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Optical microfiber-based ultrafast fiber lasers
摘要： Optical microfibers drawn from conventional fibers have attracted considerable interests and have found many novel applications. Here, we review recent advances in ultrafast fiber lasers based on optical microfibers. Starting with characteristics and fabrication of optical microfibers, which are closely related to ultrafast fiber lasers, we show that characteristics of large portion of evanescent field, tailorable dispersion, high optical nonlinearity, very low optical loss and full compatibility with conventional fibers are greatly beneficial to novel ultrafast fiber lasers. We then highlight recent works on ultrafast fiber lasers based on optical microfibers in terms of fast saturable absorbers made from optical microfiber-supported nanomaterials, dispersion management and high optical nonlinearity, as well as some other novel ultrafast fiber lasers. Finally, we briefly discuss future opportunities for optical microfiber-based ultrafast fiber lasers, such as high-order dispersion management, nonlinearity management and applications for sensing and measurement.
关键词： Dispersion management,Saturable absorbers,Ultrafast fiber lasers,Optical microfibers,Optical nonlinearity
更新于2025-09-12 10:27:22
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An On‐Chip Quad‐Wavelength Pyroelectric Sensor for Spectroscopic Infrared Sensing
摘要： Merging photonic structures and optoelectronic sensors into a single chip may yield a sensor-on-chip spectroscopic device that can measure the spectrum of matter. In this work, an on-chip concurrent multiwavelength infrared (IR) sensor, which consists of a set of narrowband wavelength-selective plasmonic perfect absorbers combined with pyroelectric sensors, where the response of each pyroelectric sensor is boosted only at the resonance of the nanostructured absorber, is proposed and realized. The proposed absorber, which is based on Wood’s anomaly absorption from a 2D plasmonic square lattice, shows a narrowband polarization-independent resonance (quality factor – Q of 73) with a nearly perfect absorptivity as high as 0.99 at normal incidence. The fabricated quad-wavelength IR sensors exhibit four different narrowband spectral responses at normal incidence following the predesigned resonances in the mid-wavelength infrared region that corresponds to the atmospheric window. The device can be applied for practical spectroscopic applications such as nondispersive IR sensors, IR chemical imaging devices, pyrometers, and spectroscopic thermography imaging.
关键词： wavelength-selective infrared sensors,perfect absorbers,pyroelectric sensors,on-chip sensors,plasmonic metamaterials
更新于2025-09-11 14:15:04
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A broadband terahertz metamaterial absorber enabled by the simple design of a rectangular-shaped resonator with an elongated slot
摘要： Broadband metamaterial absorbers are of critical importance in practical applications, but their obtainment approaches are quite complex at present. We demonstrate here that a fairly simple structure design formed by a rectangular-shaped resonator having an elongated slot can be utilized to achieve a broadband absorption response at terahertz frequencies. More than 50% absorption in a continuous frequency range of 1.62 THz (with a central frequency of 2.05 THz) can be gained, and its relative absorption bandwidth is 79.02%, which is superior to that of previous broadband absorption devices. The basic principle of the broadband absorption originates from the superposition of four di?erent but narrowly separated resonance peaks that resulted from di?erent response positions of the suggested resonator. Results further reveal that the broadband terahertz absorption performance (or its four resonance peaks) can be controlled by the resonator dimensions. The suggested method can provide a new type of design strategy to realize broadband integrated terahertz absorption devices.
