polarization-based range-gated imaging in birefringent turbid medium. Both linearly and circularly polarized light were utilized for imaging.The simulated results indicate that the improvement of visibility is more pronounced using circularly polarized light for the birefringent medium composed of smaller-sized scatterers at lower values of optical thickness and the birefringent medium comprising larger-sized scatterers. In contrast, linearly polarized light provides better image quality for the birefringent medium composed of smaller-sized scatterers at larger values of optical thickness. The evolution of the polarization characteristics of backscattered light and target light under the conditions mentioned above was measured to account for these numerical results.展开更多
The propagation properties of the breather in birefringent fibers are investigated. The breather can propagate stably in strongly birefringent fibers. The propagation law can be expected. However, random birefringence...The propagation properties of the breather in birefringent fibers are investigated. The breather can propagate stably in strongly birefringent fibers. The propagation law can be expected. However, random birefringence makes the propagation of the breather more complex. The breather will partly disappear and partly appear, even may split into two smaller breathers. In addition, the varying range of relative time displacement between two components of the breather becomes narrower with the effect of third-order dispersion. If third order dispersion is too strong, the breather behavior will disappear gradually during the transmission. The breather can exist in random birefringent fiber with dispersion management rather than in strongly birefringent fiber.展开更多
In this paper, a novel photonic crystal fiber （PCF） with high birefringence and nonlinearity is designed. The charac- teristics of birefringence, dispersion and nonlinearity are studied by using the full-vector fini...In this paper, a novel photonic crystal fiber （PCF） with high birefringence and nonlinearity is designed. The charac- teristics of birefringence, dispersion and nonlinearity are studied by using the full-vector finite element method （FVFEM）. The numerical results show that the phase birefringence and nonlinear coefficient of PCF can be up to 4.51× 10-3 and 32.8972 w-l.km-1 at 1.55 μm, respectively. The proposed PCF could be found to have important applications in the polarization-dependent nonlinear optics such as the pulse compress and reshaping in the C waveband.展开更多
Highly nonlinear birefringent Photonic Crystal Fibre (PCF) that exhibits low losses and small effective mode area across a wide wavelength range has been presented. The effects of angular orientation on bending losses...Highly nonlinear birefringent Photonic Crystal Fibre (PCF) that exhibits low losses and small effective mode area across a wide wavelength range has been presented. The effects of angular orientation on bending losses of the proposed PCFs have been thoroughly investigated by employing a full vectorial finite element method (FEM). It has been demonstrated that it is possible to design a bending-insensitive nonlinear PCF with a birefringence in the order of 10-2 and a nonlinear coefficient of 49 W-1km-1 at the wavelength of 1.55 μm. Also, significant improvements on key propagation characteristics of the proposed PCFs have been demonstrated by carefully altering the desired air hole diameters and the hole-to-hole spacing. It is demonstrated that two zero dispersion wavelengths can be achieved by the proposed design.展开更多
A novel photoresponding ionic complex （PANDAZO） was prepared by the ionic self-assembly （1SA） of sodium polyacrylate （PANa） and azobenzene chromophores （NDAZO）. The ionic complex forms an interdigitated lamell...A novel photoresponding ionic complex （PANDAZO） was prepared by the ionic self-assembly （1SA） of sodium polyacrylate （PANa） and azobenzene chromophores （NDAZO）. The ionic complex forms an interdigitated lamellar structure with full overlap of the side chains. The optical anisotropy was investigated by using a polarization pulse laser （355 nm）. Furthermore, a high photoinduced birefringence （An = 0.365） was measured by using a continuous 488 nm laser as the pump light.展开更多
This paper presents the development of a highly efficient CT-PCF (Core-Tune Photonic Crystal Fiber) with substantial birefringence, tailored for applications in high-bit-rate communication and sensing while minimizing...This paper presents the development of a highly efficient CT-PCF (Core-Tune Photonic Crystal Fiber) with substantial birefringence, tailored for applications in high-bit-rate communication and sensing while minimizing signal loss. The design incorporates a modified broadband dispersion compensating structure, optimized for operation across the E, S, C, and L communication bands within a wavelength range spanning 1360 nm to 1625 nm. Notably, the CT-PCF demonstrates a remarkable birefringence of 2.372 × 10<sup>-2</sup> at 1550 nm, surpassing traditional PCF structures. Single-mode performance is evaluated using the Higher Order Mode Extinction Ratio (HOMER) method, revealing a peak HOMER value of 10<sup>4</sup> at 1550 nm. Furthermore, at 1550 nm, the CT-PCF exhibits exceptional nonlinear characteristics, featuring a high nonlinearity of 50.74 W<sup>-1</sup>⋅Km<sup>-1</sup> for y polarization. In comparison to existing designs, the proposed CT-PCF exhibits superior performance metrics and optical characteristics. Additionally, the y polarization dispersion coefficient of the CT-PCF at 1550 nm is measured at -3534 ps/(nm⋅km). Overall, the CT-PCF represents a significant advancement, outperforming established systems in terms of performance metrics and optical properties.展开更多
基金supported by the National Natural Science Foundation of China(Nos.22475215,22031009 and 21921001)the NSF of Fujian Province(Nos.2023J01216,2024J010039)the Selfdeployment Project Research Program of Haixi Institutes,Chinese Academy of Sciences(No.CXZX-2022-GH06).
