The ability to simulate physical systems is essential for an understanding of their physical properties and advancing related technologies.However,simulating certain complex systems at scale,including many-body spin m...The ability to simulate physical systems is essential for an understanding of their physical properties and advancing related technologies.However,simulating certain complex systems at scale,including many-body spin models,is often a significant challenge for conventional computing approaches.Quantum simulators,employing controlled quantum systems that mimic the dynamics of a target system,can offer a more efficient approach.This work demonstrates the use of photonic circuits for quantum simulation of disordered spin systems,where quantum properties such as superposition and interference can be leveraged for a more efficient simulation.We fabricate and characterize a low-loss silicon-on-insulator chip with a buried aluminum mirror and a reconfigurable interferometer,which is employed in conjunction with two input photons to map the dynamics of a spin Hamiltonian with four-body interactions.Our results demonstrate several characteristics associated with the target system,such as spin-degenerate ground states and phase transitions,confirming the device's functionality as a quantum simulator of the spin system.展开更多
Since perovskite solar cells appeared in 2009, its simple preparation process, high photoelectric conversion efficiency and the characteristic of low cost in preparation process let it become the hot spot of both at-h...Since perovskite solar cells appeared in 2009, its simple preparation process, high photoelectric conversion efficiency and the characteristic of low cost in preparation process let it become the hot spot of both at-home and abroad. Owing to the constant efforts of scientists, the conversion efficiency of perovskite solar cells is more than 20% now. Perovskite solar cells are mainly composed of conductive glass, electron transport layer and hole transport layer, perovskite layer and electrode parts. This paper will briefly introduce the working principle and working pro- cess about the electron transport layer of perovskite solar cells. The paper focuses on aspects such as material types （e.g., inorganic electron transport materials, organic small molecule electron transport materials, surface modified electron transport materials and doped electron transport materials）, preparation technology of electron transport layer, the effects of electron transport layer on the photo- voltaic performance of the devices, and the electron transport layer in the future research.展开更多
Correction to:Rare Met.(2018)37(2):95–106 https://doi.org/10.1007/s12598-017-0951-4 In the original publication,the affiliation of Min-Hao Li was published incorrectly as below.
Entanglement distribution between distant parties is one of the most important and challenging tasks in quantum communication.Distribution of photonic entangled states using optical fiber links is a fundamental buildi...Entanglement distribution between distant parties is one of the most important and challenging tasks in quantum communication.Distribution of photonic entangled states using optical fiber links is a fundamental building block toward quantum networks.Among the different degrees of freedom,orbital angular momentum(OAM)is one of the most promising due to its natural capability to encode high dimensional quantum states.We experimentally demonstrate fiber distribution of hybrid polarization-vector vortex entangled photon pairs.To this end,we exploit a recently developed air-core fiber that supports OAM modes.High fidelity distribution of the entangled states is demonstrated by performing quantum state tomography in the polarization-OAM Hilbert space after fiber propagation and by violations of Bell inequalities and multipartite entanglement tests.The results open new scenarios for quantum applications where correlated complex states can be transmitted by exploiting the vectorial nature of light.展开更多
To achieve photon-pair generation scaling, we optimize the quality factor of microring resonators for efficient continuous-wave-pumped spontaneous four-wave mixing. Numerical studies indicate that a high intrinsic qua...To achieve photon-pair generation scaling, we optimize the quality factor of microring resonators for efficient continuous-wave-pumped spontaneous four-wave mixing. Numerical studies indicate that a high intrinsic quality factor makes high pair rate and pair brightness possible, in which the maximums take place under overcoupling and critical-coupling conditions, respectively. We fabricate six all-pass-type microring resonator samples on a silicon-on-insulator chip involving gap width as the only degree of freedom. The signal count rate, pair brightness,and coincidence rate of all the samples are characterized, which are then compared with the modified simulations by taking the detector saturation and nonlinear loss into account. Being experimentally validated for the first time to the best of our knowledge, this work explicitly demonstrates that reducing the round-trip loss in a ring cavity and designing the corresponding optimized gap width are more effective to generate high-rate or high-brightness photon pairs than the conventional strategy of simply increasing the quality factor.展开更多
The connection between Maxwell’s equations and neural networks opens unprecedented opportunities at the interface between photonics and deep learning.This feature issue highlights recent research progress at the inte...The connection between Maxwell’s equations and neural networks opens unprecedented opportunities at the interface between photonics and deep learning.This feature issue highlights recent research progress at the interdisciplinary field of photonics and deep learning and provides an opportunity for different communities to exchange their ideas from different perspectives.展开更多
