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Low-resolution Kramers-Kronig detection system with error-feedback noise shaping

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Science China(Information Sciences) 2024年第5期67卷 259-269页

作者： Xiangyong DONG Zhenming YU Hongyu HUANG Kaixuan SUN Kun XU State Key Laboratory of Information photonics and Optical Communications Beijing University of Posts and Telecommunications

In this paper, we investigated the effects of error-feedback noise shaping(EFNS) on a lowresolution Kramers-Kronig(KK) detection system for the first time. Both 16-ary quadrature amplitude modulation(16-QAM) and 64-ary quadrature amplitude modulation(64-QAM) were considered in the experiment. The carrier tone was added on the transmitter side using the virtual carrier-assisted single sideband(VCA-SSB) method to meet the minimum phase(MP) condition. Under the MP condition, KK detection only needs the intensity of the optical signal to be detected by one photodiode(PD) to retrieve the phase information. However, the virtual carrier tone increases the carrier-to-signal power ratio(CSPR), which results in a high peak-to-average power ratio(PAPR) at the transmitter, causing an increase in quantization noise. To mitigate quantization noise in the low-resolution KK detection system, EFNS was applied. The application of EFNS increased the optimal CSPR of the KK detection system and improved receiver sensitivity. Using a 4-bit DAC and the EFNS, 80 km transmission was achieved in the 60-Gbit/s 64-QAM KK detection system.

关键词： optical fiber communications Kramers-Kronig receiver error-feedback noise shaping quantization noise carrier-to-signal power ratio

Time-resolution enhanced multi-path OTD measurement using an adaptive filter based incoherent OFDR

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Chinese Optics Letters 2024年第1期22卷 153-158页

作者：王立晗任凌云王祥传潘时龙 National Key Laboratory of Microwave photonics Nanjing University of Aeronautics and AstronauticsNanjing 210016China

High accuracy and time resolution optical transfer delay(OTD)measurement is highly desired in many multi-path applications,such as optical true-time-delay-based array systems and distributed optical ***,the time resolution is usually limited by the frequency range of the probe signal in frequency-multiplexed OTD measurement ***,we proposed a time-resolution enhanced OTD measurement method based on incoherent optical frequency domain reflectometry(I-OFDR),where an adaptive filter is designed to suppress the spectral leakage from other paths to break the resolution limitation.A weighted least square(WLS)cost function is first established,and then an iteration approach is used to minimize the cost ***,the appropriate filter parameter is obtained according to the convergence *** a proof-of-concept experiment,the time-domain response of two optical links with a length difference of 900 ps is successfully estimated by applying a probe signal with a bandwidth of 400 *** time resolution is improved by 2.78times compared to the theoretical resolution limit of the inverse discrete Fourier transform(iDFT)*** addition,the OTD measurement error is below±0.8 *** proposed algorithm provides a novel way to improve the measurement resolution without applying a probe signal with a large bandwidth,avoiding measurement errors induced by the dispersion effect.

关键词： optical transfer delay measurement time resolution enhancement incoherent OFDR adaptive filtering

Wide-angle digital holography with aliasing-free recording

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photonics Research 2024年第5期12卷 1098-1106页

作者： RAFAL KUKOLOWICZ IZABELA GEREJ TOMASZ KOZACKI Institute of Micromechanics and photonics Warsaw University of Technology02-525 WarsawPoland

High-quality wide-angle holographic content is at the heart of the success of near-eye display *** work proposes the first digital holographic(DH)system enabling recording wide-angle scenes assembled from objects larger than the setup field of view(FOV),which can be directly replayed without 3D deformation in the near-eye *** hologram formation in the DH system comprises free space propagation and Fourier transform(FT),which are connected by a rectangular ***,the object wave propagates in free space to the rectangular ***,the band-limited wavefield is propagated through the single lens toward the camera *** rectangular aperture can take two sizes,depending on which DH operates in off-axis or phase-shifting recording *** integral part of the DH solution is a numerical reconstruction algorithm consisting of two elements:fringe processing for object wave recovery and wide-angle propagation to the object *** second element simulates propagation through both parts of the experimental *** free space part is a space-limited angular spectrum compact space algorithm,while for propagation through the lens,the piecewise FT algorithm with Petzval curvature compensation is *** the experimental part of the paper,we present the wide-angle DH system with FOV25°×19°,which allows high-quality recording and reconstruction of large complex scenes.

关键词： recording angle holographic

Optical pulse repetition rate division using an optoelectronic oscillator

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Chinese Optics Letters 2024年第4期22卷 125-129页

作者：李平邵琨麟张亚梅潘时龙 National Key Laboratory of Microwave photonics Nanjing University of Aeronautics and AstronauticsNanjing 210016China

An approach for frequency division of an optical pulse train(OPT) based on an optoelectronic oscillator(OEO) is proposed and experimentally demonstrated. When the OPT is injected into the OEO, a microwave signal with a frequency equaling fractional multiples of the repetition rate of the OPT is generated. This signal is then fed back to the OEO, maintaining its oscillation, while simultaneously serving as the control signal of a Mach–Zehnder modulator(MZM) in the OEO. The MZM acts as an optical switch, permitting specific pulses to pass through while blocking others. As a result, the repetition rate of the OPT is manipulated. A proof-of-concept experiment is carried out. Frequency division factors of 2 and 3 are successfully achieved. The phase noises of the OPT before and after the frequency division are investigated. Compared to previously reported systems, no external microwave source and sophisticated synchronization structure are needed.

