A band-pass frequency selective surface(FSS) with polarization rotation property is proposed. The proposed polarization rotating FSS(PR-FSS) is a two-dimensional periodic structure, its unit cell is an antenna-filter-...A band-pass frequency selective surface(FSS) with polarization rotation property is proposed. The proposed polarization rotating FSS(PR-FSS) is a two-dimensional periodic structure, its unit cell is an antenna-filter-antenna(AFA) module,and the polarization directions of the upper and lower antennas in each AFA module are orthogonal to each other, so the PR-FSS can achieve frequency selection and 90 degrees polarization rotation at the same time. The numerical simulation demonstrate that the anticipated frequency selection and polarization rotation are realized by the PR-FSS in the frequency band from 8.84 GHz to 10.30 GHz with a relative bandwidth of 15.26%, and the maximum insertion loss in the pass band is only 0.17 d B. Finally, one effective experiment validation is carried out, a reasonable agreement is observed between the experimental and simulated results except for a slight deviation caused by fabrication error and measurement tolerance.展开更多
Taking into account ultra-fast carrier dynamics, this paper models 640 Gbit/s wavelength conversion scheme based on nonlinear polarization rotation (NPR) in a single semiconductor optical amplifier (SOA) and inves...Taking into account ultra-fast carrier dynamics, this paper models 640 Gbit/s wavelength conversion scheme based on nonlinear polarization rotation (NPR) in a single semiconductor optical amplifier (SOA) and investigates the performance of this kind of wavelength conversion scheme in detail. In this model, two carrier temperature equations are introduced to substitute two energy density equations, which reduce the complexity of calculation in comparison with the previous model. The temporary gain and phase shift dynamics induced by ultra-short optical pulses are numerically simulated and the simulated results are qualitatively in good agreement with reported experimental results. Simulated results show that non-inverted and inverted 640 Gbit/s wavelength conversions based on NPR are achieved with clear open eye diagrams. To further investigate the performance of the non-inverted wavelength conversion scheme, the dependence of output extinction ratio (ER) on some key parameters used in simulation is illustrated. Furthermore, simulated analyses show that high performance non-inverted wavelength conversion based on NPR can be achieved by using a red-shifted filtering scheme.展开更多
A theoretical model of the refractive index changes of the TE and TM modes in an electro-absorption modulator (EAM) is deduced. The photon absorption and refractive index changes are analyzed numerically. The influe...A theoretical model of the refractive index changes of the TE and TM modes in an electro-absorption modulator (EAM) is deduced. The photon absorption and refractive index changes are analyzed numerically. The influence of pump intensity on the phase difference between the TE and TM modes is studied. The polarization rotation effect is obtained in the EAM, and a novel all-optical fiber loop buffer is designed.展开更多
Polarization rotation and vector field steering of electromagnetic wave are of great significance in modern optical applications.However,conventional polarization devices are bulky,monofunctional and lack of tunabilit...Polarization rotation and vector field steering of electromagnetic wave are of great significance in modern optical applications.However,conventional polarization devices are bulky,monofunctional and lack of tunability,which pose great challenges to the miniaturized and multifunctional applications.Herein,we propose a meta-device that is capable of multi-state polarization rotation and vector field steering based on phase change metasurface.The supercell of the meta-device consists of four Ge2Sb2Te5(GST)elliptic cylinders located on a SiO2 substrate.By independently controlling the phase state(amorphous or crystalline)of each GST elliptic cylinder,the meta-device can rotate the polarization plane of the linearly polarized incident light to different angles that cover from 19.8°to 154.9°at a wavelength of 1550 nm.Furthermore,by merely altering the phase transition state of GST elliptic cylinders,we successfully demonstrated a vector field steering by generating optical vortices carrying orbital angular momentums(OAMs)with topological charges of 0,1 and–1,respectively.The proposed method provides a new platform for investigating dynamically tunable optical devices and has potential applications in many fields such as optical communications and information processing.展开更多
A catadioptric lens structure,also known as pancake lens,has been widely used in virtual reality(VR)displays to reduce the formfactor.However,the utilization of a half mirror(HM)to fold the optical path thrice leads t...A catadioptric lens structure,also known as pancake lens,has been widely used in virtual reality(VR)displays to reduce the formfactor.However,the utilization of a half mirror(HM)to fold the optical path thrice leads to a significant optical loss.The theoretical maximum optical efficiency is merely 25%.To transcend this optical efficiency constraint while retaining the foldable characteristic inherent to traditional pancake optics,in this paper,we propose a theoretically lossless folded optical system to replace the HM with a nonreciprocal polarization rotator.In our feasibility demonstration experiment,we used a commercial Faraday rotator(FR)and reflective polarizers to replace the lossy HM.The theoretically predicted 100%efficiency can be achieved approximately by using two high-extinction-ratio reflective polarizers.In addition,we evaluated the ghost images using a micro-OLED panel in our imaging system.Indeed,the ghost images can be suppressed to undetectable level if the optics are with antireflection coating.Our novel pancake optical system holds great potential for revolutionizing next-generation VR displays with lightweight,compact formfactor,and low power consumption.展开更多
