We report a type-I Ga Sb-based laterally coupled distributed-feedback（LC-DFB） laser with shallow-etched gratings operating a continuous wave at room temperature without re-growth process. Second-order Bragg gratings...We report a type-I Ga Sb-based laterally coupled distributed-feedback（LC-DFB） laser with shallow-etched gratings operating a continuous wave at room temperature without re-growth process. Second-order Bragg gratings are fabricated alongside the ridge waveguide by interference lithography. Index-coupled LC-DFB laser with a cavity of 1500 μm achieves single longitudinal mode continuous-wave operation at 20℃ with side mode suppression ratio（SMSR） as high as 24 dB.The maximum single mode continuous-wave output power is about 10 mW at room temperature（uncoated facet）. A low threshold current density of 230 A/cm^2 is achieved with differential quantum efficiency estimated to be 93 mW/A. The laser shows a good wavelength stability against drive current and working temperature.展开更多
The use of an attenuated total reflection-coupling mode of prism coated with metal film to excite the interference of the surface plasmon polaritons （SPPs） was proposed for periodic patterning with a resolution of s...The use of an attenuated total reflection-coupling mode of prism coated with metal film to excite the interference of the surface plasmon polaritons （SPPs） was proposed for periodic patterning with a resolution of subwavelength scale. High intensity of electric field can be obtained because of the coupling between SPPs and evanescence under a resonance condition, which can reduce exposure time and improve contrast. In this paper, several critical parameters for maskless surface plasmon resonant lithography are described, and the preliminary simulation based on a finite difference timedomain technique agrees well with the theoretical analysis, which demonstrates this scheme and provides the theoretical basis for further experiments.展开更多
We report the fabrication of 4-inch nano patterned wafer by two-beam laser interference lithography and analyze the uniformity in detail. The profile of the dots array with a period of 800 nm divided into five regions...We report the fabrication of 4-inch nano patterned wafer by two-beam laser interference lithography and analyze the uniformity in detail. The profile of the dots array with a period of 800 nm divided into five regions is characterized by a scanning electron microscope. The average size in each region ranges from 270 nm to 320 nm,and the deviation is almost 4%, which is approaching the applicable value of 3% in the industrial process. We simulate the two-beam laser interference lithography system with MATLAB software and then calculate the distribution of light intensity around the 4 inch area. The experimental data fit very well with the calculated results. Analysis of the experimental data and calculated data indicates that laser beam quality and space filter play important roles in achieving a periodical nanoscale pattern with high uniformity and large area. There is the potential to obtain more practical applications.展开更多
The soft X-ray interference lithography(XIL) branch beamline at Shanghai Synchrotron Radiation Facility(SSRF) is briefly introduced in this article. It is designed for obtaining 1D(line/space) and 2D(dot/hole)periodic...The soft X-ray interference lithography(XIL) branch beamline at Shanghai Synchrotron Radiation Facility(SSRF) is briefly introduced in this article. It is designed for obtaining 1D(line/space) and 2D(dot/hole)periodic nanostructures by using two or more coherent extreme ultraviolet(EUV) beams from an undulator source. A transmission-diffraction-grating type of interferometer is used at the end station. Initial results reveal high performance of the beamline, with 50 nm half-pitch 1D and 2D patterns from a single exposure area of400 μm× 400 μm. XIL is used in a growing number of areas, such as EUV resist test, surface enhanced Raman scattering(SERS) and color filter plasmonic devices. By using highly coherent EUV beam, broadband coherent diffractive imaging can be performed on the XIL beamline. Well reconstructed pinhole of φ20 μm has been realized.展开更多
This paper introduces the recent progress in methodologies and their related applications based on the soft x-ray interference lithography beamline in the Shanghai synchrotron radiation facility.Dual-beam,multibeam in...This paper introduces the recent progress in methodologies and their related applications based on the soft x-ray interference lithography beamline in the Shanghai synchrotron radiation facility.Dual-beam,multibeam interference lithography and Talbot lithography have been adopted as basic methods in the beamline.To improve the experimental performance,a precise real-time vibration evaluation system has been established;and the lithography stability has been greatly improved.In order to meet the demands for higher resolution and practical application,novel experimental methods have been developed,such as high-order diffraction interference exposure,high-aspect-ratio and large-area stitching exposure,and parallel direct writing achromatic Talbot lithography.As of now,a 25 nm half-pitch pattern has been obtained;and a cm2 exposure area has been achieved in practical samples.The above methods have been applied to extreme ultraviolet photoresist evaluation,photonic crystal and surface plasmonic effect research,and so on.展开更多
