We investigate the effect of disorder and mechanical deformation on a two-dimensional photonic crystal waveguide. The dispersion characteristics and transmittance of the waveguide are studied using the finite element ...We investigate the effect of disorder and mechanical deformation on a two-dimensional photonic crystal waveguide. The dispersion characteristics and transmittance of the waveguide are studied using the finite element method. Results show that the geometric change of the dielectric material perpendicular to the light propagation direction has a larger influence on the waveguide characteristics than that parallel to the light propagation direction. Mechanical deformation has an obvious influence on the performance of the waveguide. In particular, longitudinal deformed structure exhibits distinct optical characteristics from the ideal one. Studies on this work will provide useful guideline to the fabrication and practical applications based on photonic crystal waveguides.展开更多
An electrically driven, single-longitudinal-mode GaAs based photonic crystal (PC) ridge waveguide (RWG) laser emitting at around 850 nm is demonstrated. The single-longitudinal-mode lasing characteristic is achieved b...An electrically driven, single-longitudinal-mode GaAs based photonic crystal (PC) ridge waveguide (RWG) laser emitting at around 850 nm is demonstrated. The single-longitudinal-mode lasing characteristic is achieved by introducing the PC to the RWG laser. The triangle PC is etched on both sides of the ridge by photolithography and inductive coupled plasma (ICP) etching. The lasing spectra of the RWG lasers with and without the PC are studied, and the result shows that the PC purifies the longitudinal mode. The power per facet versus current and current-voltage characteristics have also been studied and compared.展开更多
This paper studies the propagating characteristics of the electromagnetic waves through the coupled-resonator optical waveguides based on the two-dimensional square-lattice photonic crystals by the finite-difference t...This paper studies the propagating characteristics of the electromagnetic waves through the coupled-resonator optical waveguides based on the two-dimensional square-lattice photonic crystals by the finite-difference time-domain method.When the traditional circular rods adjacent to the centre of the cavities are replaced by the oval rods,the simulated results show that the waveguide mode region can be adjusted only by the alteration of the oval rods' obliquity.When the obliquity of the oval rods around one cavity is different from the obliquity of that around the adjacent cavities,the group velocities of the waveguide modes can be greatly reduced and the information of different frequencies can be shared and chosen at the same time by the waveguide branches with different structures.If the obliquities of the oval rods around two adjacent cavities are equal and they alternate between two values,the group velocities can be further reduced and a maximum value of 0.0008c(c is the light velocity in vacuum) can be acquired.展开更多
On the basis of two-dimensional amorphous photonic materials,we have designed a novel waveguide by inserting thinner cylindrical inclusions in the centre of basic hexagonal units of the amorphous structure along a giv...On the basis of two-dimensional amorphous photonic materials,we have designed a novel waveguide by inserting thinner cylindrical inclusions in the centre of basic hexagonal units of the amorphous structure along a given path.This waveguide in amorphous structure is similar to the coupled resonator optical waveguides in periodic photonic crystals.The transmission of this waveguide for S-polarized waves is investigated by a multiple-scattering method.Compared with the conventional waveguide by removing a line of cells from amorphous photonic materials,the guiding properties of this waveguide,including the transmissivity and bandwidth,are improved significantly.Then we study the effect of various types of positional disorder on the functionality of this device.Our results show that the waveguide performance is quite sensitive to the disorder located on the boundary layer of the waveguide,but robust against the disorder in the other area in amorphous structure except the waveguide border.This disorder effect in amorphous photonic materials is similar to the case in periodic photonic crystals.展开更多
Based on the present coupled mode theory of the photonic crystal resonator array in this paper,we propose a novel side-coupled waveguide to achieve highly efficient coupling of photonic crystal devices.It is found tha...Based on the present coupled mode theory of the photonic crystal resonator array in this paper,we propose a novel side-coupled waveguide to achieve highly efficient coupling of photonic crystal devices.It is found that the coupling efficiency is sensitive to the interval,the total number and the quality factor of the resonator.Considering the coupling efficiency and the coupling region,we select five resonators with an interval of six lattice periods.By optimizing the structure parameters of the waveguide and resonator,the quality factors of the resonator can be modulated and the coupling efficiency of the side-coupled waveguide reaches 95.47% in theory.Compared with other coupling methods,the side-coupled waveguide can realize efficient coupling with a compact structure,a high level of integration and a low degree of operational difficulties.展开更多