A mode-locked thulium-doped fiber laser(TDFL) based on nonlinear polarization rotation(NPR) with different net anomalous dispersion is demonstrated. When the cavity dispersion is-1.425 ps^2, the noise-like(NL) pulse w...A mode-locked thulium-doped fiber laser(TDFL) based on nonlinear polarization rotation(NPR) with different net anomalous dispersion is demonstrated. When the cavity dispersion is-1.425 ps^2, the noise-like(NL) pulse with coherence spike width of 406 fs and pulse energy of 12.342 nJ is generated at a center wavelength of 2003.2 nm with 3 dB spectral bandwidth of 23.20 nm. In the experimental period of 400 min, the 3 dB spectral bandwidth variation, the output power fluctuation, and the central wavelength shift are less than 0.06 nm, 0.04 d B, and0.4 nm, respectively, indicating that the NPR-based TDFL operating in the NL regime holds good long-term stability.展开更多
We report the experimental demonstration of an ultranarrow bandwidth atomic filter by optically induced polarization rotation in multilevel electromagnetically induced transparency systems in hot Rb vapor. With a coup...We report the experimental demonstration of an ultranarrow bandwidth atomic filter by optically induced polarization rotation in multilevel electromagnetically induced transparency systems in hot Rb vapor. With a coupling intensity of 2.3 W/cm^2, the filter shows a peak transmission of 33.2% and a bandwidth of 10 MHz. By altering the coupling frequency, a broad tuning range of several Doppler linewidths of the D1 line transitions of STRb atoms can be obtained. The presented atomic filter has useful features of ultranarrow bandwidth, and the operating frequency can be tuned resonance with the atomic transition. Such narrowband tunable atomic filter can be used as an efficient noise rejection tool in classical and quantum optical applications.展开更多
A novel design of optical sampling system has been developed by using sum-frequency generation (SFG) in a periodically-poled lithium niobate (PPLN) waveguide and using passive mode-locked fiber laser pulses as opt...A novel design of optical sampling system has been developed by using sum-frequency generation (SFG) in a periodically-poled lithium niobate (PPLN) waveguide and using passive mode-locked fiber laser pulses as optical sampling pulses. The system achieved high temporal resolution and high sensitivity using a 30 mm length PPLN with quasi phase match period of 19.3 μm and 151 fs sampling pulses which were generated by passive modelock fiber laser based on nonlinear polarization rotation (NPR). Clear eye-diagram of 10 Gbit/s non-return-to-zeros (NRZ) pseudorandom binary sequence (PRBS) optical signal were successfully reconstructed by this system.展开更多
In this paper,we examine the tiny polarization rotation effect in total internal reflection due to the spin–orbit interaction of light.We find that the tiny polarization rotation rate will induce a geometric phase gr...In this paper,we examine the tiny polarization rotation effect in total internal reflection due to the spin–orbit interaction of light.We find that the tiny polarization rotation rate will induce a geometric phase gradient,which can be regarded as the physical origin of photonic spin Hall effect.We demonstrate that the spin-dependent splitting in position space is related to the polarization rotation in momentum space,while the spin-dependent splitting in momentum space is attributed to the polarization rotation in position space.Furthermore,we introduce a quantum weak measurement to determine the tiny polarization rotation rate.The rotation rate in momentum space is obtained with 118 nm,which manifests itself as a spatial shift,and the rotation rate in position space is achieved with 38 μrad∕λ,which manifests itself as an angular shift.The investigation of the polarization rotation characteristics will provide insights into the photonic spin Hall effect and will enable us to better understand the spin–orbit interaction of light.展开更多
We demonstrate the simultaneous temporal contrast improvement and pulse compression of a Yb-doped femtosecond laser via nonlinear elliptical polarization rotation in a solid state multi-pass cell.The temporal contrast...We demonstrate the simultaneous temporal contrast improvement and pulse compression of a Yb-doped femtosecond laser via nonlinear elliptical polarization rotation in a solid state multi-pass cell.The temporal contrast is improved to 109,while the pulse is shortened from 181 to 36 fs,corresponding to a compression factor of 5.The output beam features excellent beam quality with M^(2) values of 1.18×1.16.The total efficiency of the contrast enhancement system exceeds 50%.This technique will have wide applications in high temporal contrast ultra-intense femtosecond lasers.展开更多