An antireflection （AR） coating is fabricated by applying an optimal spin-coating method and a pH-modified SiO2 nanoparticle solution on a cover glass. Because the pH value of the solution will affect the aggregation...An antireflection （AR） coating is fabricated by applying an optimal spin-coating method and a pH-modified SiO2 nanoparticle solution on a cover glass. Because the pH value of the solution will affect the aggregation and dispersion of the SiO2 particles, the transmittance of the AR-treated cover glass will be enhanced under optimal fabricated conditions. The experimental results show that an AR coating fabricated by an SiO2 nano- particle solution of pH 11 enhances the transmittance approximately by 3% and 5% under normal and oblique incident conditions, respectively. Furthermore, the AR-treated cover glass exhibits hydrophobicity and shows a 65% enhancement at a contact angle to bare glass.展开更多
Diatoms are unicellular algae enclosed in intricate bio-silicified walls with repetitive nanostructures in a size range which makes them potentially relevant for a broad spectrum of industrial applications. How to opt...Diatoms are unicellular algae enclosed in intricate bio-silicified walls with repetitive nanostructures in a size range which makes them potentially relevant for a broad spectrum of industrial applications. How to optimize the nano-scale structures of the frustule for utilization of diatoms in nanotechnology is one of the technological challenges for these applications. Light is one of the most important abiotic factors for algal photosynthetic growth, and the frustule may play an important role in mediating light for these biological functions, as well as being central for its nano-technological applications. In this study we tested the influence of light quality on the nanostructure of the frustule of Coscinodiscus granii and compared this to growth rate response. The results showed that colored light （red, yellow, green and blue） at 300μmol photons m-2-s-1 resulted in a statistically significant change in nanostructure compared to white light. Green light at 100 μmol photon m-2.s-1 led to a significant decrease in mean frustule diameter and mean foramen diameter. Numerical simulations confirmed that the morphological changes obtained were sufficient to induce clear differences in the photonics properties of the frustule. The wavelength had no effect on the growth rate at high light intensity （300 μmol photons m-2.s-1）. However, at 100 μmol photons m-2.s-1, yellow, red-orange and green light resulted in significantly lower maximum growth rates than the other wavelengths. This response of the frustule structure to different light treatment indicates the possibility of a light-based frustule nanostructure manipulation method, which is simple and environmentally friendly.展开更多
The mechanism of strain-dependent luminescence is important for the rational design of pressure-sensing devices. The interband momentum-matrix element is the key quantity for understanding luminescent phenomena. We an...The mechanism of strain-dependent luminescence is important for the rational design of pressure-sensing devices. The interband momentum-matrix element is the key quantity for understanding luminescent phenomena. We analytically solved an infinite quantum well （IQW） model with strain, in the framework of the 6 × 6 k.p Hamiltonian for the valence states, to directly assess the interplay between the spin-orbit coupling and the strain-induced deformation potential for the interband momentum-matrix element. We numerically addressed problems of both the infinite and IQWs with piezoelectric fields to elucidate the effects of the piezoelectric potential and the deformation potential on the straindependent luminescence. The experimentally measured photoluminescence variation as a function of pressure can be qualitatively explained by the theoretical results.展开更多
Broadband(1.6–18 THz) terahertz time-domain spectroscopy(THz-TDS) and time-resolved terahertz spectroscopy(TRTS) were performed on a 54 μm thick chalcogenide glass(As_(30)Se_(30)Te_(40)) sample with a two-color lase...Broadband(1.6–18 THz) terahertz time-domain spectroscopy(THz-TDS) and time-resolved terahertz spectroscopy(TRTS) were performed on a 54 μm thick chalcogenide glass(As_(30)Se_(30)Te_(40)) sample with a two-color laser-induced air plasma THz system in transmission and reflection modes, respectively. Two absorption bands at 2–3 and 5–8 THz were observed. TRTS reveals an ultrafast relaxation process of the photoinduced carrier response, well described by a rate equation model with a finite concentration of mid-bandgap trap states for self-trapped excitons.The photoinduced conductivity can be well described by the Drude–Smith conductivity model with a carrier scattering time of 12–17 fs, and we observe significant carrier localization effects. A fast refractive index change was observed 100 fs before the conductivity reached its maximum, with 2 orders of magnitude larger amplitude than expected for the optically induced THz Kerr effect, indicating that free carriers are responsible for the transient index change.展开更多
Wavelength conversion based on degenerate four-wave mixing （FWM） was demonstrated and compared between silicon nanowire and microring resonator （MRR）. 15 dB enhancement of conversion efficiency （CE） with relativ...Wavelength conversion based on degenerate four-wave mixing （FWM） was demonstrated and compared between silicon nanowire and microring resonator （MRR）. 15 dB enhancement of conversion efficiency （CE） with relatively low input pump power （5roW） was achieved experimentally in an MRR. The impacts of bus waveguide length and propagation loss were theoretically analyzed under the effect of nonlinear loss.展开更多