Transmission spectra of triangular lattice photonic crystals milled in the top surface of an annealed protonexchange waveguide are numerically simulated.The effects of the finite depth,conical shape,trapezoidal shape ...Transmission spectra of triangular lattice photonic crystals milled in the top surface of an annealed protonexchange waveguide are numerically simulated.The effects of the finite depth,conical shape,trapezoidal shape and hybrid shape of holes are theoretically analyzed.Due to the difficulty of milling high aspect-ratio cylindrical holes in lithium niobate(LiNbO_3),a compromised solution is proposed to improve the overlap between shallow holes and the waveguide mode,and useful transmission spectra with strong contrast and sharp band edges are achieved.展开更多
With the method of replacing the surface layer of photonic crystal with tubes, a novel photonic crystal composite structure used as a tunable surface mode waveguide is designed. The tubes support tunable surface state...With the method of replacing the surface layer of photonic crystal with tubes, a novel photonic crystal composite structure used as a tunable surface mode waveguide is designed. The tubes support tunable surface states. The tunable propagation capabilities of the structure are investigated by using the finite-difference time-domain. Simulation results show that the beam transmission distributions of the composite structure are sensitive to the frequency range of incident light and the surface morphology which can be modified by filling the tubes with different organic liquids. By adjusting the filler in tubes, the T-shaped, Y-shaped, and L-shaped propagations can be realized. The property can be applied to the tunable surface mode waveguide. Compared with a traditional single function photonic crystal waveguide, our designed structure not only has a small size, but also is a tunable device.展开更多
Recently, Zhang et al.(Chin. Phys. B 26 024208(2017)) investigated the band gap structures and semi-Dirac point of two-dimensional function photonic crystals, and the equations for the plane wave expansion method were...Recently, Zhang et al.(Chin. Phys. B 26 024208(2017)) investigated the band gap structures and semi-Dirac point of two-dimensional function photonic crystals, and the equations for the plane wave expansion method were induced to obtain the band structures. That report shows the band diagrams with the effects of function coefficient k and medium column r_a under TE and TM waves. The proposed results look correct at first glance, but the authors made some mistakes in their report. Thus, the calculated results in their paper are incorrect. According to our calculations, the errors in their report are corrected, and the correct band structures also are presented in this paper.展开更多
This paper reports that a two-dimensional single-defect photonic crystal waveguide in the Γ -K direction with triangular lattice on a silicon-on-insulator substrate is fabricated by the combination of electron beam l...This paper reports that a two-dimensional single-defect photonic crystal waveguide in the Γ -K direction with triangular lattice on a silicon-on-insulator substrate is fabricated by the combination of electron beam lithography and inductively coupled plasma etching. A ministop band (MSB) is observed by the measurement of transmission characteristics. It results from the coupling between the two modes with the same symmetry, which is analysed from the stimulated band diagram by the effective index and the two-dimensional plane wave expansion methods. The parameter working on the MSB is the ratio of the radius of air holes to the lattice constant, r/a. It is obtained that the critical r/a value determining the occurrence or disappearance of MSB is 0.36. When r/a is larger than or equal to 0.36, the MSB occurs. However, when r/a is smaller than 0.36, the MSB disappears.展开更多
In this paper, an optical waveguide junction is introduced to reduce crosstalk based on a hexagonal structure of photonic crystals for TE modes. The wavelength is 1330 nm which is an important wavelength for optical f...In this paper, an optical waveguide junction is introduced to reduce crosstalk based on a hexagonal structure of photonic crystals for TE modes. The wavelength is 1330 nm which is an important wavelength for optical fiber data transmission. Simulation results show that the proposed design exhibits a reduction of -50 dB in crosstalk. It translates to a considerable isolation improvement between two crossover waveguides. FDTD method is used to obtain the transmission coefficient.展开更多