文摘Exploring new material systems and enhancing the birefringence of compounds is a highly valuable endeavor.In this study,we introduce a novel method to enhance the birefringence of inorganic compounds by inducing structural alignment through linear groups and fluoride ions.We report on two new compounds:HgGa_(2)(SeO_(3))_(4) and Hg_(2)Ga(Se_(O)_(3))_(2)F.HgGa_(2)(SeO_(3))_(4) crystallizes in a non-centrosymmetric(NCS)space group,exhibiting a second harmonic generation(SHG)efficiency of approximately 60% that of commercial KH2PO4(KDP),with a birefringence of 0.032@546 nm.Hg_(2)Ga(Se_(O)_(3))_(2)F,on the other hand,crystallizes in a centrosymmetric space(CS)group and represents the first reported HgI-based selenite birefringent material.Due to the influence of the linear group Hg_(2)O_(2),its birefringence is significantly enhanced to 0.111@546 nm,which is 3.5 times that of HgGa_(2)(SeO_(3))_(4).Moreover,both compounds demonstrate high stability and a broad optical transparency window.These findings indicate that Hg_(2)Ga(Se_(O)_(3))_(2)F is a promising candidate for birefringent material in the mid-infrared(MIR)range.Our research provides an innovative strategy for improving the birefringence of compounds.
基金supported by he National Natural Science Foundation of China(Grant Nos.12304359,12304398,12404382,12234009,12274215,and 12427808)the China Postdoctoral Science Foundation(Grant No.2023M731611)+4 种基金the Jiangsu Funding Program for Excellent Postdoctoral Talent(Grant No.2023ZB717)Innovation Program for Quantum Science and Technology(Grant No.2021ZD0301400)Key R&D Program of Jiangsu Province(Grant No.BE2023002)Natural Science Foundation of Jiangsu Province(Grant Nos.BK20220759 and BK20233001)Program for Innovative Talents and Entrepreneurs in Jiangsu,and Key R&D Program of Guangdong Province(Grant No.2020B0303010001).
文摘As an emerging microscopic detection tool,quantum microscopes based on the principle of quantum precision measurement have attracted widespread attention in recent years.Compared with the imaging of classical light,quantum-enhanced imaging can achieve ultra-high resolution,ultra-sensitive detection,and anti-interference imaging.Here,we introduce a quantum-enhanced scanning microscope under illumination of an entangled NOON state in polarization.For the phase imager with NOON states,we propose a simple four-basis projection method to replace the four-step phase-shifting method.We have achieved the phase imaging of micrometer-sized birefringent samples and biological cell specimens,with sensitivity close to the Heisenberg limit.The visibility of transmittance-based imaging shows a great enhancement for NOON states.Besides,we also demonstrate that the scanning imaging with NOON states enables the spatial resolution enhancement of√N compared with classical measurement.Our imaging method may provide some reference for the practical application of quantum imaging and is expected to promote the development of microscopic detection.