关键词： frequency division optoelectronic oscillator mode-locked laser microwave photonics

Optimizing depth of field in 3D light-field display by analyzing and controlling light-beam divergence angle

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Chinese Optics Letters 2024年第1期22卷 14-20页

作者：于迅博王一平高鑫李涵宇刘柯新颜玢玢桑新柱 State Key Laboratory of Information photonics and Optical Communications Beijing University of Posts and Telecommunications(BUPT)Beijing 100876China

A concept of divergence angle of light beams(DALB)is proposed to analyze the depth of field(DOF)of a 3D light-field display *** mathematical model between DOF and DALB is established,and the conclusion that DOF and DALB are inversely proportional is *** reduce DALB and generate clear depth perception,a triple composite aspheric lens structure with a viewing angle of 100°is designed and experimentally *** DALB-constrained 3D light-field display system significantly improves the clarity of 3D images and also performs well in imaging at a 3D scene with a DOF over 30 cm.

关键词： 3D light-field display depth of field divergence angle of light beams compound lens

Free-moving-state microscopic imaging of cerebral oxygenation and hemodynamics with a photoacoustic fiberscope

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Light(Science & Applications) 2024年第1期13卷 33-46页

作者： Xiaoxuan Zhong Yizhi Liang Xiaoyu Wang Haoying Lan Xue Bai Long Jin Bai-Ou Guan Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications Institute of Photonics TechnologyJinan UniversityGuangzhou510632China

We report the development of a head-mounted photoacoustic fiberscope for cerebral imaging in a freely behaving *** 4.5-gram imaging probe has a 9-µm lateral resolution and 0.2-Hz frame rate over a 1.2-mm wide *** probe can continuously monitor cerebral oxygenation and hemodynamic responses at single-vessel resolution,showing significantly different cerebrovascular responses to external stimuli under anesthesia and in the freely moving *** example,when subjected to high-concentration CO_(2) respiration,enhanced oxygenation to compensate for hypercapnia can be visualized due to cerebral regulation in the freely moving *** studies exhibit significantly weakened compensation capabilities in obese *** new imaging modality can be used for investigating both normal and pathological cerebrovascular functions and shows great promise for studying cerebral activity,disorders and their treatments.

关键词： cerebral anesthesia moving

Inverse-designed Jones matrix metasurfaces for high-performance meta-polarizers

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Chinese Optics Letters 2024年第2期22卷 192-199页

作者：王志强李枫竣邓倩媚万舟李向平邓子岚 Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications Institute of Photonics TechnologyJinan UniversityGuangzhou 510632China

Polarizers have always been an important optical component for optical engineering and have played an indispensable part of polarization imaging *** polarizers provide an excellent platform to achieve miniaturization,high resolution,and low cost of polarization imaging ***,we proposed freeform metasurface polarizers derived by adjoint-based inverse design of a full-Jones matrix with gradient-descent *** designed multiple freeform polarizers with different filtered states of polarization(SOPs),including circular polarizers,elliptical polarizers,and linear polarizers that could cover the full Poincaré*** that near-unitary polarization dichroism and the ultrahigh polarization extinction ratio(ER)reaching 50 d B were achieved for optimized circular *** multiple freeform polarizers with filtered polarization state locating at four vertices of an inscribed regular tetrahedron of the Poincarésphere are designed to form a full-Stokes parameters micropolarizer *** work provides a novel approach,we believe,for the design of meta-polarizers that may have potential applications in polarization imaging,polarization detection,and communication.

关键词： metasurface inverse design Jones matrix polarization imaging

Fabrication of Mie-resonant silicon nanoparticles using laser annealing for surface-enhanced fluorescence spectroscopy

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Microsystems & Nanoengineering 2024年第2期10卷 133-141页

作者： Tatsuya Fukuta Ryo Kato Takuo Tanaka Taka-aki Yano Institute of Post-LED photonics Tokushima University2-1 Minami-JosanjimaTokushima770-8506Japan Innovative Photon Manipulation Research Team RIKEN Center for Advanced PhotonicsWakoSaitama351-0198Japan Metamaterials Laboratory RIKEN Cluster for Pioneering ResearchWakoSaitama351-0109Japan

Silicon nanostructures with unique Mie resonances have garnered considerable attention in the field of ***,we present a simple and efficient method for the fabrication of silicon(Si)nanoparticle substrates using continuous-wave(CW)laser *** resulting silicon nanoparticles exhibit Mie resonances in the visible region,and their resonant wavelengths can be precisely ***,laser-annealed silicon nanoparticle substrates show a 60-fold enhancement in *** tunable and fluorescence-enhancing silicon nanoparticle platform has tremendous potential for highly sensitive fluorescence sensing and biomedical imaging applications.

关键词： nanoparticles annealing resonant

Joint modulation format identification and OSNR monitoring based on Stokes vector distribution features for digital coherent optical receivers

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Chinese Optics Letters 2024年第5期22卷 22-28页

作者：蒲正宇蒋林闫连山易安林何海军潘炜罗斌 Center for Information photonics&Communications School of Information Science and TechnologySouthwest Jiaotong UniversityChengdu 611756China

For joint modulation format identification(MFI)and optical signal-to-noise ratio(OSNR)monitoring,a simple and intelligent optical communication performance monitoring method is proposed,and the feasibility is demonstrated by digital coherent optical communication *** experiment results show that for all modulation formats,including 28 GBaud polarization division multiplexing(PDM)QPSK/8-QAM/16-QAM/64-QAM,100%MFI accuracies are achieved even at OSNR values lower than the corresponding theoretical 20%forward error correction limit,as well as the high accuracies for OSNR ***,the proposed scheme has a reasonable monitoring level when chromatic dispersion and fiber nonlinear effects are varied.

关键词： coherent communication optical performance monitoring deep neural network