GaP terahertz (THz) two-dimensional (2D) photonic crystal (PC) waveguides with line defects were fabricated using inductively-coupled plasma reactive-ion etching (ICP-RIE) in Ar/Cl2 gas chemistries. THz-wave generatio...GaP terahertz (THz) two-dimensional (2D) photonic crystal (PC) waveguides with line defects were fabricated using inductively-coupled plasma reactive-ion etching (ICP-RIE) in Ar/Cl2 gas chemistries. THz-wave generation from the fabricated PC waveguides was demonstrated under collinear phase-matched difference-frequency generation (DFG), using Cr:Forsterite (Cr:F) lasers as the incident source. We compared the THz-wave output characteristics of the PC waveguides with that of GaP planar waveguides. The collinear phase-matching conditions in the DFG process were satisfied for 300- and 500-μm-wide PC waveguide structures at 0.7 and 0.6 THz, respectively. The additional output peaks that appeared near the edge of the photonic band gap, around 0.5 THz, were attributed to the guiding modes in the PC waveguide;no such peaks appeared in the non-patterned ridge waveguides. These experimental results suggest that the phonon-polariton confinement in THz-PC waveguides based on the GaP crystal could be used to enhance the nonlinear optical effect for THz-wave generation.展开更多
Generation of hyperentangled photon pairs is investigated based on the lithium niobate straight waveguide.We propose to use the nonlinear optical process of spontaneous parametric down-conversion(SPDC)and a well-desig...Generation of hyperentangled photon pairs is investigated based on the lithium niobate straight waveguide.We propose to use the nonlinear optical process of spontaneous parametric down-conversion(SPDC)and a well-designed lithium niobate waveguide structure to generate a hyperentangled(in the polarization dimension and the energy-time dimension)two-photon state.By performing numerical simulations of the waveguide structure and calculating the possible polarization states,joint spectral amplitudes(JSA),and joint temporal amplitudes(JTA)of the generated photon pair,we show that the generated photon pair is indeed hyperentangled in both the polarization dimension and the energy-time dimension.展开更多
In this paper, we have designed and simulated all-optical tristate Pauli X, Y and Z gates using 2D photonic crystal. Simple line and point defects have been used to design the structure. The performance of the structu...In this paper, we have designed and simulated all-optical tristate Pauli X, Y and Z gates using 2D photonic crystal. Simple line and point defects have been used to design the structure. The performance of the structure has been analyzed and investigated by plane wave expansion(PWE) and finite difference time domain(FDTD) methods. Different performance parameters, namely contrast ratio(CR), rise time, fall time, delay time, response time and bit rate, have been calculated. The main advantage of the proposed design is that all the Pauli gates have been realized from a single structure. Due to compact size, fast response time, good CR and high bit rate, the proposed structure can be highly useful for optical computing, data processing and optical integrated circuits.展开更多
Optical waveguides are far more than mere connecting elements in integrated optical systems and circuits.Benefiting from their high optical confinement and miniaturized footprints,waveguide structures established base...Optical waveguides are far more than mere connecting elements in integrated optical systems and circuits.Benefiting from their high optical confinement and miniaturized footprints,waveguide structures established based on crystalline materials,particularly,are opening exciting possibilities and opportunities in photonic chips by facilitating their on-chip integration with different functionalities and highly compact photonic circuits.Femtosecond-laser-direct writing(FsLDW),as a true three-dimensional(3D)micromachining and microfabrication technology,allows rapid prototyping of on-demand waveguide geometries inside transparent materials via localized material modification.The success of FsLDW lies not only in its unsurpassed aptitude for realizing 3D devices but also in its remarkable material-independence that enables cross-platform solutions.This review emphasizes FsLDW fabrication of waveguide structures with 3D layouts in dielectric crystals.Their functionalities as passive and active photonic devices are also demonstrated and discussed.展开更多