关键词： resonance peaks,rectangular-shaped resonator,elongated slot,broadband metamaterial absorbers,terahertz frequencies
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Comparison of Different Mode-Locking Methods in the Ho-Doped Fiber Laser
摘要： Ultrafast fiber sources operating in the spectral range of 2-3 μm have attracted attention due to a number of possible applications, e.g. for perspective communications, gas sensing, nonlinear frequency conversion, and medicine. Holmium-doped fibers (HDF) are commonly used as a gain medium for 2 μm lasers due to their broad gain spectrum, extending from 2 to 2.2 μm. Most of the presented works on Ho-doped ultrafast fiber lasers have concentrated on mode-locking regime initiated by saturable absorbers (SAs) such as carbon nanotubes (CNT) [1], graphene [2], black phosphorus [3], and semiconductor saturable absorber mirrors (SESAMs) [4]. The mode-locking regime in an all-fiber Holmium laser also has been obtained by nonlinear polarization evolution (NPE) [5]. In this work, we demonstrate a comparison of different methods of mode-locking obtaining in one Ho-doped fiber laser cavity under the same condition and analyze the parameters of the obtained pulsed radiation. We have compared such methods as NPE and two hybrid regimes: NPE+single walled CNTs [6, 7], NPE+graphene. The optical scheme of the experimental setup is shown in Fig. 1. Ho-doped fiber laser was pumped through a wavelength division multiplexer (WDM) by a custom-made 1125 nm Yb-doped fiber laser delivering up to 8 W of continuous wave power. The cavity of the laser was formed by active Ho-doped fiber (≈ 6 m) and single-mode fiber (≈ 8 m). A fiber polarizer and a pair of polarization controllers were added into the laser cavity to obtain NPE mode-locking. The SWCNTs or graphene SA were fixed between two optical FC/APC-connectors to realize hybrid mode-locking. The isolator (ISO) was used to obtain unidirectional lasing. The pulse signal was coupled out from the laser cavity using a 9/1 fiber coupler (90% coupler output was used as the output of the laser). The total intracavity dispersion was estimated as about –1.5 ps2. Stable pulsed lasing by NPE was obtained at a pump power of 3 W, whereas in the case of NPE+SWCNTs mode-locking lasing threshold increased up to 3.3 W of pump power. The average lasing power in the NPE and NPE+SWCNTs regimes was 6.4 and 4.7 mW, respectively. Fig. 2 shows the emission spectra of a pulsed Ho-doped fiber laser operating in different regimes. As can be seen, the spectra have different values of the central wavelength and full width at half maximum (FWHM). Fig. 3 shows the autocorrelation traces. The pulse width in both cases did not exceed 1.5 ps. The pulse energies in the NPE mode-locking and NPE+SWCNTs mode-locking regimes were 0.4 and 0.3 nJ, respectively. The pulse repetition frequency was 14.9 MHz. The signal-to-noise ratio in the case of NPE+SWCNTs mode-locking was 3 dB better than that implemented under conditions of NPE mode-locking.
关键词： saturable absorbers,mode-locking,hybrid regimes,Ho-doped fiber laser,nonlinear polarization evolution
更新于2025-09-11 14:15:04
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Stable all-fiber passively Q-switched erbium-doped fiber laser based on plasmonic Zn doped CuGaO <sub/>2</sub> nanoplates
摘要： In this letter, we synthesized p-type Zn doped hexagonal CuGaO2 (CGZO) nanoplates (NPs) by hydrothermal reaction and utilized the nonlinear optical properties of these plasmonic NPs to realized stable passively Q-switched erbium-doped fiber laser output. We achieved tunable saturable absorbers (SAs) by changing the doping ratio of CGZO NPs. With the increase of the doping ratio, pulse duration decreases from 2.532 μs to 2.276 μs and the optical-optical conversion efficiency of the Q-switched laser increases from 1.36% to 1.70%. Our result suggests that CGZO is promising to allow tunable SAs to generate passively Q-switched fiber lasers.
关键词： Q-switched fiber laser,plasmonic Zn doped CuGaO2 nanoplates,saturable absorbers,nonlinear optical properties
更新于2025-09-11 14:15:04
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Organic‐Inorganic Copper (II) Based Perovskites: A Benign Approach towards Low‐Toxic and Water Stable Light Absorbers for Photovoltaic Applications
摘要： Despite Organometal halide perovskites specially lead (Pb) based have been emerged as the most promising light absorber for thin film solar cells. Although, the power conversion efficiencies for Pb based perovskite solar cells have gone from 3% to a certified efficiency of 23%. However, there are some serious issues need to be addressed to commercialize this perovskite solar cells are the presence of Pb and its moisture sensitivity. Herein, we report a highly stable organic-inorganic copper (II) based perovskites as alternative to the existing Pb perovskites by introducing a novel arcitechture of mesoscopic perovskite solar cells. Apart from remarkable good open circuit voltage of 370mV with a power conversion efficiency of 0.63%, the present PSC shows excellent water stability and their optoelectronic properties for photovoltaic applications.