In this paper, we proposed and experimentally demonstrated a route-asymmetrical light transmission scheme based on the thermal radiative effect, which means that forward and backward propagations of an optical device ...In this paper, we proposed and experimentally demonstrated a route-asymmetrical light transmission scheme based on the thermal radiative effect, which means that forward and backward propagations of an optical device have different transmittances provided they are not present simultaneously. Employing a fiber-chipfiber optomechanical system, our scheme has successfully achieved a broad operation bandwidth of at least 24 nm and an ultra-high route-asymmetrical transmission ratio （RATR） up to 63 dB. The route-asymmetrical device has been demonstrated effectively with not only the continuous-wave （CW） light but also 10 Gbit/s on-off-keying （OOK） digital signals. Above mentioned unique features can be mostly attributed to the significant characteristics of the thermal radiative effect, which could cause a fiber displacement up to tens of microns. The powerful and significant thermal radiative effect opens up a new opportunity and method for route-asymmetrical light transmission. Moreover, this research may have important applications in all-optical systems, such as the optical limiters and ultra-low loss switches.展开更多
Leveraging developments in microfabrication open new possibilities for optical manipulation.With the structural design freedom from three-dimensional printing capabilities of two-photon polymerization,we are starting ...Leveraging developments in microfabrication open new possibilities for optical manipulation.With the structural design freedom from three-dimensional printing capabilities of two-photon polymerization,we are starting to see the emergence of cleverly shaped‘light robots’or optically actuated micro-tools that closely resemble their macroscopic counterparts in function and sometimes even in form.In this work,we have fabricated a new type of light robot that is capable of loading and unloading cargo using photothermally induced convection currents within the body of the tool.We have demonstrated this using silica and polystyrene beads as cargo.The flow speeds of the cargo during loading and unloading are significantly larger than when using optical forces alone.This new type of light robot presents a mode of material transport that may have a significant impact on targeted drug delivery and nanofluidics injection.展开更多
Tunable optical delay lines are one of the key building blocks in optical communication and microwave systems.In this work, tunable optical delay lines based on integrated grating-assisted contradirectional couplers a...Tunable optical delay lines are one of the key building blocks in optical communication and microwave systems.In this work, tunable optical delay lines based on integrated grating-assisted contradirectional couplers are proposed and experimentally demonstrated. The device performance is comprehensively improved in terms of parameter optimization, apodization analysis, and electrode design. Tunable group delay lines of 50 ps at different wavelengths within the bandwidth of 12 nm are realized with a grating length of 1.8 mm. Under thermal tuning mode, the actual delay tuning range is around 20 ps at 7.2 V voltage. At last, a new scheme adopting an ultra-compact reflector for doubling group delay is proposed and verified, achieving a large group delay line of 400 ps and a large dispersion value up to 5.5 × 10~6 ps∕(nm · km) within bandwidth of 12 nm. Under thermal tuning mode, the actual delay tuning range is around 100 ps at 8 V voltage.展开更多
Silicon micro-ring resonators （MRRs） are compact and versatile devices whose periodic frequency response can be exploited for a wide range of applications. In this paper, we review our recent work on linear all-opti...Silicon micro-ring resonators （MRRs） are compact and versatile devices whose periodic frequency response can be exploited for a wide range of applications. In this paper, we review our recent work on linear all-optical signal processing applications using silicon MRRs as passive filters. We focus on applications such as modulation format conversion, differential phase-shift keying （DPSK） demodulation, modulation speed enhancement of directly modulated lasers （DMLs）, and monocycle pulse generation. The possibility to implement polarization diversity circuits, which reduce the polarization dependence of standard silicon MRRs, is illustrated on the particular example of DPSK demodulation.展开更多
The hybrid multiplexing technique reactivates optical interconnect as it offers multiple dimensions to dramatically enhance the data capacity of a single wavelength carrier.A straightforward method to realize hybrid m...The hybrid multiplexing technique reactivates optical interconnect as it offers multiple dimensions to dramatically enhance the data capacity of a single wavelength carrier.A straightforward method to realize hybrid multiplexing is to perform polarization multiplexing for mode-multiplexed signals,by utilizing a mode-transparent polarization beam splitter(MTPBS),which can process multiple modes simultaneously.However,present PBSs mainly work in the single-mode regime,and it is not easy to redesign the conventional PBS to accommodate multiple modes,due to the severe mode dispersion.Here,a novel MTPBS,which can tackle a group of modes simultancously,is proposed and demonstrated.As a demonstration,the MTPBS supporting a total channel number of 13 is experimentally achieved,with low insertion loss and low modal/polarization cross talk.This work provides a new insight to realize hybrid multiplexing and represents a solution for high-density and large-capacity photonic integration.展开更多