This paper presents four rings square, circular, and hexagonal photonic crystal fiber (PCF) geometry for analyzing different optical properties in a wavelength ranging from 800 nm to 1600 nm. These three types of geom...This paper presents four rings square, circular, and hexagonal photonic crystal fiber (PCF) geometry for analyzing different optical properties in a wavelength ranging from 800 nm to 1600 nm. These three types of geometry have been used for analyzing Effective area, Propagation constant, Confinement loss and Waveguide dispersion. Silica glass is chosen as background material and the cladding region is made of four air hole layers. COMSOL Multiphysics (v.5) software is used to simulate these proposed PCF geometries. From the numerical analysis, it is found that the effective area is small for hexagonal PCF geometry and large for square PCF geometry (11.827 μm2, 10.588 μm2 and 9.405 μm2 for square, circular, and hexagonal PCF geometry respectively). From the analysis, the Confinement loss is approximately zero at wavelength ranges from 800 nm to 1250 nm and approximately zero waveguide dispersion is achieved from 900 nm to 1500 nm for all the three PCF structures. Again, negative dispersion approximately −30.354 ps/(nm⋅km) is achieved for circular PCF structure at the wavelength of 900 nm.展开更多
Two-dimensional metallic photonic crystal slabs with square lattice are proposed to be used for the design of waveguide bandpass filters operating in millimeter to terahertz region.Filter characteristics are studied w...Two-dimensional metallic photonic crystal slabs with square lattice are proposed to be used for the design of waveguide bandpass filters operating in millimeter to terahertz region.Filter characteristics are studied when rod radii and lattice constants are changed.Based on the frequency scaling technique,a series of higher frequency filters has been designed.By using laser drilling and welding processing techniques,a compact waveguide filter embedded in an EIA-WR10 waveguide with central frequency 145.5 GHz and3-dB bandwidth of 5.26 GHz is fabricated and measured.The measurement data agree well with the simulation prediction.展开更多
The light propagation characteristics through the annular coupled-resonator cavity waveguides are systematically analyzed by the finite-difference time-domain (FDTD) method. It is found that this kind of waveguide has...The light propagation characteristics through the annular coupled-resonator cavity waveguides are systematically analyzed by the finite-difference time-domain (FDTD) method. It is found that this kind of waveguide has more minbands owing to the increasing of the cavity’s size, compared with the traditional line-typed coupled-resonator waveguide. The group velocity of light propagation can be reduced for a further degree when the adjacent annular cavities are interlaced in the perpendicular direction, and a group velocity about 0.00067c (c is the light speed in vacuum) can be obtained.展开更多
Quantum light sources serve as one of the key elements in quantum photonic technologies. Such sources made from semiconductor material, e.g., quantum dots (QDs), are particularly appealing because of their great poten...Quantum light sources serve as one of the key elements in quantum photonic technologies. Such sources made from semiconductor material, e.g., quantum dots (QDs), are particularly appealing because of their great potential of scalability enabled by the modern planar nanofabrication technologies. So far, non-classic light sources based on semiconductor QDs are currently outperforming their counterparts using nonlinear optical process, for instance, parametric down conversion and four-wave mixing. To fully exploring the potential of semiconductor QDs, it is highly desirable to integrate QDs with a variety of photonic nanostructures for better device performance due to the improved light-matter interaction. Among different designs, the photonic nanostructures exhibiting broad operation spectral range is particularly interesting to overcome the QD spectral inhomogeneity and exciton fine structure splitting for the generations of single-photon and entangled photon pair respectively. In this review, we focus on recent progress on high-performance semiconductor quantum light sources that is achieved by integrating single QDs with a variety of broadband photonic nanostructures i.e. waveguide, lens and low-Q cavity.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 60908028, 60971068, 10979065, and 61275201)the Fundamental Research Funds for the Central Universities of China (Grant Nos. 2011RC0402 and 2012RC0402)the Program for New Century Excellent Talents in University of China (Grant No. NCET-10-0261)
文摘We investigate the effect of disorder and mechanical deformation on a two-dimensional photonic crystal waveguide. The dispersion characteristics and transmittance of the waveguide are studied using the finite element method. Results show that the geometric change of the dielectric material perpendicular to the light propagation direction has a larger influence on the waveguide characteristics than that parallel to the light propagation direction. Mechanical deformation has an obvious influence on the performance of the waveguide. In particular, longitudinal deformed structure exhibits distinct optical characteristics from the ideal one. Studies on this work will provide useful guideline to the fabrication and practical applications based on photonic crystal waveguides.