关键词： less toxic,solar cells,Water stable,light absorbers,Pb free perovskites
更新于2025-09-11 14:15:04
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Mode-Locked Er-Doped Fiber Laser by Using MoS2/SiO2 Saturable Absorber
摘要： The two-dimensional (2D) layered material MoS2 has attracted numerous attentions for electronics and optoelectronics applications. In this work, a novel type of MoS2-doped sol-gel glass composite material is prepared. The nonlinear optical properties of prepared MoS2/SiO2 composite material are measured with modulation depth (ΔT) of 3.5% and saturable intensity (Isat) of 20.15 MW/cm2. The optical damage threshold is 3.46 J/cm2. Using the MoS2/SiO2 composite material as saturable absorber (SA), a passive mode-locked Er-doped fiber (EDF) laser is realized. Stable conventional soliton mode-locking pulses are successfully generated with a pulse width of 780 fs at the pump power of 90 mW. In the pump power range of 100–600 mW, another stable mode-locking operation is obtained. The pulse width is 1.21 ps and the maximum output power is 5.11 mW. The results indicate that MoS2/SiO2 composite materials could offer a new way for optical applications.
关键词： Nonlinear optical materials,Saturable absorbers,Transition metal dichalcogenides
更新于2025-09-11 14:15:04
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Damage analysis of a perfect broadband absorber by a femtosecond laser
摘要： Plasmonic metamaterial absorbers are particularly important in different applications such as photodetectors, microbolometers and solar cells. in this paper, we propose a tungsten boride (WB, a refractory ceramic) based broadband metamaterial absorber whose optical properties is numerically analyzed and experimentally characterized. We have also analyzed the damage characteristics of this absorber using a femtosecond laser and compared with an ordinary Au metamaterial absorber. We observe that WB has almost the double absorption bandwidth with absorption more than 90% over the spectral range of 950 to 1400 nm when compared with the Au counterpart. Furthermore, we show that Au metamaterial is damaged at the power of around 36.4 mW whereas WB metamaterial is not damaged at that power (WB has high tammann temperature than Au)-however the atom of WB material was knocked off by the bombardment of a femtosecond laser.
关键词： tungsten boride,femtosecond laser,broadband absorption,damage analysis,Plasmonic metamaterial absorbers
更新于2025-09-11 14:15:04
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Research on Measurement Uncertainty of Absorption Cross Section in a Reverberation Chamber
摘要： The absorption cross section (ACS) of absorbers are measured in a reverberation chamber and the relative uncertainty of measurements is calculated. The ACS is calculated by a time-domain method at frequencies in the range 1~3GHz. The average relative uncertainty of the ACS over the frequency range in eight different configurations of absorbers and antennas, which shows good experimental stability, is 0.02 by the measurements.
关键词： Time-domain Method,Absorbers,Reverberation Chamber,Measurement Uncertainty,Absorption Cross Section
更新于2025-09-10 09:29:36
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[Springer Tracts in Modern Physics] Parity-time Symmetry and Its Applications Volume 280 || PT-Symmetry and Non-Hermitian Wave Transport in Microwaves and RF Circuits
摘要： Many novel concepts in PT -symmetric wave transport were initially explored and demonstrated in the conceptually simpler and experimentally more accessible framework of active electronic circuits. These include eigenmode analysis and spatio-temporal dynamics of the stored energy in static and in periodically driven (Floquet) PT -symmetric circuits, and PT -symmetric scattering in both the linear and nonlinear regime. We review several of these advances – often stretching the borders of investigation to the most general area of non-Hermitian wave transport where concepts like coherent perfect absorbers, gain-induced lasing shut-down, and asymmetric transport are naturally emerging.
关键词： coherent perfect absorbers,RF circuits,asymmetric transport,microwaves,PT-symmetry,non-Hermitian wave transport,gain-induced lasing shut-down
更新于2025-09-10 09:29:36