With unique possibilities for controlling light in nanoscale devices, graphene plasmonics has opened new perspectives to the nanophotonics community with potential applications in metamaterials, modulators, photodetec...With unique possibilities for controlling light in nanoscale devices, graphene plasmonics has opened new perspectives to the nanophotonics community with potential applications in metamaterials, modulators, photodetectors, and sensors. In this paper, we briefly review the recent exciting progress in graphene plasmonics. We begin with a general description of the optical properties of graphene, particularly focusing on the dispersion of graphene-plasmon polaritons. The dispersion relation of graphene-plasmon polaritons of spatially extended graphene is expressed in terms of the local re- sponse limit with an intraband contribution.／~Vith this theoretical foundation of graphene-plasmon polaritons, we then discuss recent exciting progress, paying specific attention to the following top- ics： excitation of graphene plasmon polaritons, electron-phonon interactions in graphene on polar substrates, and tunable graphene plasmonics with applications in modulators and sensors. Finally, we address some of the apparent challenges and promising perspectives of graphene plasmonics.展开更多
Encircling an exceptional point(EP) in a parity-time(PT) symmetric system has shown great potential for chiral optical devices,such as chiral mode switching for symmetric and antisymmetric modes.However,to our best kn...Encircling an exceptional point(EP) in a parity-time(PT) symmetric system has shown great potential for chiral optical devices,such as chiral mode switching for symmetric and antisymmetric modes.However,to our best knowledge,chiral switching for polarization states has never been reported,although chiral polarization manipulation has significant applications in imaging,sensing,communication,etc.Here,inspired by the anti-PT symmetry,we demonstrate,for the first time to our best knowledge,an on-chip chiral polarizer by constructing a polarization-coupled anti-PT symmetric system.The transmission axes of the chiral polarizer are different for forward and backward propagation.A polarization extinction ratio of over 10 dB is achieved for both propagating directions.Moreover,a telecommunication experiment is performed to demonstrate the potential applications in polarization encoding signals.It provides a novel functionality for encircling-an-EP parametric evolution and offers a new approach for on-chip chiral polarization manipulation.展开更多
Light scattering is a fundamental property that can be exploited to create essential devices such as particle analysers.The most common particle size analyser relies on measuring the angle-dependent diffracted light f...Light scattering is a fundamental property that can be exploited to create essential devices such as particle analysers.The most common particle size analyser relies on measuring the angle-dependent diffracted light from a sample illuminated by a laser beam.Compared to other non-light-based counterparts,such a laser diffraction scheme offers precision,but it does so at the expense of size,complexity and cost.In this paper,we introduce the concept of a new particle size analyser in a collimated beam configuration using a consumer electronic camera and machine learning.The key novelty is a small form factor angular spatial filter that allows for the collection of light scattered by the particles up to predefined discrete angles.The filter is combined with a light-emitting diode and a complementary metal-oxide-semiconductor image sensor array to acquire angularly resolved scattering images.From these images,a machine learning model predicts the volume median diameter of the particles.To validate the proposed device,glass beads with diameters ranging from 13 to 125μm were measured in suspension at several concentrations.We were able to correct for multiple scattering effects and predict the particle size with mean absolute percentage errors of 5.09% and 2.5% for the cases without and with concentration as an input parameter,respectively.When only spherical particles were analysed,the former error was significantly reduced(0.72%).Given that it is compact(on the order of ten cm)and built with low-cost consumer electronics,the newly designed particle size analyser has significant potential for use outside a standard laboratory,for example,in online and in-line industrial process monitoring.展开更多
基金supported by the Villum Fonden Young Investigator Project QUANPIC(Grant No.00025298)the Danish National Research Foundation Center of Excellence,SPOC(Grant No.DNRF123)。
文摘The ability to simulate physical systems is essential for an understanding of their physical properties and advancing related technologies.However,simulating certain complex systems at scale,including many-body spin models,is often a significant challenge for conventional computing approaches.Quantum simulators,employing controlled quantum systems that mimic the dynamics of a target system,can offer a more efficient approach.This work demonstrates the use of photonic circuits for quantum simulation of disordered spin systems,where quantum properties such as superposition and interference can be leveraged for a more efficient simulation.We fabricate and characterize a low-loss silicon-on-insulator chip with a buried aluminum mirror and a reconfigurable interferometer,which is employed in conjunction with two input photons to map the dynamics of a spin Hamiltonian with four-body interactions.Our results demonstrate several characteristics associated with the target system,such as spin-degenerate ground states and phase transitions,confirming the device's functionality as a quantum simulator of the spin system.