The measurement of an extremely small magneto-optical polarization rotation angle with high sensitivity is integral to many scientific and technological applications. In this Letter, we have presented a technique base...The measurement of an extremely small magneto-optical polarization rotation angle with high sensitivity is integral to many scientific and technological applications. In this Letter, we have presented a technique based on Faraday modulation combined with the optical differential method to measure an extremely small polari- zation rotation angle with high sensitivity. The theoretical and experimental results show that common mode noise is reduced appreciably and signal to noise ratio is enhanced. The effectiveness of this technique has been demonstrated by measuring the Verdet constant of terbium gallium garnet glass and measuring the small polari- zation rotation angle. A sensitivity of enhancement of one order of magnitude has been achieved using differ- ential detection based on Faraday modulation.展开更多
This paper presents multiple-modes Scanning Probe Microscopy(SPM)studies on characterize the correlation of resistance switching(RS)and polarization rotation(PR)in copper doped ZnO(ZnO:Cu)thin films.Firstly,the bipola...This paper presents multiple-modes Scanning Probe Microscopy(SPM)studies on characterize the correlation of resistance switching(RS)and polarization rotation(PR)in copper doped ZnO(ZnO:Cu)thin films.Firstly,the bipolar RS behavior is confirmed by conductive Atomic Force Microscopy(c-AFM).The PR with almost 180phase angle is confirmed by using the Piezoresponse Force Microscopy(PFM)on the same location.In addition,it elucidates that obvious PR behavior can be observed in the sample with increasing Cu concentration by combining Kelvin Probe Force Microscopy(KPFM).Furthermore,it is found that the region with downward polarization has low resistance state(LRS),whereas the region with upward polarization has high resistance state(HRS).Moreover,the Piezoresponse Force Spectroscopy(PFS)and Switching Spectroscopy PFM(SS-PFM)measurements further confirm that the existence of the built-in voltage,V_(built-in) is largest in the ZnO:Cu(8 at.%)film deposited at the oxygen partial pressure of 2×10^(-4) Torr.The schematic diagrams of energy band diagram with varied built-in field,Ebuilt-in,polarization directions and redistributed charges are presented to explain the correlation between RS and PR behavior.展开更多
Diffraction-free vectorial elliptic hollow beams(vEHBs)are generated by an optical system composed of a short elliptic hollow fiber(EHF)and an axicon.Each beam has a closed elliptic annular intensity profile and space...Diffraction-free vectorial elliptic hollow beams(vEHBs)are generated by an optical system composed of a short elliptic hollow fiber(EHF)and an axicon.Each beam has a closed elliptic annular intensity profile and space-varying polarization states in its diffraction-free distance of more than 1 m.The generated beams have a counter-clockwise or clockwise periodically-rotated inhomogeneous polarization.And the spin angular momentum(SAM)of the vEHBs is 1ħor-1ħwhich is consistent with the type of dual-mode in the EHF and the periodic polarization rotations of the vEHBs.The vEHBs have potential applications in optically trapping and micromanipulating the micro-or nano-particles,quantum information transmission,and Bose-Einstein condensates,etc.展开更多
A new polarization rotator based on the silica photonic crystal fiber is proposed. The proposed polarization rotator photonic crystal fiber (PR-PCF) possesses a triangle jigsaw-shape core region. The full-vector fin...A new polarization rotator based on the silica photonic crystal fiber is proposed. The proposed polarization rotator photonic crystal fiber (PR-PCF) possesses a triangle jigsaw-shape core region. The full-vector finite-element method is used to analyze the phenomenon of polarization conversion between the quasi-TE and quasi-TM modes. Numerical simulations show that the wavelengths of 1.31 μm and 1.55 μm are converted with a nearly 100% polarization conversion ratio with their matched coupling length and has a relatively strong realistic fabrication tolerance - 100 nm on the y axis and 50 nm on the x axis. The full vectorial finite difference beam propagation method is used to confirm the performance of the proposed PR-PCF.展开更多
A frequency selective polarization rotator that can rotate the polarization angle of an incident electromagnetic wave at the microwave frequency by 45 is presented. The polarization rotator is based on a two-dimension...A frequency selective polarization rotator that can rotate the polarization angle of an incident electromagnetic wave at the microwave frequency by 45 is presented. The polarization rotator is based on a two-dimensional periodic array of substrate integrated waveguide cavities, realizing the polarization rotation by coupling the input signal to the output wave through three metallic slots. Two layers of frequency selective surfaces are cascaded by substrate and form the polarization rotator. A vertical slot on the top layer is used to select the horizontal polarization from the incident wave, the vertical and the horizontal slots on the bottom layer are, respectively, used to obtain horizontally and vertically polarized outgoing waves. The two orthogonal outgoing waves are combined to result in the 45~ polarized wave. Both full wave simulation and experimental measurement are carried out, together validating the proposed method.展开更多
