- 标题
- 摘要
- 关键词
- 实验方案
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Large-Dynamic Frequency Response Measurement for Broadband Electro-Optic Phase Modulators
摘要： A novel method for characterizing the frequency responses of broadband electro-optic phase modulators (PMs) by employing stimulated Brillouin scattering (SBS) is proposed and experimentally demonstrated. In the proposed method, the SBS amplifies the +1st-order sideband and attenuates the -1st-order sideband of the phase-modulated signal from a PM under test. Thereby, the phase-modulated signal is converted into an optical single-sideband (OSSB) modulation signal. After square-law photodetection, the overall frequency responses are obtained. Removing the frequency responses of the SBS gain and the photodetector (PD) from the overall responses, the responses of the PM are thus achieved. Benefitting from the amplification of the SBS, the proposed method possesses a large dynamic range. Sub-Hz resolution and broadband measurement range are also achievable. A commercial broadband PM is experimentally characterized from 10 MHz to 50 GHz with a resolution of 5 MHz. According to the amplification of the SBS, the dynamic range is enhanced by 17.74 dB. The measurement result is verified by the conventional method utilizing optical spectrum analysis.
关键词： stimulated Brillouin scattering,Electrooptic modulation,Phase modulation,microwave photonics,optical variables measurement
更新于2025-11-28 14:24:03
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100?GHz free spectral range-tunable multi-wavelength fiber laser using single–multi–single mode fiber interferometer
摘要： Six single–multi–single (SMS) mode fiber-based Mach–Zehnder Interferometers (MZI) with different spooling radii are demonstrated as spatial mode filtering elements for multi-wavelength laser generation. Free spectral range (FSR) tuning of the multi-wavelength output generated is realized by alternating between the six MZIs, which have different macro-bending losses. Additional FSR tuning is also realized by changing the spooling radius of the two-mode step index fiber section within the MZI setups from 80 mm to 30 mm, giving an FSR tuning range of 0.89–0.99 nm. All generated multi-wavelength outputs show high stability over a test period of 100 min. The proposed multi-wavelength lasers are highly suitable for various microwave photonics applications the field of such as microwave signal source generation and microwave photonic filtering.
关键词： free spectral range tuning,Mach–Zehnder Interferometer,microwave photonics,multi-wavelength fiber laser
更新于2025-11-28 14:23:57
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Active ring resonance cavity assisted single-mode all-optical microwave oscillator
摘要： A pure optical microwave oscillator with single mode oscillation is proposed and demonstrated. This system has no any electrical microwave devices as well as electro-optic (E/O) and opto-electronic (O/E) conversion. The oscillation frequency is chosen by Brillouin-selective sideband amplification, and the optical envelope detection and feedback modulation are implemented by a semiconductor optical amplifier (SOA). As a high-Q tunable optical comb filter, an active ring resonance cavity (ARRC) is employed to select one oscillation mode within the Brillouin gain region, and consequently a single mode oscillation signal can be generated. In the experiment, a single mode photonic microwave signal with frequency of 10.83 GHz and side-mode suppression ratio of 48 dB is obtained. The measured phase noise is ?88 dBc/Hz@10 kHz. In addition, the tunability is also demonstrated by adjusting the wavelength of the light source.
关键词： Microwave photonics,SBS,All-optical microwave oscillator
更新于2025-11-28 14:23:57
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Hot wire chemical vapor deposition for silicon photonics: An emerging industrial application opportunity
摘要： In this work different silicon photonic devices, including straight waveguides, multi-mode interference devices and Mach-Zehnder interferometers, were fabricated and characterized on hot-wire chemical vapor deposition (HWCVD) silicon nitride (SiN) layers deposited at temperatures below 350 °C. These layers presented a hydrogen concentration of 13.1%, which is lower than that achieved with plasma enhanced chemical vapor deposition at these deposition temperatures. The lowest reported optical propagation losses of 6.1 dB/cm and 5.7 dB/cm, 1550 nm and 1310 respectively, for straight SiN waveguides prepared by HWCVD was measured. We demonstrated that silicon nitride SiN, prepared using HWCVD, is a viable material for silicon photonics fabrication.
关键词： Multimode interferometer,Silicon photonics waveguides,Silicon photonics,Hot wire chemical vapor deposition,Silicon nitride,Mach-Zehnder interferometer
更新于2025-11-21 11:20:42
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Beta-lead oxide quantum dot (β-PbO QD)/polystyrene (PS) composite films and their applications in ultrafast photonics
摘要： Polymer composite films, particularly those based on polymers and layered nanomaterials, are attractive materials for exploiting the properties of multiple materials for applications in electronics and photonics. In this work, a beta-lead oxide quantum dot (β-PbO QD)/polystyrene (PS) composite film is successfully fabricated by a solution blending method. The β-PbO QDs are well-distributed within a β-PbO QD/PS composite film and the composite film is transparent and flexible. Owing to the almost complete insolubility of both β-PbO QDs and PS, the as-fabricated β-PbO QD/PS composite film holds the nonlinear photonic response from 540 nm to 1060 nm under complete water immersion, confirming its excellent stability to high humidity. Additionally, the β-PbO QD/PS composite film exhibits a considerable capacity for optical modulation owing to a strong nonlinear absorption coefficient compared with those of other two-dimensional (2D) materials. On the basis of a home-made β-PbO QD/PS composite film saturable absorber, stable mode-locked pulses at 1060 nm are generated under humid conditions. It is anticipated that the β-PbO QD/PS composite films enable the exploitation of new waterproof, flexible photonic devices based on functional 2D materials and polymers.