基金financially supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions(No.SZBF201437)A Funding of Jiangsu Innovation Program for Graduate Education(No.SJLX16_0429)
文摘Since perovskite solar cells appeared in 2009, its simple preparation process, high photoelectric conversion efficiency and the characteristic of low cost in preparation process let it become the hot spot of both at-home and abroad. Owing to the constant efforts of scientists, the conversion efficiency of perovskite solar cells is more than 20% now. Perovskite solar cells are mainly composed of conductive glass, electron transport layer and hole transport layer, perovskite layer and electrode parts. This paper will briefly introduce the working principle and working pro- cess about the electron transport layer of perovskite solar cells. The paper focuses on aspects such as material types （e.g., inorganic electron transport materials, organic small molecule electron transport materials, surface modified electron transport materials and doped electron transport materials）, preparation technology of electron transport layer, the effects of electron transport layer on the photo- voltaic performance of the devices, and the electron transport layer in the future research.
文摘Correction to:Rare Met.(2018)37(2):95–106 https://doi.org/10.1007/s12598-017-0951-4 In the original publication,the affiliation of Min-Hao Li was published incorrectly as below.
基金P.Kristensen from OFS-Fitel for the fiber fabrication,and D.Poderini for many advices on the software development.Funding Information:This work was supported by the Center of Excellence,SPOC-Silicon Photonics for Optical Communications(ref DNRF123)by the People Programme(Marie Curie Actions)of the European Union’s Seventh Framework Programme(FP7/2007-2013)under REA grant agreement no.609405(COFUNDPostdocDTU)+1 种基金and by the ERC-Advanced grant PHOSPhOR(Photonics of Spin-Orbit Optical PhenomenaGrant Agreement No.694683).G.C.acknowledges Becas Chile and Conicyt.
文摘Entanglement distribution between distant parties is one of the most important and challenging tasks in quantum communication.Distribution of photonic entangled states using optical fiber links is a fundamental building block toward quantum networks.Among the different degrees of freedom,orbital angular momentum(OAM)is one of the most promising due to its natural capability to encode high dimensional quantum states.We experimentally demonstrate fiber distribution of hybrid polarization-vector vortex entangled photon pairs.To this end,we exploit a recently developed air-core fiber that supports OAM modes.High fidelity distribution of the entangled states is demonstrated by performing quantum state tomography in the polarization-OAM Hilbert space after fiber propagation and by violations of Bell inequalities and multipartite entanglement tests.The results open new scenarios for quantum applications where correlated complex states can be transmitted by exploiting the vectorial nature of light.
基金National Natural Science Foundation of China(NSFC)(60907003)Natural Science Foundation of Hunan Province,China(13JJ3001)+2 种基金Program for New Century Excellent Talents in University(NCET),China(NCET-12-0142)Danmarks Grundforskningsfond(DNRF)(DNRF123)China Scholarship Council(CSC)
文摘To achieve photon-pair generation scaling, we optimize the quality factor of microring resonators for efficient continuous-wave-pumped spontaneous four-wave mixing. Numerical studies indicate that a high intrinsic quality factor makes high pair rate and pair brightness possible, in which the maximums take place under overcoupling and critical-coupling conditions, respectively. We fabricate six all-pass-type microring resonator samples on a silicon-on-insulator chip involving gap width as the only degree of freedom. The signal count rate, pair brightness,and coincidence rate of all the samples are characterized, which are then compared with the modified simulations by taking the detector saturation and nonlinear loss into account. Being experimentally validated for the first time to the best of our knowledge, this work explicitly demonstrates that reducing the round-trip loss in a ring cavity and designing the corresponding optimized gap width are more effective to generate high-rate or high-brightness photon pairs than the conventional strategy of simply increasing the quality factor.
