Volume: 19 Issue 12
25 Article(s)

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Research Articles
Atomic and Molecular Optics
Uncertainty evaluation of the second-order Zeeman shift of a transportable 87Rb atomic fountain clock
Henan Cheng, Siminda Deng, Zhen Zhang, Jingfeng Xiang, Jingwei Ji, Wei Ren, Tang Li, Qiuzhi Qu, Liang Liu, and Desheng Lü
Chinese Optics Letters
  • Publication Date: Sep. 02, 2021
  • Vol.19 Issue, 12 120201 (2021)
Recognizing local artifacts in two-photon imaging of dendrites beneath blood vessels in vivo
Cheng Jin, Ruheng Shi, Chi Liu, and Lingjie Kong
Chinese Optics Letters
  • Publication Date: Sep. 09, 2021
  • Vol.19 Issue, 12 121701 (2021)
Fiber Optics and Optical Communications
Robust integration of nitrogen-vacancy centers in nanodiamonds to optical fiber and its application in all-optical thermometry | Editors' Pick
Ce Bian, Minxuan Li, Wei Cao, Manli Hu, Zhiqin Chu, and Ruohui Wang
In this Letter, we developed a robust method for integrating nanodiamonds (NDs) to optical fiber. The NDs, containing nitrogen-vacancy (NV) centers, were uniformly mixed with UV adhesive before coating the end surface of a multimode fiber as a hemispherical film. The excitation and collection efficiency of NV fluorescence can be enhanced by increasing the thickness of UV adhesive film and additional aluminum film deposition. The fiber-based quantum sensor was also experimentally demonstrated for all-optical thermometry application. The variation of the refractive index of UV adhesive under different temperatures will also affect the NV collection efficiency by changing the light confinement. The demonstrated facile integration approach paves the way for developing fiber-based quantum thermometry and magnetometry.
Chinese Optics Letters
  • Publication Date: Sep. 22, 2021
  • Vol.19 Issue, 12 120601 (2021)
10 Gb/s free space optical interconnect with broadcasting capability enabled by a silicon integrated optical phased array
Quan You, Daigao Chen, Xi Xiao, and Shaohua Yu
Chinese Optics Letters
  • Publication Date: Nov. 04, 2021
  • Vol.19 Issue, 12 120602 (2021)
Imaging Systems and Image Processing
Fine edge detection in single-pixel imaging
Liyu Zhou, Xianwei Huang, Qin Fu, Xuanpengfan Zou, Yanfeng Bai, and Xiquan Fu
Chinese Optics Letters
  • Publication Date: Sep. 15, 2021
  • Vol.19 Issue, 12 121101 (2021)
Infrared and Terahertz Photonics
Continuous-wave terahertz diffraction tomography for measuring three-dimensional refractive index maps
Dayong Wang, Xiaoyu Jin, Jie Zhao, Yunxin Wang, Lu Rong, and John J. Healy
Chinese Optics Letters
  • Publication Date: Sep. 09, 2021
  • Vol.19 Issue, 12 123701 (2021)
Integrated Optics
High-performance ultra-compact polarization splitter-rotators based on dual-etching and tapered asymmetrical directional coupler
Changjian Xie, Xihua Zou, Fang Zou, and Yong Zhang
Chinese Optics Letters
  • Publication Date: Sep. 14, 2021
  • Vol.19 Issue, 12 121301 (2021)
Lasers, Optical Amplifiers, and Laser Optics
Low-noise amplification of dissipative Kerr soliton microcomb lines via optical injection locking lasers
Qiang Zhang, Boyuan Liu, Qin Wen, Jinhui Qin, Yong Geng, Qiang Zhou, Guangwei Deng, Kun Qiu, and Heng Zhou
Chinese Optics Letters
  • Publication Date: Sep. 14, 2021
  • Vol.19 Issue, 12 121401 (2021)
Q-switched mode-locked multimode fiber laser based on a graphene-deposited multimode microfiber | On the Cover
Jia-Wen Wu, Yu-Xin Gao, Xu-Bin Lin, Jin-Gan Long, Hu Cui, Zhi-Chao Luo, Wen-Cheng Xu, and Ai-Ping Luo
We report Q-switched mode-locked (QML) pulses generation in an Yb-doped multimode fiber (MMF) laser by using a graphene-deposited multimode microfiber (GMM) for the first time, to the best of our knowledge. The single-wavelength QML operation with the central wavelength tunable from 1028.81 nm to 1039.20 nm and the dual-wavelength QML operation with the wavelength spacing tunable from 0.93 nm to 5.79 nm are achieved due to the multimode interference filtering effect induced by the few-mode fiber and MMF structure and the GMM in the cavity. Particularly, in the single-wavelength QML operation, the fifth harmonic is also realized owing to the high nonlinear effect of the GMM. The obtained results indicate that the QML pulses can be generated in the MMF laser, and such a flexible tunable laser has promising applications in optical sensing, measuring, and laser processing.