基金Project supported by the National Natural Science Foundation of China (Grant No. 91121019)the National Basic Research Program of China (Grant No. 2013CB632105)
文摘An electrically driven, single-longitudinal-mode GaAs based photonic crystal (PC) ridge waveguide (RWG) laser emitting at around 850 nm is demonstrated. The single-longitudinal-mode lasing characteristic is achieved by introducing the PC to the RWG laser. The triangle PC is etched on both sides of the ridge by photolithography and inductive coupled plasma (ICP) etching. The lasing spectra of the RWG lasers with and without the PC are studied, and the result shows that the PC purifies the longitudinal mode. The power per facet versus current and current-voltage characteristics have also been studied and compared.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10904176 and 11004169)the Research Foundation of the State Ethnic Affairs Commission of People’s Republic of China (Grant Nos. 10ZY05 and 09ZY012)the "985 Project" and "211 Project" of the Ministry of Education of China
文摘This paper studies the propagating characteristics of the electromagnetic waves through the coupled-resonator optical waveguides based on the two-dimensional square-lattice photonic crystals by the finite-difference time-domain method.When the traditional circular rods adjacent to the centre of the cavities are replaced by the oval rods,the simulated results show that the waveguide mode region can be adjusted only by the alteration of the oval rods' obliquity.When the obliquity of the oval rods around one cavity is different from the obliquity of that around the adjacent cavities,the group velocities of the waveguide modes can be greatly reduced and the information of different frequencies can be shared and chosen at the same time by the waveguide branches with different structures.If the obliquities of the oval rods around two adjacent cavities are equal and they alternate between two values,the group velocities can be further reduced and a maximum value of 0.0008c(c is the light velocity in vacuum) can be acquired.
基金Project supported by the "985 project" (Grant Nos.98503-008006 and 98503-008017)the "211 project" of Ministry of Education of Chinathe Fundamental Research Funds for the Central Universities of China
文摘On the basis of two-dimensional amorphous photonic materials,we have designed a novel waveguide by inserting thinner cylindrical inclusions in the centre of basic hexagonal units of the amorphous structure along a given path.This waveguide in amorphous structure is similar to the coupled resonator optical waveguides in periodic photonic crystals.The transmission of this waveguide for S-polarized waves is investigated by a multiple-scattering method.Compared with the conventional waveguide by removing a line of cells from amorphous photonic materials,the guiding properties of this waveguide,including the transmissivity and bandwidth,are improved significantly.Then we study the effect of various types of positional disorder on the functionality of this device.Our results show that the waveguide performance is quite sensitive to the disorder located on the boundary layer of the waveguide,but robust against the disorder in the other area in amorphous structure except the waveguide border.This disorder effect in amorphous photonic materials is similar to the case in periodic photonic crystals.