Quasi-classical trajectory calculations are performed to study the stereodynamics of the H(~2S) + NH(a^1?) →H_2(X^1Σ_g~+) + N(~2D) reaction based on the first excited state NH_2(1~2A') potential energ...Quasi-classical trajectory calculations are performed to study the stereodynamics of the H(~2S) + NH(a^1?) →H_2(X^1Σ_g~+) + N(~2D) reaction based on the first excited state NH_2(1~2A') potential energy surface reported by Li et al.[Li Y Q and Varandas A J C 2010 J. Phys. Chem. A 114 9644] for the first time. We observe the changes of differential cross-sections at different collision energies and different initial reagent rotational excitations. The influence of collision energy on the k-k' distribution can be attributed to a purely impulsive effect. Initial reagent rotational excitation transforms the reaction mechanism from insertion to abstraction. The effect of initial reagent rotational excitations on k-k' distribution can be explained by the rotational excitation enlarging the rotational rate of reagent NH in the entrance channel to reduce the probability of collision between incidence H atom and H atom of target molecular. We also investigate the changes of vector correlations and find that the rotational angular momentum vector j' of the product H_2 is not only aligned, but also oriented along the y axis. The alignment parameter, the disposal of total angular momentum and the reaction mechanism are all analyzed carefully to explain the polarization behavior of the product rotational angular moment.展开更多
Silicon waveguides typically exhibit optical anisotropy,which leads to polarization correlation and single-polarization operations.This consequently creates a demand for polarization-control devices.This paper introdu...Silicon waveguides typically exhibit optical anisotropy,which leads to polarization correlation and single-polarization operations.This consequently creates a demand for polarization-control devices.This paper introduces a CMOS-compatible O-band reconfigurable TE/TM polarization rotator comprising two symmetrical polarization rotator-splitters and phase shifters.This configuration enables dynamic conversion of any linear polarization to its quadratic equivalent.Experimental results indicate that the reconfigurable polarization rotator exhibits an insertion loss of less than 1.5 dB.Furthermore,the bandwidth for a polarization extinction ratio beyond 15 dB exceeds 60 nm.展开更多
We experimentally demonstrated a stable multi-wavelength bright-dark pulse pair in a mode-locked thulium-doped fiber laser(TDFL).The nonlinear polarization rotation(NPR)and nonlinear optical loop mirror(NOLM)were empl...We experimentally demonstrated a stable multi-wavelength bright-dark pulse pair in a mode-locked thulium-doped fiber laser(TDFL).The nonlinear polarization rotation(NPR)and nonlinear optical loop mirror(NOLM)were employed in a figure-eight cavity to allow for multi-wavelength mode-locking operation.By incorporating different lengths of high birefringence polarization-maintaining fiber(PMF),the fiber laser could operate stably in a multi-wavelength emission state.Compared with the absence of the PMF,the birefringence effect caused by PMF resulted in rich multi-wavelength optical spectra and better intensity symmetry and stability of the bright-dark pulse pair.展开更多
We report on a theoretical and experimental study of an all-normal-dispersion (ANDi) Yb-doped mode-locked fiber laser, in which nonlinear polarization rotation (NPR) is used to realize mode-locking without any dis...We report on a theoretical and experimental study of an all-normal-dispersion (ANDi) Yb-doped mode-locked fiber laser, in which nonlinear polarization rotation (NPR) is used to realize mode-locking without any dispersion compensation. Based on the coupled nonlinear Schr6dinger (CNLS) equation, a model simulating the mode-locked process of an all-normal-dispersion ring fiber laser is developed, which shows that the achievement of stable mode-locking depends on the alignment of the polarization controller (PC) along the fast-polarization axis of the fiber, the birefringence intensity, and the net cavity dispersion. According to the theoretical analysis, stable mode-locked pulses with pulse duration 300 ps and average output power 33.9 mW at repetition rate 36 MHz are obtained.展开更多
The transition state between the continuous wave region and the mode-locked region in a passively mode-locked erbium-doped fibre ring laser has been experimentally observed by utilizing the nonlinear polarization rota...The transition state between the continuous wave region and the mode-locked region in a passively mode-locked erbium-doped fibre ring laser has been experimentally observed by utilizing the nonlinear polarization rotation technique. When the pump power reaches the mode-locked threshold, the metastable pulse train with a tunable repetition rate is obtained in the transition from the continuous wave state to the passive mode-locked state via proper adjustment of the polarization controller. A simpie model has been established to explain the experimental observation.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 62072378)Xi’an Science and Technology Plan Project, China (Grant No. GXYD20.4)。
文摘A band-pass frequency selective surface(FSS) with polarization rotation property is proposed. The proposed polarization rotating FSS(PR-FSS) is a two-dimensional periodic structure, its unit cell is an antenna-filter-antenna(AFA) module,and the polarization directions of the upper and lower antennas in each AFA module are orthogonal to each other, so the PR-FSS can achieve frequency selection and 90 degrees polarization rotation at the same time. The numerical simulation demonstrate that the anticipated frequency selection and polarization rotation are realized by the PR-FSS in the frequency band from 8.84 GHz to 10.30 GHz with a relative bandwidth of 15.26%, and the maximum insertion loss in the pass band is only 0.17 d B. Finally, one effective experiment validation is carried out, a reasonable agreement is observed between the experimental and simulated results except for a slight deviation caused by fabrication error and measurement tolerance.