Chinese Optics Letters
  • Publication Date: Sep. 17, 2021
  • Vol.19 Issue, 12 121402 (2021)
Non-mechanical beam scanner based on VCSEL integrated amplifier with resonant wavelength detuning design
Shanting Hu, Xiaodong Gu, Masanori Nakahama, and Fumio Koyama
We demonstrate the non-mechanical beam steering and amplifier operation of a vertical cavity surface emitting laser (VCSEL) integrated Bragg reflector waveguide amplifier with a cut-off wavelength detuning design, which enables unidirectional lateral coupling, continuous electrical beam steering, and diffraction-limited divergence angle. We present the modeling of the proposed structure for unidirectional coupling between a seed single-mode VCSEL and slow-light amplifier. We also present the detailed operating characteristics including the near-field and far-field patterns, light/current characteristics, and lasing spectrum. The experimental measurements exhibit a single-mode output of over 8 mW under CW operation, a continuous beam steering range of 16°, and beam divergence below 0.1° as an optical beam scanner. The integrated amplifier length is as small as 0.9 mm, and thus we could expect much higher powers and higher resolution points by increasing the amplifier lengths.
Chinese Optics Letters
  • Publication Date: Sep. 17, 2021
  • Vol.19 Issue, 12 121403 (2021)
Reduced threshold current density of GaN-based green laser diode by applying polarization doping p-cladding layer
Lingrong Jiang, Jianping Liu, Lei Hu, Liqun Zhang, Aiqin Tian, Wei Xiong, Xiaoyu Ren, Siyi Huang, Wei Zhou, Masao Ikeda, and Hui Yang
Chinese Optics Letters
  • Publication Date: Sep. 22, 2021
  • Vol.19 Issue, 12 121404 (2021)
Long-term frequency-stabilized optical frequency comb based on a turnkey Ti:sapphire mode-locked laser
Guang Yang, Haosen Shi, Yuan Yao, Hongfu Yu, Yanyi Jiang, Albrecht Bartels, and Longsheng Ma
We report a long-term frequency-stabilized optical frequency comb at 530–1100 nm based on a turnkey Ti:sapphire mode-locked laser. With the help of a digital controller, turnkey operation is realized for the Ti:sapphire mode-locked laser. Under optimized design of the laser cavity, the laser can be mode-locked over a month, limited by the observation time. The combination of a fast piezo and a slow one inside the Ti:sapphire mode-locked laser allows us to adjust the cavity length with moderate bandwidth and tuning range, enabling robust locking of the repetition rate (fr) to a hydrogen maser. By combining a fast analog feedback to pump current and a slow digital feedback to an intracavity wedge and the pump power of the Ti:sapphire mode-locked laser, the carrier envelope offset frequency (fceo) of the comb is stabilized. We extend the continuous frequency-stabilized time of the Ti:sapphire optical frequency comb to five days. The residual jitters of fr and fceo are 0.08 mHz and 2.5 mHz at 1 s averaging time, respectively, satisfying many applications demanding accuracy and short operation time for optical frequency combs.