A surface plasmon interference lithography assisted by a Fabry-Perot （F-P） cavity composed of subwavelength metal gratings and a thin metal fihn is proposed to fabricate high-quality nanopatterns. The calculated res...A surface plasmon interference lithography assisted by a Fabry-Perot （F-P） cavity composed of subwavelength metal gratings and a thin metal fihn is proposed to fabricate high-quality nanopatterns. The calculated results indicate that uniform straight interference fringes with high contrast and high electric-field intensity are formed in the resist under the F-P cavity. The analyses of spatial frequency spectra illuminate the physical mechanism of the formation for the interference fringes. The influence of the F-P cavity spacing is discussed in detail. Moreover, the error analyses reveal that all parameters except the metal grating period in this scheme can bear large tolerances for the device fabrication.展开更多
A single-beam interference-lithography scheme is demonstrated for the fabrication of large-area slant gratings, which requires exposure of the photoresist thin film spin-coated on a glass plate with polished side-wall...A single-beam interference-lithography scheme is demonstrated for the fabrication of large-area slant gratings, which requires exposure of the photoresist thin film spin-coated on a glass plate with polished side-walls to a single laser beam in the ultraviolet and requires small coherence length of the laser. No additional beam splitting scheme and no adjustments for laser-beam overlapping and for optical path-length balancing are needed. Bragg-angle diffractions are observed as strong optical extinction that is tunable with changing the angle of incidence. This device is important for the design of efficient filters, beam splitters, and photonic devices.展开更多
Large-area gratings play a crucial role in various engineering fields.However,traditional interference lithography is limited by the size of optical component apertures,making large-area fabrication a challenging task...Large-area gratings play a crucial role in various engineering fields.However,traditional interference lithography is limited by the size of optical component apertures,making large-area fabrication a challenging task.Here,a method for fabricating laser interference lithography pattern arrays with a global alignment reference strategy is proposed.This approach enables alignment of each area of the laser interference lithography pattern arrays,including phase,period,and tilt angle.Two reference gratings are utilized:one is detached from the substrate,while the other remains fixed to it.To achieve global alignment,the exposure area is adjusted by alternating between moving the beam and the substrate.In our experiment,a 3×3 regions grating array was fabricated,and the−1st-order diffraction wavefront measured by the Fizeau interferometer exhibited good continuity.This technique enables effective and efficient alignment with high accuracy across any region in an interference lithography pattern array on large substrates.It can also serve as a common technique for fabricating various types of periodic structures by rotating the substrate.展开更多
Laser interference lithography is an attractive method for the fabrication of a large-area two-dimensional planar scale grating,which can be employed as a scale for multi-axis optical encoders or a diffractive optical...Laser interference lithography is an attractive method for the fabrication of a large-area two-dimensional planar scale grating,which can be employed as a scale for multi-axis optical encoders or a diffractive optical element in many types of optical sensors.Especially,optical configurations such as Lloyd's mirror interferometer based on the division of wavefront method can generate interference fringe fields for the patterning of grating pattern structures at a single exposure in a stable manner.For the fabrication of a two-dimensional scale grating to be used in a planar/surface encoder,an orthogonal two-axis Lloyd's mirror interferometer,which has been realized through innovation to Lloyd’s mirror interferometer,has been developed.In addition,the concept of the patterning of the two-dimensional orthogonal pattern structure at a single exposure has been extended to the non-orthogonal two-axis Lloyd’s mirror interferometer.Furthermore,the optical setup for the non-orthogonal two-axis Lloyd's mirror interferometer has been optimized for the fabrication of a large-area scale grating.In this review article,principles of generating interference fringe fields for the fabrication of a scale grating based on the interference lithography are reviewed,while focusing on the fabrication of a two-dimensional scale grating for planar/surface encoders.Verification of the pitch of the fabricated pattern structures,whose accuracy strongly affects the performance of planar/surface encoders,is also an important task to be addressed.In this paper,major methods for the evaluation of a grating pitch are also reviewed.展开更多