基金Project supported by the Ministry of Education of China(Grant Nos105036 and NCET-04-0116)
文摘Taking into account ultra-fast carrier dynamics, this paper models 640 Gbit/s wavelength conversion scheme based on nonlinear polarization rotation (NPR) in a single semiconductor optical amplifier (SOA) and investigates the performance of this kind of wavelength conversion scheme in detail. In this model, two carrier temperature equations are introduced to substitute two energy density equations, which reduce the complexity of calculation in comparison with the previous model. The temporary gain and phase shift dynamics induced by ultra-short optical pulses are numerically simulated and the simulated results are qualitatively in good agreement with reported experimental results. Simulated results show that non-inverted and inverted 640 Gbit/s wavelength conversions based on NPR are achieved with clear open eye diagrams. To further investigate the performance of the non-inverted wavelength conversion scheme, the dependence of output extinction ratio (ER) on some key parameters used in simulation is illustrated. Furthermore, simulated analyses show that high performance non-inverted wavelength conversion based on NPR can be achieved by using a red-shifted filtering scheme.
基金supported by the National Natural Science Foundation of China(Grant No.61077014)the National Basic Research Program of China(Grant No.2010CB327601)
文摘A theoretical model of the refractive index changes of the TE and TM modes in an electro-absorption modulator (EAM) is deduced. The photon absorption and refractive index changes are analyzed numerically. The influence of pump intensity on the phase difference between the TE and TM modes is studied. The polarization rotation effect is obtained in the EAM, and a novel all-optical fiber loop buffer is designed.
基金the Guangdong Major Project of Basic Research(Grant No.2020B0301030009)the National Key R&D Program of China(Grant No.2018YFB1801801)+4 种基金the National Natural Science Foundation of China(Grant Nos.61935013,61975133,11947017,and 12104318)the Natural Science Foundation of Guangdong Province(Grant No.2020A1515011185)the Science and Technology Innovation Commission of Shenzhen(Grant Nos.KQTD20170330110444030,JCYJ20180507182035270,and JCYJ20200109114018750)Shenzhen University(Grant No.2019075)China Postdoctoral Science Foundation(Grant No.2021T140470).
文摘Polarization rotation and vector field steering of electromagnetic wave are of great significance in modern optical applications.However,conventional polarization devices are bulky,monofunctional and lack of tunability,which pose great challenges to the miniaturized and multifunctional applications.Herein,we propose a meta-device that is capable of multi-state polarization rotation and vector field steering based on phase change metasurface.The supercell of the meta-device consists of four Ge2Sb2Te5(GST)elliptic cylinders located on a SiO2 substrate.By independently controlling the phase state(amorphous or crystalline)of each GST elliptic cylinder,the meta-device can rotate the polarization plane of the linearly polarized incident light to different angles that cover from 19.8°to 154.9°at a wavelength of 1550 nm.Furthermore,by merely altering the phase transition state of GST elliptic cylinders,we successfully demonstrated a vector field steering by generating optical vortices carrying orbital angular momentums(OAMs)with topological charges of 0,1 and–1,respectively.The proposed method provides a new platform for investigating dynamically tunable optical devices and has potential applications in many fields such as optical communications and information processing.
文摘A catadioptric lens structure,also known as pancake lens,has been widely used in virtual reality(VR)displays to reduce the formfactor.However,the utilization of a half mirror(HM)to fold the optical path thrice leads to a significant optical loss.The theoretical maximum optical efficiency is merely 25%.To transcend this optical efficiency constraint while retaining the foldable characteristic inherent to traditional pancake optics,in this paper,we propose a theoretically lossless folded optical system to replace the HM with a nonreciprocal polarization rotator.In our feasibility demonstration experiment,we used a commercial Faraday rotator(FR)and reflective polarizers to replace the lossy HM.The theoretically predicted 100%efficiency can be achieved approximately by using two high-extinction-ratio reflective polarizers.In addition,we evaluated the ghost images using a micro-OLED panel in our imaging system.Indeed,the ghost images can be suppressed to undetectable level if the optics are with antireflection coating.Our novel pancake optical system holds great potential for revolutionizing next-generation VR displays with lightweight,compact formfactor,and low power consumption.