文摘The connection between Maxwell’s equations and neural networks opens unprecedented opportunities at the interface between photonics and deep learning.This feature issue highlights recent research progress at the interdisciplinary field of photonics and deep learning and provides an opportunity for different communities to exchange their ideas from different perspectives.
基金financially supporting this research under Contract No. NSC 102-2221-E-155-076-MY3
文摘An antireflection （AR） coating is fabricated by applying an optimal spin-coating method and a pH-modified SiO2 nanoparticle solution on a cover glass. Because the pH value of the solution will affect the aggregation and dispersion of the SiO2 particles, the transmittance of the AR-treated cover glass will be enhanced under optimal fabricated conditions. The experimental results show that an AR coating fabricated by an SiO2 nano- particle solution of pH 11 enhances the transmittance approximately by 3% and 5% under normal and oblique incident conditions, respectively. Furthermore, the AR-treated cover glass exhibits hydrophobicity and shows a 65% enhancement at a contact angle to bare glass.
文摘Diatoms are unicellular algae enclosed in intricate bio-silicified walls with repetitive nanostructures in a size range which makes them potentially relevant for a broad spectrum of industrial applications. How to optimize the nano-scale structures of the frustule for utilization of diatoms in nanotechnology is one of the technological challenges for these applications. Light is one of the most important abiotic factors for algal photosynthetic growth, and the frustule may play an important role in mediating light for these biological functions, as well as being central for its nano-technological applications. In this study we tested the influence of light quality on the nanostructure of the frustule of Coscinodiscus granii and compared this to growth rate response. The results showed that colored light （red, yellow, green and blue） at 300μmol photons m-2-s-1 resulted in a statistically significant change in nanostructure compared to white light. Green light at 100 μmol photon m-2.s-1 led to a significant decrease in mean frustule diameter and mean foramen diameter. Numerical simulations confirmed that the morphological changes obtained were sufficient to induce clear differences in the photonics properties of the frustule. The wavelength had no effect on the growth rate at high light intensity （300 μmol photons m-2.s-1）. However, at 100 μmol photons m-2.s-1, yellow, red-orange and green light resulted in significantly lower maximum growth rates than the other wavelengths. This response of the frustule structure to different light treatment indicates the possibility of a light-based frustule nanostructure manipulation method, which is simple and environmentally friendly.
基金Acknowledgements This work was supported by National Natural Science Foundation of China （Nos. 51472056 and 51402064）, the ＂thousands talents＂ program for pioneer researcher and his innovation team, China, the Recruitment Program of Global Youth Experts, China and Youth Innovation Promotion Assodation of Chinese Academy of Sciences （No. 2015387）. M. W. acknowledges financial support from the Chinese Academy of Sciences and the Beijing Institute for Nanoenergy and Nanosystems.
文摘The mechanism of strain-dependent luminescence is important for the rational design of pressure-sensing devices. The interband momentum-matrix element is the key quantity for understanding luminescent phenomena. We analytically solved an infinite quantum well （IQW） model with strain, in the framework of the 6 × 6 k.p Hamiltonian for the valence states, to directly assess the interplay between the spin-orbit coupling and the strain-induced deformation potential for the interband momentum-matrix element. We numerically addressed problems of both the infinite and IQWs with piezoelectric fields to elucidate the effects of the piezoelectric potential and the deformation potential on the straindependent luminescence. The experimentally measured photoluminescence variation as a function of pressure can be qualitatively explained by the theoretical results.
基金financial support from the Danish Research Council for Independent Research (FNU Project THz-BREW)
文摘Broadband(1.6–18 THz) terahertz time-domain spectroscopy(THz-TDS) and time-resolved terahertz spectroscopy(TRTS) were performed on a 54 μm thick chalcogenide glass(As_(30)Se_(30)Te_(40)) sample with a two-color laser-induced air plasma THz system in transmission and reflection modes, respectively. Two absorption bands at 2–3 and 5–8 THz were observed. TRTS reveals an ultrafast relaxation process of the photoinduced carrier response, well described by a rate equation model with a finite concentration of mid-bandgap trap states for self-trapped excitons.The photoinduced conductivity can be well described by the Drude–Smith conductivity model with a carrier scattering time of 12–17 fs, and we observe significant carrier localization effects. A fast refractive index change was observed 100 fs before the conductivity reached its maximum, with 2 orders of magnitude larger amplitude than expected for the optically induced THz Kerr effect, indicating that free carriers are responsible for the transient index change.