To obtain a good interference fringe contrast and high fidelity,an automated beam iterative alignment is achieved in scanning beam interference lithography(SBIL).To solve the problem of alignment failure caused by a l...To obtain a good interference fringe contrast and high fidelity,an automated beam iterative alignment is achieved in scanning beam interference lithography(SBIL).To solve the problem of alignment failure caused by a large beam angle(or position)overshoot exceeding the detector range while also speeding up the convergence,a weighted iterative algorithm using a weight parameter that is changed linearly piecewise is proposed.The changes in the beam angle and position deviation during the alignment process based on different iterative algorithms are compared by experiment and simulation.The results show that the proposed iterative algorithm can be used to suppress the beam angle(or position)overshoot,avoiding alignment failure caused by over-ranging.In addition,the convergence speed can be effectively increased.The algorithm proposed can optimize the beam alignment process in SBIL.展开更多
Surface microstructures impart various useful properties to objects,for example,improving optical characteristics,wettability,and sliding properties.It is well known that biomimicking relief structures are effective i...Surface microstructures impart various useful properties to objects,for example,improving optical characteristics,wettability,and sliding properties.It is well known that biomimicking relief structures are effective in making such properties arise and have been studied to be applied to various devices.Furthermore,they are expected to be utilized not only for improving a particular property but also for adding more complex functions on a device's urface by fabricating different multi-functional structures on a single surface in the future.However,to begin with,artificially fabricating such biomimicking special functional relief is difficult.One typical feature of biomimicking surfaces is the dual-scale structure,the smaller one of which is less than 200 nm.Moreover,in the case of realizing the more complex devices,it is necessary to fabricate various forms as changing process conditions dynamically.In this study,we proposed and developed a flexible evanescent wave interference lithography system as a novel fabrication method,which allows us to realize the fabrication of sub-half-wavelength complex relief structures.Firstly,we theoretically analyzed the fundamental behavior of the fabricated structure and found that the proposed concept has the potential to realize one of the target complex structures.Secondly,we developed the proposed system with high process flexibility,in which the number of beams,the azimuth angles,and the polarization can be simply manipulated.Finally,we validated the concept of the designed system by some experiments,where we fabricated dual-scale structures with 840-nm and 190-nm fringe patterns simultaneously.展开更多
基金Project supported by the National Key Basic Research Program of China(Grant Nos.2014CB643903 and 2013CB932904)the National Special Funds for the Development of Major Research Equipment and Instruments,China(Grant No.2012YQ140005)+1 种基金the National Natural Science Foundation of China(Grant Nos.61435012,61274013,61306088,and 61290303)the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB01010200)
文摘We report a type-I Ga Sb-based laterally coupled distributed-feedback（LC-DFB） laser with shallow-etched gratings operating a continuous wave at room temperature without re-growth process. Second-order Bragg gratings are fabricated alongside the ridge waveguide by interference lithography. Index-coupled LC-DFB laser with a cavity of 1500 μm achieves single longitudinal mode continuous-wave operation at 20℃ with side mode suppression ratio（SMSR） as high as 24 dB.The maximum single mode continuous-wave output power is about 10 mW at room temperature（uncoated facet）. A low threshold current density of 230 A/cm^2 is achieved with differential quantum efficiency estimated to be 93 mW/A. The laser shows a good wavelength stability against drive current and working temperature.
基金supported by the National Basic Research of China (Grant No 2006CD302900-2)the National Natural Science Foundation of China (Grant No 60676024)the Specialized Research Fund of China for the Doctoral Program of Higher Education (Grant No 20060610006)
文摘The use of an attenuated total reflection-coupling mode of prism coated with metal film to excite the interference of the surface plasmon polaritons （SPPs） was proposed for periodic patterning with a resolution of subwavelength scale. High intensity of electric field can be obtained because of the coupling between SPPs and evanescence under a resonance condition, which can reduce exposure time and improve contrast. In this paper, several critical parameters for maskless surface plasmon resonant lithography are described, and the preliminary simulation based on a finite difference timedomain technique agrees well with the theoretical analysis, which demonstrates this scheme and provides the theoretical basis for further experiments.