关键词： composite films,mode-locked pulses,ultrafast photonics,polystyrene,nonlinear absorption,beta-lead oxide quantum dot
更新于2025-11-19 16:56:42
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Low-loss and broadband non-volatile phase-change directional coupler switches
摘要： An optical equivalent of the field-programmable gate array (FPGA) is of great interest to large-scale photonic integrated circuits. Previous programmable photonic devices relying on the weak, volatile thermo-optic or electro-optic effect usually suffer from a large footprint and high energy consumption. Phase change materials (PCMs) offer a promising solution due to the large non-volatile change in the refractive index upon phase transition. However, the large optical loss in PCMs poses a serious problem. Here, by exploiting an asymmetric directional coupler design, we demonstrate non-volatile PCM-clad silicon photonic 1 × 2 and 2 × 2 switches with a low insertion loss of ~1 dB and a compact coupling length of ~30 μm while maintaining a small crosstalk less than ?10 dB over a bandwidth of 30 nm. The reported optical switches will function as the building blocks of the meshes in the optical FPGAs for applications such as optical interconnects, neuromorphic computing, quantum computing, and microwave photonics.
关键词： Silicon photonics,Non-volatile,Optical switches,Phase-change materials,Reconfigurable photonics,Integrated photonic devices
更新于2025-09-23 15:23:52
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Experimental Realization of Multiple Topological Edge States in a 1D Photonic Lattice
摘要： Topological photonic systems offer light transport that is robust against defects and disorder, promising a new generation of chip-scale photonic devices and facilitating energy-efficient on-chip information routing and processing. However, present quasi one dimensional (1D) designs, such as the Su–Schrieffer–Heeger and Rice–Mele models, support only a limited number of nontrivial phases due to restrictions on dispersion band engineering. Here, a flexible topological photonic lattice on a silicon photonic platform is experimentally demonstrated that realizes multiple topologically nontrivial dispersion bands. By suitably setting the couplings between the 1D waveguides, different lattices can exhibit the transition between multiple different topological phases and allow the independent realization of the corresponding edge states. Heterodyne measurements clearly reveal the ultrafast transport dynamics of the edge states in different phases at a femtosecond scale, validating the designed topological features. The study equips topological models with enriched edge dynamics and considerably expands the scope to engineer unique topological features into photonic, acoustic, and atomic systems.
关键词： multi-topological numbers,topological photonics,topological edge states,ultra-fast heterodyne imaging
更新于2025-09-23 15:23:52
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Real-time adaptive optical self-interference cancellation system for in-band full-duplex transmission
摘要： A real-time adaptive optical self-interference cancellation (RTA-OSIC) system is proposed and demonstrated for in-band full-duplex transmission. The RTA-OSIC system is controlled automatically by adaptive algorithm running on a real-time microcontroller STM32. Modified Hooke-Jeeves (MHJ) algorithm is proposed to search the optimal optical parameters more rapidly. Experimental results show that the MHJ algorithm requires 15-25 samples to find the optimal point. The RTA-OSIC system achieves more than 22 dB cancellation depth within 0-700MHz frequency band. Compared with the existing adaptive OSIC system which uses the Nelder–Mead Simplex algorithm, there are 60% less samples for our RTA-OSIC system with MHJ algorithm.
关键词： self-interference cancellation,Modified Hooke-Jeeves (MHJ) algorithm,microwave photonics,real-time adaptation
更新于2025-09-23 15:23:52
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Asymmetric Diarylethenes with Oxidized 2-Alkylbenzothiophen-3-yl Units: Chemistry, Fluorescence, and Photoswitching
摘要： Reversibly photoswitchable diarylethenes (DAEs) with fluorescent closed forms are applied in biology- and material science-related super-resolution microscopy. Yet, their full photoswitchable capacities remain unrevealed and unexplored. Due to limitations in synthesis, only 1,2-[bis-(2-ethyl-1-benzothiophene-1,1-dioxide-3-yl)]perfluorocyclopentenes with two identical or very similar aryl groups attached to C-6 and C-6′ have been prepared so far. DAEs with increased Stokes shifts related to asymmetric structures and the presence of 'push–pull' substituents are introduced in the present study, and their switching power is studied. The new 'simplified' asymmetric DAEs possess higher cycloreversion quantum yields, but lower emission efficiencies than their known analogs with extended π-conjugation paths. Fatigue resistance in organic (acetonitrile and methanol) and aqueous solvents is studied, and the performance in reversible saturable optical fluorescence transition (RESOLFT) microscopy is evaluated. The push–pull structures show an outstanding increase in fatigue resistance, compared with a reference (H/H) diarylethene. Fatigue resistances on the order of thousands of cycles have been observed in acetonitrile solutions without exclusion of air oxygen. The structure–property relationships and facile preparation procedures enable rational design of DAEs applicable as photoswitchable fluorescent probes. A new setup and methodology for measuring switching performance of fluorescent DAEs are introduced.
关键词： photoluminescence,photonics,photochemistry,structure–property relationships
更新于2025-09-23 15:23:52
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Optical coherence tomography—A review of the opportunities and challenges for postharvest quality evaluation
摘要： Optical Coherence Tomography (OCT) is an established non-destructive and contactless photonic technique which has now been shown to be suitable for monitoring the near-surface internal structure of tissues in stored fruit and vegetables. Such real-time cross-sectional imaging allows for better visualisation and understanding of the temporal changes in internal structure. However, despite these advantages, problems persist around the trade-off between imaging resolution and penetration depth, image analysis and data processing, and the applicability of in situ studies outside of the laboratory setting. This review summarises previous postharvest OCT research and assesses resulting mechanistic outcomes, and future potential.
关键词： Microstructure,Non-destructive,Imaging,Photonics,Fresh produce
更新于2025-09-23 15:23:52