Chinese Optics Letters
  • Publication Date: Sep. 17, 2021
  • Vol.19 Issue, 12 121405 (2021)
Influence of annealing temperature on the performance of TiO2/SiO2 nanolaminated films
Yun Cui, Yuanan Zhao, Ge Zhang, Meiping Zhu, Chen Song, Chunxian Tao, Tan Shu, and Jianda Shao
Different laminated structures of TiO2/SiO2 composite film were prepared via atomic layer deposition (ALD) on alumina substrates. The effect of the annealing temperature in the air on the surface morphologies, crystal structures, binding energies, and ingredient content of these films was investigated using X-ray diffraction, field emission scanning electron microscopy, and X-ray photoelectron spectroscopy. Results showed that the binding energy of Ti and Si increased with decrease of the Ti content, and the TiO2/SiO2 nanolaminated films exhibited a complex bonding structure. As the annealing temperature increased, the thickness of the nanolaminated films decreased, and the density and surface roughness increased. An increase in the crystallization temperature was proportional to the SiO2 content in TiO2/SiO2 composite film. The annealing temperature and thin thickness strongly affected the phase structure of the ALD TiO2 thin film. To be specific, the TiO2 thin film transformed into an anatase phase from an amorphous phase after an increase in the annealing temperature from 400°C to 550°C, and the TiO2 film exhibited an anatase phase until the annealing temperature reached 850°C, owing to its extremely small thickness. The annealing process caused the Al ions in the substrate to diffuse into the films and bond with O.
Chinese Optics Letters
  • Publication Date: Sep. 17, 2021
  • Vol.19 Issue, 12 121406 (2021)
VCSEL frequency stabilization for optically pumped magnetometers
Yeguang Yan, Gang Liu, Haixiao Lin, Kaifeng Yin, Kun Wang, and Jixi Lu
Optically pumped magnetometers (OPMs) have developed rapidly in the bio-magnetic measurement field, which requires lasers with stable frequency and intensity for high sensitivity. Herein we stabilize a vertical-cavity surface-emitting laser (VCSEL) without any additional setup except for the parts of an OPM. The linewidth of the absorption spectrum as a frequency reference is broadened to 40 GHz owing to pressure broadening. To enhance performance, the VCSEL injection current and temperature are tuned simultaneously using a closed-loop control system. The experiments reveal that the VCSEL frequency stability achieves 2×10-7 at an average time of 1 s, and the intensity noise is 1×10-6 V/Hz1/2 at 1–100 Hz. This approach is useful for suppressing OPM noise without additional sensor probe parts.
Chinese Optics Letters
  • Publication Date: Nov. 18, 2021
  • Vol.19 Issue, 12 121407 (2021)
Light-matter Interaction
High period frequency LIPSS emerging on 304 stainless steel under the irradiation of femtosecond laser double-pulse trains
Yifei Li, Jie Hu, Wei Liu, Jiangang Yin, and Jiangang Lu
Chinese Optics Letters
  • Publication Date: Sep. 15, 2021
  • Vol.19 Issue, 12 123801 (2021)
Nanophotonics, Metamaterials, and Plasmonics
Multifrequency superscattering pattern shaping
Yao Qin, Jinying Xu, Yineng Liu, and Huanyang Chen
Multifrequency superscattering is a phenomenon in which the scattering cross section from a subwavelength object simultaneously exceeds the single-channel limit at multiple frequency regimes. Here, we achieve simultaneously, within a graphene-coated subwavelength structure, multifrequency superscattering and superscattering shaping with different engineered scattering patterns. It is shown that multimode degenerate resonances at multiple frequency regimes appearing in a graphene composite structure due to the peculiar dispersion can be employed to resonantly overlap electric and magnetic multipoles of various orders, and, as a result, effective multifrequency superscattering with different engineered angular patterns can be obtained. Moreover, the phenomena of multifrequency superscattering have a high tolerance to material losses and some structural variations. Our work should anticipate extensive applications ranging from emission enhancing, energy harvesting, and antenna design with improved sensitivity and accuracy due to multifrequency operation.