基金Project supported by the National Natural Science Foundation of China (Grant No. 60877031)
文摘Based on the present coupled mode theory of the photonic crystal resonator array in this paper,we propose a novel side-coupled waveguide to achieve highly efficient coupling of photonic crystal devices.It is found that the coupling efficiency is sensitive to the interval,the total number and the quality factor of the resonator.Considering the coupling efficiency and the coupling region,we select five resonators with an interval of six lattice periods.By optimizing the structure parameters of the waveguide and resonator,the quality factors of the resonator can be modulated and the coupling efficiency of the side-coupled waveguide reaches 95.47% in theory.Compared with other coupling methods,the side-coupled waveguide can realize efficient coupling with a compact structure,a high level of integration and a low degree of operational difficulties.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 60336010 and 60537010). Acknowledgments The authors would like to thank Dr Han Wei-Hua, Dr Fan Zhong-Chao, and Mr Xing-Bo of the Institute of Semiconductors, Chinese Academy of Sciences, for their useful discussions and great help in the experiment and optical measurements.
基金Supported by the National Natural Science Foundation of China under Grant Nos 50872089,61077039 and 61377060the Research Grants Council of the Hong Kong Special Administrative Region of China under Grant No 11211014+1 种基金the Key Program for Research on Fundamental to Application and Leading Technology of Tianjin Science and Technology Commission of China under Grant No 11JCZDJC15500the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No 20100032110052
文摘Transmission spectra of triangular lattice photonic crystals milled in the top surface of an annealed protonexchange waveguide are numerically simulated.The effects of the finite depth,conical shape,trapezoidal shape and hybrid shape of holes are theoretically analyzed.Due to the difficulty of milling high aspect-ratio cylindrical holes in lithium niobate(LiNbO_3),a compromised solution is proposed to improve the overlap between shallow holes and the waveguide mode,and useful transmission spectra with strong contrast and sharp band edges are achieved.
基金supported by the National Natural Science Foundation of China(Grant No.31401136)the School Youth Fund of Henan University of Science and Technology,China(Grant No.2014QN045)
文摘With the method of replacing the surface layer of photonic crystal with tubes, a novel photonic crystal composite structure used as a tunable surface mode waveguide is designed. The tubes support tunable surface states. The tunable propagation capabilities of the structure are investigated by using the finite-difference time-domain. Simulation results show that the beam transmission distributions of the composite structure are sensitive to the frequency range of incident light and the surface morphology which can be modified by filling the tubes with different organic liquids. By adjusting the filler in tubes, the T-shaped, Y-shaped, and L-shaped propagations can be realized. The property can be applied to the tunable surface mode waveguide. Compared with a traditional single function photonic crystal waveguide, our designed structure not only has a small size, but also is a tunable device.
基金Project supported by the Special Grade of the Financial Support from the China Postdoctoral Science Foundation(Grant No.2016T90455)the China Postdoctoral Science Foundation(Grant No.2015M581790)the Chinese Jiangsu Planned Projects for Postdoctoral Research Funds,China(Grant No.1501016A)
文摘Recently, Zhang et al.(Chin. Phys. B 26 024208(2017)) investigated the band gap structures and semi-Dirac point of two-dimensional function photonic crystals, and the equations for the plane wave expansion method were induced to obtain the band structures. That report shows the band diagrams with the effects of function coefficient k and medium column r_a under TE and TM waves. The proposed results look correct at first glance, but the authors made some mistakes in their report. Thus, the calculated results in their paper are incorrect. According to our calculations, the errors in their report are corrected, and the correct band structures also are presented in this paper.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 60336010 and 60537010)
文摘This paper reports that a two-dimensional single-defect photonic crystal waveguide in the Γ -K direction with triangular lattice on a silicon-on-insulator substrate is fabricated by the combination of electron beam lithography and inductively coupled plasma etching. A ministop band (MSB) is observed by the measurement of transmission characteristics. It results from the coupling between the two modes with the same symmetry, which is analysed from the stimulated band diagram by the effective index and the two-dimensional plane wave expansion methods. The parameter working on the MSB is the ratio of the radius of air holes to the lattice constant, r/a. It is obtained that the critical r/a value determining the occurrence or disappearance of MSB is 0.36. When r/a is larger than or equal to 0.36, the MSB occurs. However, when r/a is smaller than 0.36, the MSB disappears.