基金Fundamental Research Funds for the Central Universities(2016YJS034)
文摘A mode-locked thulium-doped fiber laser(TDFL) based on nonlinear polarization rotation(NPR) with different net anomalous dispersion is demonstrated. When the cavity dispersion is-1.425 ps^2, the noise-like(NL) pulse with coherence spike width of 406 fs and pulse energy of 12.342 nJ is generated at a center wavelength of 2003.2 nm with 3 dB spectral bandwidth of 23.20 nm. In the experimental period of 400 min, the 3 dB spectral bandwidth variation, the output power fluctuation, and the central wavelength shift are less than 0.06 nm, 0.04 d B, and0.4 nm, respectively, indicating that the NPR-based TDFL operating in the NL regime holds good long-term stability.
基金supported by the National Basic Research Program of China(No.2006CB921203)the National Natural Science Foundation of China(No.11174327)+1 种基金the Foundation of Wuhan National Laboratory for Optoelectronics(No.P080002)the support of the Hundred Talent Program by the Chinese Academy of Sciences
文摘We report the experimental demonstration of an ultranarrow bandwidth atomic filter by optically induced polarization rotation in multilevel electromagnetically induced transparency systems in hot Rb vapor. With a coupling intensity of 2.3 W/cm^2, the filter shows a peak transmission of 33.2% and a bandwidth of 10 MHz. By altering the coupling frequency, a broad tuning range of several Doppler linewidths of the D1 line transitions of STRb atoms can be obtained. The presented atomic filter has useful features of ultranarrow bandwidth, and the operating frequency can be tuned resonance with the atomic transition. Such narrowband tunable atomic filter can be used as an efficient noise rejection tool in classical and quantum optical applications.
基金The project was supported by Open Fund of State Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), the National Natural Science Foundation of China (Grant Nos. 60978007, 61027007 and 61177067)
文摘A novel design of optical sampling system has been developed by using sum-frequency generation (SFG) in a periodically-poled lithium niobate (PPLN) waveguide and using passive mode-locked fiber laser pulses as optical sampling pulses. The system achieved high temporal resolution and high sensitivity using a 30 mm length PPLN with quasi phase match period of 19.3 μm and 151 fs sampling pulses which were generated by passive modelock fiber laser based on nonlinear polarization rotation (NPR). Clear eye-diagram of 10 Gbit/s non-return-to-zeros (NRZ) pseudorandom binary sequence (PRBS) optical signal were successfully reconstructed by this system.
基金National Natural Science Foundation of China(NSFC)(11274106,11474089)
文摘In this paper,we examine the tiny polarization rotation effect in total internal reflection due to the spin–orbit interaction of light.We find that the tiny polarization rotation rate will induce a geometric phase gradient,which can be regarded as the physical origin of photonic spin Hall effect.We demonstrate that the spin-dependent splitting in position space is related to the polarization rotation in momentum space,while the spin-dependent splitting in momentum space is attributed to the polarization rotation in position space.Furthermore,we introduce a quantum weak measurement to determine the tiny polarization rotation rate.The rotation rate in momentum space is obtained with 118 nm,which manifests itself as a spatial shift,and the rotation rate in position space is achieved with 38 μrad∕λ,which manifests itself as an angular shift.The investigation of the polarization rotation characteristics will provide insights into the photonic spin Hall effect and will enable us to better understand the spin–orbit interaction of light.
基金supported by the National Key R&D Program of China(No.2017YFE0123700)the National Natural Science Foundation of China(Nos.61925507 and 62075227)+1 种基金the Shanghai Rising-Star Program(No.21QA1410200)the Youth Innovation Promotion Association CAS(No.2020248).
文摘We demonstrate the simultaneous temporal contrast improvement and pulse compression of a Yb-doped femtosecond laser via nonlinear elliptical polarization rotation in a solid state multi-pass cell.The temporal contrast is improved to 109,while the pulse is shortened from 181 to 36 fs,corresponding to a compression factor of 5.The output beam features excellent beam quality with M^(2) values of 1.18×1.16.The total efficiency of the contrast enhancement system exceeds 50%.This technique will have wide applications in high temporal contrast ultra-intense femtosecond lasers.