Chinese Optics Letters
  • Publication Date: Sep. 02, 2021
  • Vol.19 Issue, 12 123601 (2021)
Strong coupling with absorption and emission features of Ag@Au hollow nanoshells interacting with J-aggregated dye molecules
Tianchen Zhao, Qiang Ma, Yajie Bian, Yuyi Zhang, Yiting Liu, Xiaolei Zhang, Botao Wu, E Wu, Shitao Lou, and Qingyuan Jin
We investigate the strong coupling from 5,5’,6,6’-tetrachloro-1,1’-diethyl-3,3’-di(4-sulfobutyl)-benzimidazolocarbocyanine (TDBC) molecules near pure nano-triangular Ag prisms or Ag@Au hollow nanoshells. When TDBC molecules are deposited on pure Ag nanoprisms or Ag@Au hollow nanoshells with the plasmonic resonance peak, matching very closely with the absorption band of TDBC J-aggregates, obvious Rabi splitting can be observed due to the strong coupling regime. Meanwhile, the photoluminescence intensity decreased with the increasing of the temperature, verifying the decreasing plasmon–exciton coupling interaction in the higher temperature. Our experimental results are coincident with the simulation results calculated by finite-difference time-domain method.
Chinese Optics Letters
  • Publication Date: Sep. 09, 2021
  • Vol.19 Issue, 12 123602 (2021)
Optical Materials
Ultra-fast and low-cost fabrication of transparent paper
Lulin Wei, Jie Li, Haohao Wang, Shuhong Nie, Wenming Su, Dafang Huang, and Mingwei Zhu
Transparent paper is a kind of promising and environmentally friendly material. In this study, we show that transparent paper can be fabricated in an ultra-fast and low-cost way. This low-cost top-down method only takes three steps of cell separation, lignin removal, and cold pressing to obtain a high-quality transparent paper. The fabrication time is further reduced, and the resulted transparent paper shows high transparency up to 90.3%. The application as a substrate material for transparent and flexible electronic devices is demonstrated by emulating the printed circuit on the prepared transparent paper. This top-down method will greatly promote the market-oriented applications of transparent paper as an environment friendly material.
Chinese Optics Letters
  • Publication Date: Sep. 17, 2021
  • Vol.19 Issue, 12 121601 (2021)
Quantum Optics and Quantum Information
Population dynamics of ultra-cold atoms interacting with radiation fields in the presence of inter-atomic collisions
E. Ghasemian, and M. K. Tavassoly
We investigate the dynamics of a system that consists of ultra-cold three-level atoms interacting with radiation fields. We derive the analytical expressions for the population dynamics of the system, particularly, in the presence and absence of nonlinear collisions by considering the rotating wave approximation (RWA). We also reanalyze the dynamics of the system beyond RWA and obtain the state vector of the system to study and compare the time behavior of population inversion. Our results show that the system undergoes two pure quantum phenomena, i.e., the collapse–revival and macroscopic quantum self-trapping due to nonlinear collisional interactions. The occurrence of such phenomena strongly depends on the number of atoms in the system and also the ratio of interaction strengths in the considered system. Finally, we show that the result of the perturbed time evolution operator up to the second-order is in agreement with the numerical solution of the Schrödinger equation. The results presented in the paper may be useful for the design of devices that produce a coherent beam of bosonic atoms known as an atom laser.
Chinese Optics Letters
  • Publication Date: Sep. 09, 2021
  • Vol.19 Issue, 12 122701 (2021)
Airborne quantum key distribution: a review [Invited] | Editors' Pick
Yang Xue, Wei Chen, Shuang Wang, Zhenqiang Yin, Lei Shi, and Zhengfu Han
Remarkable achievements have been witnessed in free-space quantum key distribution (QKD), which acts as an available approach to extend the transmission range of quantum communications. The feasibility of transmitting qubits through the free-space channel with the aid of moving platforms like satellites, aircraft, unmanned aerial vehicles (UAVs) has been verified. In view of the limited working time and resource consumption of the satellite-based QKD and the last-mile challenges of connecting satellite nodes with terrestrial networks, the airborne QKD is expected to provide flexible and relay links for the large-scale integrated network. This paper reviews the recent significant progress of QKD based on aircraft or UAVs, highlights their critical techniques, and prospects the future of airborne quantum communications.
