A four-channel integrated optical wavelength de-multiplexer is experimentally illustrated on a silicon-on-insulator （SO1） substrate. With the aid of cascaded micro-ring resonators, the whole performance of the wavel...A four-channel integrated optical wavelength de-multiplexer is experimentally illustrated on a silicon-on-insulator （SO1） substrate. With the aid of cascaded micro-ring resonators, the whole performance of the wavelength de- multiplexer is improved, such as 3 dB bandwidth and channel crosstalk. Based on the transform matrix theory, a four-channel wavelength de-multiplexer with average channel spacing 4.5±0.5 nm （3 dB bandwidth - 2 ± 0.5 nm） is demonstrated at telecommunication bands. For each channel, the extinction at the adjacent channel is below -39dB and the out-of-band rejection ratio is up to 40dB. The channel dropping loss is below 5dB in the five FSR spectral response periods （near 100 nm）.展开更多
This study investigates the application of miniature quantum references within small-scale optical atomic frequency standards,utilizing a diminutive^(87)Rb glass cell,dimensions of 6 mm×6 mm×6 mm,to establis...This study investigates the application of miniature quantum references within small-scale optical atomic frequency standards,utilizing a diminutive^(87)Rb glass cell,dimensions of 6 mm×6 mm×6 mm,to establish a quantum frequency standard.'By employing the transition spectrum from 5^(2)S_(1/2)F=2 to 5^(2)P_(3/2)F=3,this study successfully demonstrates the development of a compact rubidium atomic optical frequency standard via modulation transfer spectroscopy(MTS).Subsequent to frequency stabilization,the 780 nm clock laser exhibits a linewidth of 6.9 k Hz,and its out-of-loop short-term stability reaches4.1×10^(-13)@1 s,as confirmed through beat frequency analysis.This research not only provides a practical blueprint for the development of small optical atomic frequency standards but also lays down essential groundwork for future advancements in chip-level optical frequency standard technologies.展开更多
We theoretically propose blue-detuned optical trapping for neutral atoms via strong near-field interfacing in a plasmonic nanohole array. The optical field at resonance forms a nanoscale-trap potential with an FWHM of...We theoretically propose blue-detuned optical trapping for neutral atoms via strong near-field interfacing in a plasmonic nanohole array. The optical field at resonance forms a nanoscale-trap potential with an FWHM of 200 nm and about ～370 nm away from the nanohole; thus, a stable 3 D atom trapping independent of the surface potential is demonstrated. The effective trap depth is more than 1 m K when the optical power of trapping light is only about 0.5 m W, while the atom scattering rate is merely about 3.31 s^(-1), and the trap lifetime is about 800 s.This compact plasmonic structure provides high uniformity of trap depths and a two-layer array of atom nanotraps, which should have important applications in the manipulation of cold atoms and collective resonance fluorescence.展开更多
A two-dimensional(2D) optical true-time delay(TTD) beam-forming system using a compact fiber grating prism(FGP) for a planar phased array antenna(PAA) is proposed. The optical beam-forming system mainly consists of a ...A two-dimensional(2D) optical true-time delay(TTD) beam-forming system using a compact fiber grating prism(FGP) for a planar phased array antenna(PAA) is proposed. The optical beam-forming system mainly consists of a TTD unit based on the same compact FGP, one tunable laser for elevation beam steering, and a controlled wavelength converter for azimuth beam steering. A planar PAA using such 2D optical TTD unit has advantages such as compactness, low bandwidth requirement for tunable laser sources, and potential for large-scale system implementations. The proof-of-concept experiment results demonstrate the feasibility of the proposed scheme.展开更多
Braille serves as an efficient means for visually impaired individuals to access textual information and engage in communication.However,the process of reading Braille can often be cumbersome and time-intensive,partic...Braille serves as an efficient means for visually impaired individuals to access textual information and engage in communication.However,the process of reading Braille can often be cumbersome and time-intensive,particularly in bidirectional human-machine interaction.In this work,a compact optical device for contactless detection of Braille is fabricated and characterized.The GaN-on-sapphire chip,which employs monolithic integration,serves as the core for both light emission and photodetection,significantly reducing its overall footprint.The incorporation of the semiellipsoid epoxy lens with optimized dimensions ensures consistent and accurate detection.The sensing device demonstrates high stability and fast response through its line-scanning capabilities on Braille codes.The captured signals are analyzed using a microcontroller,and the Braille recognition results are wirelessly transmitted to a portable mobile device,enabling the conversion into audio and visual formats.This innovative design not only facilitates Braille reading but also holds the potential to advance human-machine interaction.展开更多
Holographic near-eye augmented reality(AR)displays featuring tilted inbound/outbound angles on compact optical combiners hold significant potential yet often struggle to deliver satisfying image quality.This is primar...Holographic near-eye augmented reality(AR)displays featuring tilted inbound/outbound angles on compact optical combiners hold significant potential yet often struggle to deliver satisfying image quality.This is primarily attributed to two reasons:the lack of a robust off-axis-supported phase hologram generation algorithm;and the suboptimal performance of ill-tuned hardware parts such as imperfect holographic optical elements(HOEs).To address these issues,we incorporate a gradient descent-based phase retrieval algorithm with spectrum remapping,allowing for precise hologram generation with wave propagation between nonparallel planes.Further,we apply a camera-calibrated propagation scheme to iteratively optimize holograms,mitigating imperfections arising from the defects in the HOE fabrication process and other hardware parts,thereby significantly lifting the holographic image quality.We build an off-axis holographic near-eye display prototype using off-the-shelf light engine parts and a customized full-color HOE,demonstrating state-of-the-art virtual reality and AR display results.展开更多
基金Supported by the National High Technology Research and Development Program of China under Grant No 2015AA016904the National Key Research and Development Plan of China under Grant No 2016YFB0402502the National Natural Science Foundation of China under Grant No 61275065
文摘A four-channel integrated optical wavelength de-multiplexer is experimentally illustrated on a silicon-on-insulator （SO1） substrate. With the aid of cascaded micro-ring resonators, the whole performance of the wavelength de- multiplexer is improved, such as 3 dB bandwidth and channel crosstalk. Based on the transform matrix theory, a four-channel wavelength de-multiplexer with average channel spacing 4.5±0.5 nm （3 dB bandwidth - 2 ± 0.5 nm） is demonstrated at telecommunication bands. For each channel, the extinction at the adjacent channel is below -39dB and the out-of-band rejection ratio is up to 40dB. The channel dropping loss is below 5dB in the five FSR spectral response periods （near 100 nm）.