文摘In this paper, an optical waveguide junction is introduced to reduce crosstalk based on a hexagonal structure of photonic crystals for TE modes. The wavelength is 1330 nm which is an important wavelength for optical fiber data transmission. Simulation results show that the proposed design exhibits a reduction of -50 dB in crosstalk. It translates to a considerable isolation improvement between two crossover waveguides. FDTD method is used to obtain the transmission coefficient.
文摘GaP terahertz (THz) two-dimensional (2D) photonic crystal (PC) waveguides with line defects were fabricated using inductively-coupled plasma reactive-ion etching (ICP-RIE) in Ar/Cl2 gas chemistries. THz-wave generation from the fabricated PC waveguides was demonstrated under collinear phase-matched difference-frequency generation (DFG), using Cr:Forsterite (Cr:F) lasers as the incident source. We compared the THz-wave output characteristics of the PC waveguides with that of GaP planar waveguides. The collinear phase-matching conditions in the DFG process were satisfied for 300- and 500-μm-wide PC waveguide structures at 0.7 and 0.6 THz, respectively. The additional output peaks that appeared near the edge of the photonic band gap, around 0.5 THz, were attributed to the guiding modes in the PC waveguide;no such peaks appeared in the non-patterned ridge waveguides. These experimental results suggest that the phonon-polariton confinement in THz-PC waveguides based on the GaP crystal could be used to enhance the nonlinear optical effect for THz-wave generation.
基金the Key-Area Research and Development Program of Guangdong Province of China(Grant No.2018B030325002)the National Natural Science Foundation of China(Grant No.62075129)+1 种基金the Open Project Program of SJTU-Pinghu Institute of Intelligent Optoelectronics(Grant No.2022SPIOE204)the Science and Technology on Metrology and Calibration Laboratory(Grant No.JLJK2022001B002)。
文摘Generation of hyperentangled photon pairs is investigated based on the lithium niobate straight waveguide.We propose to use the nonlinear optical process of spontaneous parametric down-conversion(SPDC)and a well-designed lithium niobate waveguide structure to generate a hyperentangled(in the polarization dimension and the energy-time dimension)two-photon state.By performing numerical simulations of the waveguide structure and calculating the possible polarization states,joint spectral amplitudes(JSA),and joint temporal amplitudes(JTA)of the generated photon pair,we show that the generated photon pair is indeed hyperentangled in both the polarization dimension and the energy-time dimension.
文摘In this paper, we have designed and simulated all-optical tristate Pauli X, Y and Z gates using 2D photonic crystal. Simple line and point defects have been used to design the structure. The performance of the structure has been analyzed and investigated by plane wave expansion(PWE) and finite difference time domain(FDTD) methods. Different performance parameters, namely contrast ratio(CR), rise time, fall time, delay time, response time and bit rate, have been calculated. The main advantage of the proposed design is that all the Pauli gates have been realized from a single structure. Due to compact size, fast response time, good CR and high bit rate, the proposed structure can be highly useful for optical computing, data processing and optical integrated circuits.
基金financial support from National Natural Science Foundation of China(No.61775120).
文摘Optical waveguides are far more than mere connecting elements in integrated optical systems and circuits.Benefiting from their high optical confinement and miniaturized footprints,waveguide structures established based on crystalline materials,particularly,are opening exciting possibilities and opportunities in photonic chips by facilitating their on-chip integration with different functionalities and highly compact photonic circuits.Femtosecond-laser-direct writing(FsLDW),as a true three-dimensional(3D)micromachining and microfabrication technology,allows rapid prototyping of on-demand waveguide geometries inside transparent materials via localized material modification.The success of FsLDW lies not only in its unsurpassed aptitude for realizing 3D devices but also in its remarkable material-independence that enables cross-platform solutions.This review emphasizes FsLDW fabrication of waveguide structures with 3D layouts in dielectric crystals.Their functionalities as passive and active photonic devices are also demonstrated and discussed.