基金supported by the National Key R&D Program of China(No.2017YFB0503100)the National Science Foundation of China(NSFC)(No.61227902)
文摘The measurement of an extremely small magneto-optical polarization rotation angle with high sensitivity is integral to many scientific and technological applications. In this Letter, we have presented a technique based on Faraday modulation combined with the optical differential method to measure an extremely small polari- zation rotation angle with high sensitivity. The theoretical and experimental results show that common mode noise is reduced appreciably and signal to noise ratio is enhanced. The effectiveness of this technique has been demonstrated by measuring the Verdet constant of terbium gallium garnet glass and measuring the small polari- zation rotation angle. A sensitivity of enhancement of one order of magnitude has been achieved using differ- ential detection based on Faraday modulation.
基金supported by the Start-up Research Foundation of Hainan University[grant no.KYQD(ZR)1816]the support from Ministry of Education,Singapore,through National University of Singapore(NUS)under the Academic Research Fund(grant no.R265-000-496-112).
文摘This paper presents multiple-modes Scanning Probe Microscopy(SPM)studies on characterize the correlation of resistance switching(RS)and polarization rotation(PR)in copper doped ZnO(ZnO:Cu)thin films.Firstly,the bipolar RS behavior is confirmed by conductive Atomic Force Microscopy(c-AFM).The PR with almost 180phase angle is confirmed by using the Piezoresponse Force Microscopy(PFM)on the same location.In addition,it elucidates that obvious PR behavior can be observed in the sample with increasing Cu concentration by combining Kelvin Probe Force Microscopy(KPFM).Furthermore,it is found that the region with downward polarization has low resistance state(LRS),whereas the region with upward polarization has high resistance state(HRS).Moreover,the Piezoresponse Force Spectroscopy(PFS)and Switching Spectroscopy PFM(SS-PFM)measurements further confirm that the existence of the built-in voltage,V_(built-in) is largest in the ZnO:Cu(8 at.%)film deposited at the oxygen partial pressure of 2×10^(-4) Torr.The schematic diagrams of energy band diagram with varied built-in field,Ebuilt-in,polarization directions and redistributed charges are presented to explain the correlation between RS and PR behavior.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11304093 and 11274114)the Hubei Provincial Natural Science Foundation,China(Grant No.2018CFB320)the Academic Discipline Project of Hubei Normal University,China(Grant Nos.2014F012 and 2014F013).
文摘Diffraction-free vectorial elliptic hollow beams(vEHBs)are generated by an optical system composed of a short elliptic hollow fiber(EHF)and an axicon.Each beam has a closed elliptic annular intensity profile and space-varying polarization states in its diffraction-free distance of more than 1 m.The generated beams have a counter-clockwise or clockwise periodically-rotated inhomogeneous polarization.And the spin angular momentum(SAM)of the vEHBs is 1ħor-1ħwhich is consistent with the type of dual-mode in the EHF and the periodic polarization rotations of the vEHBs.The vEHBs have potential applications in optically trapping and micromanipulating the micro-or nano-particles,quantum information transmission,and Bose-Einstein condensates,etc.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11274181,10974100,61203204,and 10674075)the Doctoral Scientific Fund Project of the Ministry of Education of China(Grant No.20120031110033)the Tianjin Key Program of Application Foundations and Future Technology Research Project,China(Grant No.10JCZDJC24300)
文摘A new polarization rotator based on the silica photonic crystal fiber is proposed. The proposed polarization rotator photonic crystal fiber (PR-PCF) possesses a triangle jigsaw-shape core region. The full-vector finite-element method is used to analyze the phenomenon of polarization conversion between the quasi-TE and quasi-TM modes. Numerical simulations show that the wavelengths of 1.31 μm and 1.55 μm are converted with a nearly 100% polarization conversion ratio with their matched coupling length and has a relatively strong realistic fabrication tolerance - 100 nm on the y axis and 50 nm on the x axis. The full vectorial finite difference beam propagation method is used to confirm the performance of the proposed PR-PCF.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.60990322,60990320,60801001,and 61101011)the Key Grant Project of Ministry of Education of China(Grant No.313029)+1 种基金the Ph.D.Program Foundation of Ministry of Education of China(Grant Nos.20100091110036 and 20120091110032)the Jiangsu Key Laboratory of Advanced Techniques for Manipulating Electromagnetic Waves,China