基金Project supported by the National Key Research and Development Program of China (Grants Nos. 2021YFA1400900,2021YFA0718300, and 2021YFA1400243)the National Natural Science Foundation of China (Grant Nos. 61835013,12174461, and 12234012)the Fund from the Space Application System of China Manned Space Program。
文摘We investigate the behavior of non-Hermitian birefringent Dirac fermions by examining their interaction with electromagnetic fields through renormalization group analysis. Our research reveals that the interplay between non-Hermiticity and birefringence leads to distinct behaviors in two and three dimensions, where the system exhibits different fixed points and scaling properties due to dimension-dependent charge renormalization effects. In two dimensions, where the electronic charge remains unrenormalized, the system flows in the deep infrared limit from non-Hermitian birefringent spin-3/2fermions to two copies of non-Hermitian spin-1/2 Dirac fermions, demonstrating a crossover of relativistic liquid and nonrelativistic liquid. In three dimensions, dynamic screening of electromagnetic interactions modifies the logarithmic growth of Fermi velocity, leading to richer quantum corrections while maintaining similar suppression of birefringence in the infrared limit. Our findings provide theoretical insights into the emergence of Lorentz symmetry in non-Hermitian systems,laying theoretical foundations for studying low-energy behavior in other non-Hermitian models.
基金supported by the National Key Research and Development Program of China(Grant Nos.2021YFA1400900,2021YFA0718300,and 2021YFA1400243)the National Natural Science Foundation of China(Grant Nos.61835013,12174461,and 12234012)Space Application System of China Manned Space Program.
文摘The system consisting of(2+1)-dimensional quasirelativistic birefringent Dirac fermions with Coulomb interactions and retarded current–current interactions is described by a quantum field theory similar to reduced quantum electrodynamics.We used the perturbative renormalization group method to study the low-energy behavior of the system and found that it flows to a fixed point of the non-Fermi liquid composed of relativistic pseudospin-1/2 Dirac fermions in the deep infrared limit.At the fixed point,the fermion Green function exhibits a finite anomalous dimension,and the residue of the quasiparticle pole vanishes in a power-law fashion.Our research provides new theoretical perspectives for understanding the origin of spin-1/2 fermions in the standard model.
文摘The collision characteristics of the orthogonally polarized solitons with initial linear frequency chirp in the linear birefringent fibre for β2 〈 0 are numerically studied. It is found that initial chirp changes the threshold value of solitons to form the bound-state in the birefringent fibre. The effect of initial positive chirp on the threshold value is more obvious than that of negative chirp. In the case of （δ= 0.7 and initial interval 2τ0 = 1.25, the two solitons are mutually bound for 0.2 ≤ C ≤ 1, and they do not form the bound-state for -1 ≤ C 〈 0.2. Frequency shifts increase with the increase of chirp parameter C for -1 ≤ C 〈 0.2, and have the oscillatory structure for C ≥ 0.2. The effect of positive chirp on temporal FWHM is greater than that of negative chirp. The peak of temporal waveform oscillates with the propagation distance. The period and amplitude of the oscillation for the chirped case are greater than those for the unchirped case, and they vary with the increase of ｜C｜. The peak of output temporal waveform can be controlled by changing the initial chirp.
文摘Visual cryptography is a method of encrypting an image into several encrypted images. Conventional visual cryptography can display only monochrome images. We previously proposed a color visual cryptography method that uses the interference color of high-order retarder films and encrypts one secret image into two encrypted images. In other words, this method can only encrypt one image at a time. In this paper, we propose a new method that encrypts two color images using interference color.
文摘The ultimate theme of this study is to develop dipole and combo optical solitons in birefringent fibers(BF) along with the effect of four-wave mixing(4 WM). Two types of rough mediums are used which are Kerr law and parabolic law. Ansatz method of Choudhuri is applied to obtain dark in the bright(dipole) soliton solutions providing bright background for the propagation of optical dark pulse. Ansatz method of Li is applied to obtain combo soliton solutions providing bright solitary wave and dark solitary wave solutions. These results also exist to hold in non-Kerr media with higher order dispersion.
基金Project supported by the Major Program of the National Natural Science Foundation of China （Grant No 60438010）.
文摘The output characteristics of optical feedback in a helium neon laser with a birefringent internal cavity are studied systematically in five different regions of the gain curve for the two orthogonally polarized modes. When the laser operates in the two end regions of the laser gain curve, one of the two orthogonally polarized modes will be a leading one in optical feedback. Strong mode competition can be observed. However, when the laser operates in the middle region of the laser gain curve, the two modes can oscillate equally with optical feedback. Besides the intensity of the two polarized lights, the total light intensity is also studied at the same time. M-shaped optical feedback curves are found. Particularly, when the average intensities of the two lights are comparable, the intensity modulation curve of the total light is doubled, which can be used to improve the resolution of an optical feedback system.