文摘This study investigates the application of miniature quantum references within small-scale optical atomic frequency standards,utilizing a diminutive^(87)Rb glass cell,dimensions of 6 mm×6 mm×6 mm,to establish a quantum frequency standard.'By employing the transition spectrum from 5^(2)S_(1/2)F=2 to 5^(2)P_(3/2)F=3,this study successfully demonstrates the development of a compact rubidium atomic optical frequency standard via modulation transfer spectroscopy(MTS).Subsequent to frequency stabilization,the 780 nm clock laser exhibits a linewidth of 6.9 k Hz,and its out-of-loop short-term stability reaches4.1×10^(-13)@1 s,as confirmed through beat frequency analysis.This research not only provides a practical blueprint for the development of small optical atomic frequency standards but also lays down essential groundwork for future advancements in chip-level optical frequency standard technologies.
基金National Key Basic Research Program(2013CB328700)National Natural Science Foundation of China(NSFC)(11525414,11374025,91221304)
文摘We theoretically propose blue-detuned optical trapping for neutral atoms via strong near-field interfacing in a plasmonic nanohole array. The optical field at resonance forms a nanoscale-trap potential with an FWHM of 200 nm and about ～370 nm away from the nanohole; thus, a stable 3 D atom trapping independent of the surface potential is demonstrated. The effective trap depth is more than 1 m K when the optical power of trapping light is only about 0.5 m W, while the atom scattering rate is merely about 3.31 s^(-1), and the trap lifetime is about 800 s.This compact plasmonic structure provides high uniformity of trap depths and a two-layer array of atom nanotraps, which should have important applications in the manipulation of cold atoms and collective resonance fluorescence.
基金supported by the National "973" Project of China(Nos.2010CB328202,2010CB328204,and 2012CB315604)the National Natural Science Foundation of China(Nos.61271191 and 61001124)+3 种基金the National "863" Project of China(No.2012AA011302)the Program for New Century Excellent Talents in University(No.NCET-12-0793)the Beijing Nova Program(No.2011065)the Fundamental Research Funds for the Central Universities
文摘A two-dimensional(2D) optical true-time delay(TTD) beam-forming system using a compact fiber grating prism(FGP) for a planar phased array antenna(PAA) is proposed. The optical beam-forming system mainly consists of a TTD unit based on the same compact FGP, one tunable laser for elevation beam steering, and a controlled wavelength converter for azimuth beam steering. A planar PAA using such 2D optical TTD unit has advantages such as compactness, low bandwidth requirement for tunable laser sources, and potential for large-scale system implementations. The proof-of-concept experiment results demonstrate the feasibility of the proposed scheme.
基金financial support from the National Natural Science Foundation of China under Grant 12074170in part by the Shenzhen Fundamental Research Program under Grant JCYJ20220530113201003.
文摘Braille serves as an efficient means for visually impaired individuals to access textual information and engage in communication.However,the process of reading Braille can often be cumbersome and time-intensive,particularly in bidirectional human-machine interaction.In this work,a compact optical device for contactless detection of Braille is fabricated and characterized.The GaN-on-sapphire chip,which employs monolithic integration,serves as the core for both light emission and photodetection,significantly reducing its overall footprint.The incorporation of the semiellipsoid epoxy lens with optimized dimensions ensures consistent and accurate detection.The sensing device demonstrates high stability and fast response through its line-scanning capabilities on Braille codes.The captured signals are analyzed using a microcontroller,and the Braille recognition results are wirelessly transmitted to a portable mobile device,enabling the conversion into audio and visual formats.This innovative design not only facilitates Braille reading but also holds the potential to advance human-machine interaction.
基金National Key Research and Development Program of China(2021YFB2802200)National Natural Science Foundation of China(62322217,62005154)+1 种基金Natural Science Foundation of Shanghai Municipality(20ZR1420500)University Grants Committee(ECS27212822,GRF 17208023)。
文摘Holographic near-eye augmented reality(AR)displays featuring tilted inbound/outbound angles on compact optical combiners hold significant potential yet often struggle to deliver satisfying image quality.This is primarily attributed to two reasons:the lack of a robust off-axis-supported phase hologram generation algorithm;and the suboptimal performance of ill-tuned hardware parts such as imperfect holographic optical elements(HOEs).To address these issues,we incorporate a gradient descent-based phase retrieval algorithm with spectrum remapping,allowing for precise hologram generation with wave propagation between nonparallel planes.Further,we apply a camera-calibrated propagation scheme to iteratively optimize holograms,mitigating imperfections arising from the defects in the HOE fabrication process and other hardware parts,thereby significantly lifting the holographic image quality.We build an off-axis holographic near-eye display prototype using off-the-shelf light engine parts and a customized full-color HOE,demonstrating state-of-the-art virtual reality and AR display results.