文摘A frequency selective polarization rotator that can rotate the polarization angle of an incident electromagnetic wave at the microwave frequency by 45 is presented. The polarization rotator is based on a two-dimensional periodic array of substrate integrated waveguide cavities, realizing the polarization rotation by coupling the input signal to the output wave through three metallic slots. Two layers of frequency selective surfaces are cascaded by substrate and form the polarization rotator. A vertical slot on the top layer is used to select the horizontal polarization from the incident wave, the vertical and the horizontal slots on the bottom layer are, respectively, used to obtain horizontally and vertically polarized outgoing waves. The two orthogonal outgoing waves are combined to result in the 45~ polarized wave. Both full wave simulation and experimental measurement are carried out, together validating the proposed method.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11474141and 11274149)the Program for Liaoning Excellent Talents in University,China(Grant No.LJQ2015040)+2 种基金the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry,China(Grant No.2014-1685)the Special Fund Based Research New Technology of Methanol Conversion and Coal Instead of Oilthe China Postdoctoral Science Foundation(Grant No.2014M550158)
文摘Quasi-classical trajectory calculations are performed to study the stereodynamics of the H(~2S) + NH(a^1?) →H_2(X^1Σ_g~+) + N(~2D) reaction based on the first excited state NH_2(1~2A') potential energy surface reported by Li et al.[Li Y Q and Varandas A J C 2010 J. Phys. Chem. A 114 9644] for the first time. We observe the changes of differential cross-sections at different collision energies and different initial reagent rotational excitations. The influence of collision energy on the k-k' distribution can be attributed to a purely impulsive effect. Initial reagent rotational excitation transforms the reaction mechanism from insertion to abstraction. The effect of initial reagent rotational excitations on k-k' distribution can be explained by the rotational excitation enlarging the rotational rate of reagent NH in the entrance channel to reduce the probability of collision between incidence H atom and H atom of target molecular. We also investigate the changes of vector correlations and find that the rotational angular momentum vector j' of the product H_2 is not only aligned, but also oriented along the y axis. The alignment parameter, the disposal of total angular momentum and the reaction mechanism are all analyzed carefully to explain the polarization behavior of the product rotational angular moment.
基金supported by the Key R&D Program of Zhejiang Province(No.2019C03065)。
文摘Silicon waveguides typically exhibit optical anisotropy,which leads to polarization correlation and single-polarization operations.This consequently creates a demand for polarization-control devices.This paper introduces a CMOS-compatible O-band reconfigurable TE/TM polarization rotator comprising two symmetrical polarization rotator-splitters and phase shifters.This configuration enables dynamic conversion of any linear polarization to its quadratic equivalent.Experimental results indicate that the reconfigurable polarization rotator exhibits an insertion loss of less than 1.5 dB.Furthermore,the bandwidth for a polarization extinction ratio beyond 15 dB exceeds 60 nm.
基金the National Natural Science Foundation of China(Grant No.6170031626)the Natural Science Foundation of Chongqing City,China(Grant Nos.cstc2018jcyjAX0585 and cstc2017zdzxX0011).
文摘We experimentally demonstrated a stable multi-wavelength bright-dark pulse pair in a mode-locked thulium-doped fiber laser(TDFL).The nonlinear polarization rotation(NPR)and nonlinear optical loop mirror(NOLM)were employed in a figure-eight cavity to allow for multi-wavelength mode-locking operation.By incorporating different lengths of high birefringence polarization-maintaining fiber(PMF),the fiber laser could operate stably in a multi-wavelength emission state.Compared with the absence of the PMF,the birefringence effect caused by PMF resulted in rich multi-wavelength optical spectra and better intensity symmetry and stability of the bright-dark pulse pair.
文摘We report on a theoretical and experimental study of an all-normal-dispersion (ANDi) Yb-doped mode-locked fiber laser, in which nonlinear polarization rotation (NPR) is used to realize mode-locking without any dispersion compensation. Based on the coupled nonlinear Schr6dinger (CNLS) equation, a model simulating the mode-locked process of an all-normal-dispersion ring fiber laser is developed, which shows that the achievement of stable mode-locking depends on the alignment of the polarization controller (PC) along the fast-polarization axis of the fiber, the birefringence intensity, and the net cavity dispersion. According to the theoretical analysis, stable mode-locked pulses with pulse duration 300 ps and average output power 33.9 mW at repetition rate 36 MHz are obtained.
基金Project supported by the National Natural Science Foundation of China(Grant No.11074078)the Specialized Research Fund for the Doctoral Program of Higher Education,China(Grant No.20094407110002)+1 种基金the Key Program for Scientific and Technological Innovations of Higher Education Institutes in Guangdong Province,China(Grant No.cxzd1011)the Foundation for Distinguished Young Talents in Higher Education of Guangdong,China(Grant No.C10183)
文摘The transition state between the continuous wave region and the mode-locked region in a passively mode-locked erbium-doped fibre ring laser has been experimentally observed by utilizing the nonlinear polarization rotation technique. When the pump power reaches the mode-locked threshold, the metastable pulse train with a tunable repetition rate is obtained in the transition from the continuous wave state to the passive mode-locked state via proper adjustment of the polarization controller. A simpie model has been established to explain the experimental observation.