基金partly supported by the National Basic Research Program (Grant Nos. 2010CB327605 and 2010CB328300)Nationa lHigh-Technology Research and Development Program of China (Grant Nos. 2007AA03Z447 and 2009AA01Z220)+2 种基金the National Natural Science Foundation of China (Grant No. 60807022)the Key Grant of Ministry of Education of China (Grant No. 109015)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20070013001)
文摘By adjusting the polarisation state of the pump at 805 nm parallel to slow （x） and fast （y） axes of the highly birefringent photonic crystal fibre with zero dispersion wavelengths 790 nm and 750 nm, this paper demonstrates the efficient polarisation-sensitive four wave mixing involved in pump, anti-Stokes and Stokes signals and soliton self- frequency shift effects induced by the phase-matching between red-shifted solitons and blue-shifted dispersive waves. If the reduction of coupling efficiency to the circular pump laser mode or other circular fibres due to asymmetry of the core is neglected, more than 98% of the total input power is kept in a single linear polarisation. Controlled dispersion characteristic of the doublet of fundamental guided-modes results in achieving light field strongly confined in principal axes of photonic crystal fibre, and enhancing the corresponding nonlinear-optical process through the remarkable nonlinear birefringence.
基金the National Natural Science Foundation of China(Grant Nos.91950202,11627809,11874165,11934006,11774109,and 12021004)。
文摘We investigate the influence of the birefringence on the high-order harmonics in an a-cut Zn O crystal with midinfrared laser pulses.The high harmonics exhibit strong dependence on the alignment of the crystal with respect to the laser polarization.We introduce the Jones calculus to counteract the birefringent effect and obtain the harmonics with polarization corrections in Zn O.We show that the birefringent effect plays an important role in the orientation dependence of HHG.
基金supported by the National Natural Science Foundation of China(Grant Nos 10874145 and 60490280)the China Postdoctoral Science Foundation(Grant No 20080440014)the Yanshan University Doctor Foundation of China(Grant No B153)
文摘This paper reports that a 5-cm length birefringent photonic crystal fibre is used to tune the output frequency of unamplified 10-fs Ti：sapphire pulses. The zero dispersion of the fibre is at 823 nm and 800 nm for slow and fast fundamental modes, respectively. It is demonstrated that efficient upshift of the output frequency can be achieved when the pumped radiation is polarized along the slow axis of the fibre. When the average input power reaches 320 mW, about 60% of the output energy is located in one peak at 600 nm and is accompanied by depletion of the pulse inside the anomalous dispersion region.
文摘The effect of third order dispersion on pulse transmission is discussed. The coupled nonlinear Schrdinger equations characterizing the birefringent single mode fibers is solved numerically with combined consideration on chromatic dispersion, including second and third order dispersions, polarization mode dispersion (PMD) and nonlinearity. Various simulation results are presented.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11447113 and 11305031 Natural Science Foundation of Jiangsu Provincial Universities under Grant No.14KJB140009 the Startup Foundation for Introducing Talent of Nanjing University of Information Science and Technology under Grant No.2241131301064
文摘Previous studies on modulation instabilities（MIs） in birefringent optical fibers focus on the ordinary linearly and circularly ones. This paper reports an analysis of MIs in the general elliptically birefringent fibers with the emphasis on investigating the effects of ellipticity angle（0？ ≤θ≤ 90？）. Both symmetric and antisymmetric CW states are considered. In the anomalous dispersion regime, for the symmetric（antisymmetric） CW states, we show that MI gain increases dramatically（reduces first and then enhances greatly） as the increment of θ. In the normal dispersion regime, for the both CW states, the distinctive feature is that the gain of the MI bands reduces first, vanishes at θ = 45？,reappears across this ellipticity angle, and quickly increases after then.
基金Project supported by China Postdoctoral Science Foundation(Grant No.2016M592788)the Natural Science Basic Research Plan in Shaanxi Province of China(Grant No.2018JM6008)
文摘We have investigated the effect of size parameter of the scatterer on the image quality obtained with polarization-based range-gated imaging in birefringent turbid medium. Both linearly and circularly polarized light were utilized for imaging.The simulated results indicate that the improvement of visibility is more pronounced using circularly polarized light for the birefringent medium composed of smaller-sized scatterers at lower values of optical thickness and the birefringent medium comprising larger-sized scatterers. In contrast, linearly polarized light provides better image quality for the birefringent medium composed of smaller-sized scatterers at larger values of optical thickness. The evolution of the polarization characteristics of backscattered light and target light under the conditions mentioned above was measured to account for these numerical results.