基金Supported by the Scientific Equipment Research Program of Chinese Academy of Sciences under Grant No 2014Y4201449
文摘We report the fabrication of 4-inch nano patterned wafer by two-beam laser interference lithography and analyze the uniformity in detail. The profile of the dots array with a period of 800 nm divided into five regions is characterized by a scanning electron microscope. The average size in each region ranges from 270 nm to 320 nm,and the deviation is almost 4%, which is approaching the applicable value of 3% in the industrial process. We simulate the two-beam laser interference lithography system with MATLAB software and then calculate the distribution of light intensity around the 4 inch area. The experimental data fit very well with the calculated results. Analysis of the experimental data and calculated data indicates that laser beam quality and space filter play important roles in achieving a periodical nanoscale pattern with high uniformity and large area. There is the potential to obtain more practical applications.
基金Supported by the National Key Basic Research Program of China(No.2012CB825700)the Open Research Project of Large Scientific Facility from Chinese Academy of Sciences:Study on Self-Assembly Technology and Nanometer Array with Ultra-high Density
文摘The soft X-ray interference lithography(XIL) branch beamline at Shanghai Synchrotron Radiation Facility(SSRF) is briefly introduced in this article. It is designed for obtaining 1D(line/space) and 2D(dot/hole)periodic nanostructures by using two or more coherent extreme ultraviolet(EUV) beams from an undulator source. A transmission-diffraction-grating type of interferometer is used at the end station. Initial results reveal high performance of the beamline, with 50 nm half-pitch 1D and 2D patterns from a single exposure area of400 μm× 400 μm. XIL is used in a growing number of areas, such as EUV resist test, surface enhanced Raman scattering(SERS) and color filter plasmonic devices. By using highly coherent EUV beam, broadband coherent diffractive imaging can be performed on the XIL beamline. Well reconstructed pinhole of φ20 μm has been realized.
基金This work was performed at the SSRF XIL beamline(BL08U1B)Financial support was provided by the National Key R&D Program of China(2017YFA0206001)+1 种基金the National Key Basic Research Program of the China Science and Technology Commission of Shanghai Municipality(17JC1400802)the National Natural Science Foundation of China(Nos.11775291,11875314).
文摘This paper introduces the recent progress in methodologies and their related applications based on the soft x-ray interference lithography beamline in the Shanghai synchrotron radiation facility.Dual-beam,multibeam interference lithography and Talbot lithography have been adopted as basic methods in the beamline.To improve the experimental performance,a precise real-time vibration evaluation system has been established;and the lithography stability has been greatly improved.In order to meet the demands for higher resolution and practical application,novel experimental methods have been developed,such as high-order diffraction interference exposure,high-aspect-ratio and large-area stitching exposure,and parallel direct writing achromatic Talbot lithography.As of now,a 25 nm half-pitch pattern has been obtained;and a cm2 exposure area has been achieved in practical samples.The above methods have been applied to extreme ultraviolet photoresist evaluation,photonic crystal and surface plasmonic effect research,and so on.
基金Supported by the Natural Science Foundation of Hebei Province under Grant Nos A2013402069 and A2013402081
文摘A surface plasmon interference lithography assisted by a Fabry-Perot （F-P） cavity composed of subwavelength metal gratings and a thin metal fihn is proposed to fabricate high-quality nanopatterns. The calculated results indicate that uniform straight interference fringes with high contrast and high electric-field intensity are formed in the resist under the F-P cavity. The analyses of spatial frequency spectra illuminate the physical mechanism of the formation for the interference fringes. The influence of the F-P cavity spacing is discussed in detail. Moreover, the error analyses reveal that all parameters except the metal grating period in this scheme can bear large tolerances for the device fabrication.
文摘A single-beam interference-lithography scheme is demonstrated for the fabrication of large-area slant gratings, which requires exposure of the photoresist thin film spin-coated on a glass plate with polished side-walls to a single laser beam in the ultraviolet and requires small coherence length of the laser. No additional beam splitting scheme and no adjustments for laser-beam overlapping and for optical path-length balancing are needed. Bragg-angle diffractions are observed as strong optical extinction that is tunable with changing the angle of incidence. This device is important for the design of efficient filters, beam splitters, and photonic devices.
基金supported by the National Natural Science Foundation of China(no.62275142)the Shenzhen Stable Supporting Program(no.WDZC20231124201906001).