文摘Wavelength conversion based on degenerate four-wave mixing （FWM） was demonstrated and compared between silicon nanowire and microring resonator （MRR）. 15 dB enhancement of conversion efficiency （CE） with relatively low input pump power （5roW） was achieved experimentally in an MRR. The impacts of bus waveguide length and propagation loss were theoretically analyzed under the effect of nonlinear loss.
基金Acknowledgements This work was partially supported by the National Basic Research Program of China （No. 2011CB301704）, the Program for New Century Excellent Talents in Ministry of Education of China （No. NCET-11-0168）, a Foundation for the Author of National Excellent Doctoral Dissertation of China （No. 201139）, the National Natural Science Foundation of China （Grant Nos. 11174096 and 61475052）, and the Opened Fund of the State Key Laboratory on Advanced Optical Communication System and Network （No. 2015GZKF03004）.
文摘In this paper, we proposed and experimentally demonstrated a route-asymmetrical light transmission scheme based on the thermal radiative effect, which means that forward and backward propagations of an optical device have different transmittances provided they are not present simultaneously. Employing a fiber-chipfiber optomechanical system, our scheme has successfully achieved a broad operation bandwidth of at least 24 nm and an ultra-high route-asymmetrical transmission ratio （RATR） up to 63 dB. The route-asymmetrical device has been demonstrated effectively with not only the continuous-wave （CW） light but also 10 Gbit/s on-off-keying （OOK） digital signals. Above mentioned unique features can be mostly attributed to the significant characteristics of the thermal radiative effect, which could cause a fiber displacement up to tens of microns. The powerful and significant thermal radiative effect opens up a new opportunity and method for route-asymmetrical light transmission. Moreover, this research may have important applications in all-optical systems, such as the optical limiters and ultra-low loss switches.
基金supported by the Enhanced Spatial Light Control in Advanced Optical Fibres(e-space)project,financed by Innovation Fund Denmark(Grant No.0603-00514B).
文摘Leveraging developments in microfabrication open new possibilities for optical manipulation.With the structural design freedom from three-dimensional printing capabilities of two-photon polymerization,we are starting to see the emergence of cleverly shaped‘light robots’or optically actuated micro-tools that closely resemble their macroscopic counterparts in function and sometimes even in form.In this work,we have fabricated a new type of light robot that is capable of loading and unloading cargo using photothermally induced convection currents within the body of the tool.We have demonstrated this using silica and polystyrene beads as cargo.The flow speeds of the cargo during loading and unloading are significantly larger than when using optical forces alone.This new type of light robot presents a mode of material transport that may have a significant impact on targeted drug delivery and nanofluidics injection.
基金National Natural Science Foundation of China(NSFC)(61475052,61622502)Fundamental Research Funds for the Central Universities(2017KFXKJC001)
文摘Tunable optical delay lines are one of the key building blocks in optical communication and microwave systems.In this work, tunable optical delay lines based on integrated grating-assisted contradirectional couplers are proposed and experimentally demonstrated. The device performance is comprehensively improved in terms of parameter optimization, apodization analysis, and electrode design. Tunable group delay lines of 50 ps at different wavelengths within the bandwidth of 12 nm are realized with a grating length of 1.8 mm. Under thermal tuning mode, the actual delay tuning range is around 20 ps at 7.2 V voltage. At last, a new scheme adopting an ultra-compact reflector for doubling group delay is proposed and verified, achieving a large group delay line of 400 ps and a large dispersion value up to 5.5 × 10~6 ps∕(nm · km) within bandwidth of 12 nm. Under thermal tuning mode, the actual delay tuning range is around 100 ps at 8 V voltage.
文摘Silicon micro-ring resonators （MRRs） are compact and versatile devices whose periodic frequency response can be exploited for a wide range of applications. In this paper, we review our recent work on linear all-optical signal processing applications using silicon MRRs as passive filters. We focus on applications such as modulation format conversion, differential phase-shift keying （DPSK） demodulation, modulation speed enhancement of directly modulated lasers （DMLs）, and monocycle pulse generation. The possibility to implement polarization diversity circuits, which reduce the polarization dependence of standard silicon MRRs, is illustrated on the particular example of DPSK demodulation.
基金National Natural Science Foundation of China(61911530161,61922034)Program for HUST Academic Frontier Youth Team(2018QYTD08).