文摘The propagation properties of the breather in birefringent fibers are investigated. The breather can propagate stably in strongly birefringent fibers. The propagation law can be expected. However, random birefringence makes the propagation of the breather more complex. The breather will partly disappear and partly appear, even may split into two smaller breathers. In addition, the varying range of relative time displacement between two components of the breather becomes narrower with the effect of third-order dispersion. If third order dispersion is too strong, the breather behavior will disappear gradually during the transmission. The breather can exist in random birefringent fiber with dispersion management rather than in strongly birefringent fiber.
基金Project partly supported by the State Major Basic Research Development Program of China(Grant No.2010CB327604)the National Natural Science Foundation of China(Grant No.61377100)
文摘In this paper, a novel photonic crystal fiber （PCF） with high birefringence and nonlinearity is designed. The charac- teristics of birefringence, dispersion and nonlinearity are studied by using the full-vector finite element method （FVFEM）. The numerical results show that the phase birefringence and nonlinear coefficient of PCF can be up to 4.51× 10-3 and 32.8972 w-l.km-1 at 1.55 μm, respectively. The proposed PCF could be found to have important applications in the polarization-dependent nonlinear optics such as the pulse compress and reshaping in the C waveband.
文摘Highly nonlinear birefringent Photonic Crystal Fibre (PCF) that exhibits low losses and small effective mode area across a wide wavelength range has been presented. The effects of angular orientation on bending losses of the proposed PCFs have been thoroughly investigated by employing a full vectorial finite element method (FEM). It has been demonstrated that it is possible to design a bending-insensitive nonlinear PCF with a birefringence in the order of 10-2 and a nonlinear coefficient of 49 W-1km-1 at the wavelength of 1.55 μm. Also, significant improvements on key propagation characteristics of the proposed PCFs have been demonstrated by carefully altering the desired air hole diameters and the hole-to-hole spacing. It is demonstrated that two zero dispersion wavelengths can be achieved by the proposed design.
基金financial support from the National Science Fund for Distinguished Young Scholars(No.50925310)the National Science Foundation of China(Nos.50902094 and 51173103)+1 种基金the 973 Project(Nos.2009CB93043 and 2012CB933803)the Excellent Academic Leaders of Shanghai(No.11XD1403000)
文摘A novel photoresponding ionic complex （PANDAZO） was prepared by the ionic self-assembly （1SA） of sodium polyacrylate （PANa） and azobenzene chromophores （NDAZO）. The ionic complex forms an interdigitated lamellar structure with full overlap of the side chains. The optical anisotropy was investigated by using a polarization pulse laser （355 nm）. Furthermore, a high photoinduced birefringence （An = 0.365） was measured by using a continuous 488 nm laser as the pump light.
文摘This paper presents the development of a highly efficient CT-PCF (Core-Tune Photonic Crystal Fiber) with substantial birefringence, tailored for applications in high-bit-rate communication and sensing while minimizing signal loss. The design incorporates a modified broadband dispersion compensating structure, optimized for operation across the E, S, C, and L communication bands within a wavelength range spanning 1360 nm to 1625 nm. Notably, the CT-PCF demonstrates a remarkable birefringence of 2.372 × 10<sup>-2</sup> at 1550 nm, surpassing traditional PCF structures. Single-mode performance is evaluated using the Higher Order Mode Extinction Ratio (HOMER) method, revealing a peak HOMER value of 10<sup>4</sup> at 1550 nm. Furthermore, at 1550 nm, the CT-PCF exhibits exceptional nonlinear characteristics, featuring a high nonlinearity of 50.74 W<sup>-1</sup>⋅Km<sup>-1</sup> for y polarization. In comparison to existing designs, the proposed CT-PCF exhibits superior performance metrics and optical characteristics. Additionally, the y polarization dispersion coefficient of the CT-PCF at 1550 nm is measured at -3534 ps/(nm⋅km). Overall, the CT-PCF represents a significant advancement, outperforming established systems in terms of performance metrics and optical properties.