文摘Large-area gratings play a crucial role in various engineering fields.However,traditional interference lithography is limited by the size of optical component apertures,making large-area fabrication a challenging task.Here,a method for fabricating laser interference lithography pattern arrays with a global alignment reference strategy is proposed.This approach enables alignment of each area of the laser interference lithography pattern arrays,including phase,period,and tilt angle.Two reference gratings are utilized:one is detached from the substrate,while the other remains fixed to it.To achieve global alignment,the exposure area is adjusted by alternating between moving the beam and the substrate.In our experiment,a 3×3 regions grating array was fabricated,and the−1st-order diffraction wavefront measured by the Fizeau interferometer exhibited good continuity.This technique enables effective and efficient alignment with high accuracy across any region in an interference lithography pattern array on large substrates.It can also serve as a common technique for fabricating various types of periodic structures by rotating the substrate.
基金supported by the Japan Society for the Promotion of Science(JSPS).The author would like to thank Professor Wei Gao(Tohoku University,Japan)for the fruitful discussions and valuable comments on the topic of this review article.
文摘Laser interference lithography is an attractive method for the fabrication of a large-area two-dimensional planar scale grating,which can be employed as a scale for multi-axis optical encoders or a diffractive optical element in many types of optical sensors.Especially,optical configurations such as Lloyd's mirror interferometer based on the division of wavefront method can generate interference fringe fields for the patterning of grating pattern structures at a single exposure in a stable manner.For the fabrication of a two-dimensional scale grating to be used in a planar/surface encoder,an orthogonal two-axis Lloyd's mirror interferometer,which has been realized through innovation to Lloyd’s mirror interferometer,has been developed.In addition,the concept of the patterning of the two-dimensional orthogonal pattern structure at a single exposure has been extended to the non-orthogonal two-axis Lloyd’s mirror interferometer.Furthermore,the optical setup for the non-orthogonal two-axis Lloyd's mirror interferometer has been optimized for the fabrication of a large-area scale grating.In this review article,principles of generating interference fringe fields for the fabrication of a scale grating based on the interference lithography are reviewed,while focusing on the fabrication of a two-dimensional scale grating for planar/surface encoders.Verification of the pitch of the fabricated pattern structures,whose accuracy strongly affects the performance of planar/surface encoders,is also an important task to be addressed.In this paper,major methods for the evaluation of a grating pitch are also reviewed.
基金The research was supported by the National Natural Science Foundation of China(NSFC)(Grant No.61227901)Jilin Province Science&Technology Development Program Project in China(Grant No.20190103157JH).
文摘To obtain a good interference fringe contrast and high fidelity,an automated beam iterative alignment is achieved in scanning beam interference lithography(SBIL).To solve the problem of alignment failure caused by a large beam angle(or position)overshoot exceeding the detector range while also speeding up the convergence,a weighted iterative algorithm using a weight parameter that is changed linearly piecewise is proposed.The changes in the beam angle and position deviation during the alignment process based on different iterative algorithms are compared by experiment and simulation.The results show that the proposed iterative algorithm can be used to suppress the beam angle(or position)overshoot,avoiding alignment failure caused by over-ranging.In addition,the convergence speed can be effectively increased.The algorithm proposed can optimize the beam alignment process in SBIL.
文摘Surface microstructures impart various useful properties to objects,for example,improving optical characteristics,wettability,and sliding properties.It is well known that biomimicking relief structures are effective in making such properties arise and have been studied to be applied to various devices.Furthermore,they are expected to be utilized not only for improving a particular property but also for adding more complex functions on a device's urface by fabricating different multi-functional structures on a single surface in the future.However,to begin with,artificially fabricating such biomimicking special functional relief is difficult.One typical feature of biomimicking surfaces is the dual-scale structure,the smaller one of which is less than 200 nm.Moreover,in the case of realizing the more complex devices,it is necessary to fabricate various forms as changing process conditions dynamically.In this study,we proposed and developed a flexible evanescent wave interference lithography system as a novel fabrication method,which allows us to realize the fabrication of sub-half-wavelength complex relief structures.Firstly,we theoretically analyzed the fundamental behavior of the fabricated structure and found that the proposed concept has the potential to realize one of the target complex structures.Secondly,we developed the proposed system with high process flexibility,in which the number of beams,the azimuth angles,and the polarization can be simply manipulated.Finally,we validated the concept of the designed system by some experiments,where we fabricated dual-scale structures with 840-nm and 190-nm fringe patterns simultaneously.