文摘This paper presents four rings square, circular, and hexagonal photonic crystal fiber (PCF) geometry for analyzing different optical properties in a wavelength ranging from 800 nm to 1600 nm. These three types of geometry have been used for analyzing Effective area, Propagation constant, Confinement loss and Waveguide dispersion. Silica glass is chosen as background material and the cladding region is made of four air hole layers. COMSOL Multiphysics (v.5) software is used to simulate these proposed PCF geometries. From the numerical analysis, it is found that the effective area is small for hexagonal PCF geometry and large for square PCF geometry (11.827 μm2, 10.588 μm2 and 9.405 μm2 for square, circular, and hexagonal PCF geometry respectively). From the analysis, the Confinement loss is approximately zero at wavelength ranges from 800 nm to 1250 nm and approximately zero waveguide dispersion is achieved from 900 nm to 1500 nm for all the three PCF structures. Again, negative dispersion approximately −30.354 ps/(nm⋅km) is achieved for circular PCF structure at the wavelength of 900 nm.
基金Project supported by the National Key Basic Research and Development Programme of China (Grant No 2001CB6104), the National Center for Nanoscience and Technology, China (Grant No 2003CB7169) and the National Natural Science Foundation of China (Grant No 10474036).
基金supported by the National Natural Science Foundation of China(No.11075032)the National High Technology Research and Development Program of China(No.2011AA010204)
文摘Two-dimensional metallic photonic crystal slabs with square lattice are proposed to be used for the design of waveguide bandpass filters operating in millimeter to terahertz region.Filter characteristics are studied when rod radii and lattice constants are changed.Based on the frequency scaling technique,a series of higher frequency filters has been designed.By using laser drilling and welding processing techniques,a compact waveguide filter embedded in an EIA-WR10 waveguide with central frequency 145.5 GHz and3-dB bandwidth of 5.26 GHz is fabricated and measured.The measurement data agree well with the simulation prediction.
基金supported by the National Natural Science Foundation of China (Nos.10904176 and 11004169)the NMOE Project of China (Nos.200911002 and 2010110009)
文摘The light propagation characteristics through the annular coupled-resonator cavity waveguides are systematically analyzed by the finite-difference time-domain (FDTD) method. It is found that this kind of waveguide has more minbands owing to the increasing of the cavity’s size, compared with the traditional line-typed coupled-resonator waveguide. The group velocity of light propagation can be reduced for a further degree when the adjacent annular cavities are interlaced in the perpendicular direction, and a group velocity about 0.00067c (c is the light speed in vacuum) can be obtained.
基金supported by National Key R&D Program of China(No.2018YFA0306100)the National Natural Science Foundations of China(Nos.11874437,11704424)+2 种基金the Natural Science Foundation of Guangdong Province(Nos.2018B030311027,2017A030310004,2016A030310216)Guangzhou Science and Technology Project(No.201805010004)the National Natural Science Foundation of China(No.60123456)
文摘Quantum light sources serve as one of the key elements in quantum photonic technologies. Such sources made from semiconductor material, e.g., quantum dots (QDs), are particularly appealing because of their great potential of scalability enabled by the modern planar nanofabrication technologies. So far, non-classic light sources based on semiconductor QDs are currently outperforming their counterparts using nonlinear optical process, for instance, parametric down conversion and four-wave mixing. To fully exploring the potential of semiconductor QDs, it is highly desirable to integrate QDs with a variety of photonic nanostructures for better device performance due to the improved light-matter interaction. Among different designs, the photonic nanostructures exhibiting broad operation spectral range is particularly interesting to overcome the QD spectral inhomogeneity and exciton fine structure splitting for the generations of single-photon and entangled photon pair respectively. In this review, we focus on recent progress on high-performance semiconductor quantum light sources that is achieved by integrating single QDs with a variety of broadband photonic nanostructures i.e. waveguide, lens and low-Q cavity.