Chinese Optics Letters
  • Publication Date: Nov. 04, 2021
  • Vol.19 Issue, 12 122702 (2021)
Influence of a dielectric decoupling layer on the local electric field and molecular spectroscopy in plasmonic nanocavities: a numerical study
Gong Chen, Jiazhe Zhu, and Xiaoguang Li
Chinese Optics Letters
  • Publication Date: Sep. 17, 2021
  • Vol.19 Issue, 12 123001 (2021)
Ultrafast Optics and Attosecond/High-field Physics
Time-energy analysis of the photoionization process in a double-XUV pulse combined with a few-cycle IR field
Yi Jia, Li Guo, Shilin Hu, Xinyan Jia, Daihe Fan, Ronghua Lu, Shensheng Han, and Jing Chen
We calculate the time-energy distribution (TED) and ionization time distribution (ITD) of photoelectrons emitted by a double-extreme-ultraviolet (XUV) pulse and a two-color XUV-IR pulse using the Wigner distribution-like function based on the strong field approximation. For a double-XUV pulse, besides two identical broad distributions generated by two XUV pulses, many interference fringes resulting from the interference between electrons generated, respectively, by two pulses appear in the TED. After adding an IR field, the TED intuitively exhibits the effect of the IR field on the electron dynamics. The ITDs during two XUV pulses are no longer the same and show the different changes for the different two-color fields, the origin of which is attributed to the change of the electric field induced by the IR field. Our analysis shows that the emission time of electrons ionized during two XUV pulses mainly depends on the electric field of the combined XUV pulse and IR pulse.
Chinese Optics Letters
  • Publication Date: Aug. 10, 2021
  • Vol.19 Issue, 12 123201 (2021)
Wave mixing and high-harmonic generation enhancement by a two-color field driven dielectric metasurface [Invited]
Weifeng Yang, Yichong Lin, Xueyi Chen, Yuxuan Xu, Hongdan Zhang, Marcelo Ciappina, and Xiaohong Song
High-harmonic generation in metasurfaces, driven by strong laser fields, has been widely studied. Compared to plasma, all-dielectric nanoscale metasurfaces possess larger nonlinearity response and higher damage threshold. Additionally, it can strongly localize the driven field, greatly enhancing its peak amplitude. In this work, we adopt a Fano resonant micro-nano structure with transmission peaks at different wavelengths and explore its nonlinear response by both single and two-color pump fields. Compared to the high-order harmonics induced by the first resonant wavelength, the intensity of the high-harmonic radiation results is enhanced by one order of magnitude, when the metasurface is driven by various resonant and non-resonant wavelength combinations of a two-color field.
Chinese Optics Letters
  • Publication Date: Oct. 18, 2021
  • Vol.19 Issue, 12 123202 (2021)
Nanophotonics, Metamaterials, and Plasmonics
Metallic nanoparticles/graphene-molecules hybrid system-based active biosensor
Walid Aroua
The strong coupling between vibrational modes of molecules and surface plasmon resonance (SPR) modes in graphene makes them an ideal platform for biosensor techniques. In this paper, a new optical biosensor for molecule detection based on silver metallic nanoparticles (MNPs) and graphene/gold MNPs in a terahertz frequency range is achieved. It is established that the nonlinear electrical properties of graphene can play a major role in realizing a biosensor for molecule detection. The performance parameters of the proposed device are reported with respect to the chemical potential μ of graphene, noting that the sensitivity of our device passes from 255 nm/RIU (nanometers/refractive index unit) for μ=1.21 eV to 2753 nm/RIU for μ=0.21 eV. Finally, this structure exhibits an optical sensing region that can be adjusted to meet the requirements of optical detection.
Chinese Optics Letters
  • Publication Date: Sep. 23, 2021
  • Vol.19 Issue, 12 123603 (2021)