文摘The hybrid multiplexing technique reactivates optical interconnect as it offers multiple dimensions to dramatically enhance the data capacity of a single wavelength carrier.A straightforward method to realize hybrid multiplexing is to perform polarization multiplexing for mode-multiplexed signals,by utilizing a mode-transparent polarization beam splitter(MTPBS),which can process multiple modes simultaneously.However,present PBSs mainly work in the single-mode regime,and it is not easy to redesign the conventional PBS to accommodate multiple modes,due to the severe mode dispersion.Here,a novel MTPBS,which can tackle a group of modes simultancously,is proposed and demonstrated.As a demonstration,the MTPBS supporting a total channel number of 13 is experimentally achieved,with low insertion loss and low modal/polarization cross talk.This work provides a new insight to realize hybrid multiplexing and represents a solution for high-density and large-capacity photonic integration.
文摘With unique possibilities for controlling light in nanoscale devices, graphene plasmonics has opened new perspectives to the nanophotonics community with potential applications in metamaterials, modulators, photodetectors, and sensors. In this paper, we briefly review the recent exciting progress in graphene plasmonics. We begin with a general description of the optical properties of graphene, particularly focusing on the dispersion of graphene-plasmon polaritons. The dispersion relation of graphene-plasmon polaritons of spatially extended graphene is expressed in terms of the local re- sponse limit with an intraband contribution.／~Vith this theoretical foundation of graphene-plasmon polaritons, we then discuss recent exciting progress, paying specific attention to the following top- ics： excitation of graphene plasmon polaritons, electron-phonon interactions in graphene on polar substrates, and tunable graphene plasmonics with applications in modulators and sensors. Finally, we address some of the apparent challenges and promising perspectives of graphene plasmonics.
基金National Natural Science Foundation of China(61805090, 62075075)National Key Research and Development Project of China (2018YFB2201901)。
文摘Encircling an exceptional point(EP) in a parity-time(PT) symmetric system has shown great potential for chiral optical devices,such as chiral mode switching for symmetric and antisymmetric modes.However,to our best knowledge,chiral switching for polarization states has never been reported,although chiral polarization manipulation has significant applications in imaging,sensing,communication,etc.Here,inspired by the anti-PT symmetry,we demonstrate,for the first time to our best knowledge,an on-chip chiral polarizer by constructing a polarization-coupled anti-PT symmetric system.The transmission axes of the chiral polarizer are different for forward and backward propagation.A polarization extinction ratio of over 10 dB is achieved for both propagating directions.Moreover,a telecommunication experiment is performed to demonstrate the potential applications in polarization encoding signals.It provides a novel functionality for encircling-an-EP parametric evolution and offers a new approach for on-chip chiral polarization manipulation.
基金funded by the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No.637232(ProPAT project)financial support from the Spanish Ministry of Economy and Competitiveness through the‘Severo Ochoa’Programme for Centres of Excellence in R&D(SEV-2015-0522)+2 种基金from Fundacio Privada Cellex,and from Generalitat de Catalunya through the CERCA programme,from AGAUR 2017 SGR 1634financial support from the Spanish Ministry of Economy and Competitiveness through the project OPTO-SCREEN(TEC2016-75080-R)funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 665884.
文摘Light scattering is a fundamental property that can be exploited to create essential devices such as particle analysers.The most common particle size analyser relies on measuring the angle-dependent diffracted light from a sample illuminated by a laser beam.Compared to other non-light-based counterparts,such a laser diffraction scheme offers precision,but it does so at the expense of size,complexity and cost.In this paper,we introduce the concept of a new particle size analyser in a collimated beam configuration using a consumer electronic camera and machine learning.The key novelty is a small form factor angular spatial filter that allows for the collection of light scattered by the particles up to predefined discrete angles.The filter is combined with a light-emitting diode and a complementary metal-oxide-semiconductor image sensor array to acquire angularly resolved scattering images.From these images,a machine learning model predicts the volume median diameter of the particles.To validate the proposed device,glass beads with diameters ranging from 13 to 125μm were measured in suspension at several concentrations.We were able to correct for multiple scattering effects and predict the particle size with mean absolute percentage errors of 5.09% and 2.5% for the cases without and with concentration as an input parameter,respectively.When only spherical particles were analysed,the former error was significantly reduced(0.72%).Given that it is compact(on the order of ten cm)and built with low-cost consumer electronics,the newly designed particle size analyser has significant potential for use outside a standard laboratory,for example,in online and in-line industrial process monitoring.
