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Dispersion independent mode-locked erbium-doped fiber laser with a chirped fiber Bragg grating
摘要： We propose and demonstrate a dispersion-independent erbium-doped mode-locked fiber laser by incorporating a chirped fiber Bragg grating (CFBG) into the laser cavity. Our experimental results show that the fiber laser has similar output characteristics, no matter which section of the CFBG is connected to the laser cavity through a circulator, i.e., opposite dispersion is introduced into the laser cavity. Dispersion independent feature is attributed to the relatively large nonlinearity of the laser cavity with certain bandwidth. This enriches the laser dynamics and provides a new idea for the design of new lasers.
关键词： mode-locked,fiber laser.,Chirped fiber Bragg grating
更新于2025-11-28 14:24:03
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[IEEE 2018 IEEE 7th International Conference on Photonics (ICP) - Kuah (2018.4.9-2018.4.11)] 2018 IEEE 7th International Conference on Photonics (ICP) - Experimental Analyses of Confined Thermal Effect on Chirped Fiber Bragg Grating
摘要： Chirped fiber Bragg gratings (C-FBGs) have found various important applications in the field of optical communication and sensing. These applications manipulated the distinctive refractive index structures, wherein its spectral response is modifiable by variation of its local physical property. This paper specifically analyzes the effect of localized thermal effect on C-FBG using a micro-size heating element to achieve confined heating. The results reveal that localized thermal effect will produce a phase-shift dip in the spectrum, whose depth, linewidth and center wavelength are correlated to the magnitude and position of the applied heat. This knowledge unveils the possibility of elastic spectral shaping of C-FBG, which will allow it to further find new applications.
关键词： fiber Bragg grating,Chirped fiber Bragg grating,confined heating
更新于2025-09-23 15:23:52
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The Analysis and Optimization of Broadband Fiber Optical Parametric Amplifiers Pumped by Chirped Pulses
摘要： The broadband gain properties of fiber optical parametric amplifiers pumped both by one and two chirped pump pulses are investigated for the amplification of ultrashort pulses, analytically with the gain spectrum calculated in both the anti-Stokes and Stokes side. The influence of chirp rate and time delay on the gain spectrum of fiber-based optical parametric chirped pulse amplification is mainly explored. It is shown that, the chirp rate and time delay distinctly affect the second order dispersion and phase mismatching, leading to the gain variation, the two pump scheme provides broader gain bandwidth, especially under the condition of the two chirp rate with low absolute value, a genetic algorithm is employed to optimize the gain characteristics for realizing a flatter and wider, high gain that is useful for the ultrashort pulse system.
关键词： chirped pulse,ultrashort pulse,Broadband fiber optical parametric amplifiers,gain optimization
更新于2025-09-23 15:23:52
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Spectral characteristics of periodic tunnelling of chirped soliton in nonautonomous system with external potentials
摘要： We present an exact chirped soliton solution for a nonautonomous system with external potentials and periodic nonlinear barriers/wells (NBs/NWs). Based on the soliton solution, we disclose the interesting spectral features of the chirped solitons through periodic NBs and NWs. In addition to the spectrum being broadened through NBs and being compressed through NWs, we find that distinct spectral characteristics of the chirped soliton appear at the centre, leading and trailing edges of NBs and NWs, which are related to the chirp of the solitons, the period of NBs/NWs and external potentials. When the period of NBs/NWs decreases and the soliton chirp increases, the spectrum appears additional broadening near the leading and trailing edges of both NBs and NWs, but the spectral widths at the centre of both NBs and NWs remain unchanged. Moreover, the linear potential affects the trajectory and the frequency shift of the chirped soliton.
关键词： chirped soliton,nonautonomous NLS equation,Periodic tunnelling,external potentials
更新于2025-09-23 15:22:29
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A Tunable Optimized Low-Temperature Sensor Based on the Hybrid Photonic Crystals (F4/Bg5/F4) and (Bg5/F4/Bg5)
摘要： In this paper, we present a novel type of low-temperature sensor based precisely on the symmetrical hybrid photonic crystals. Thanks to the two-fluid model and the transfer matrix method, we study the temperature sensitivity of the hybrid multilayers (F4/Bg5/F4) and (Bg5/F4/Bg5) where F4 represents the fourth iteration of the quasi-periodic Fibonacci sequence and Bg5 designates the multilayer Bragg mirror (HLS)5. We assume that the layers H, L, and S indicate precisely the dielectric materials of Bi4Ge3O12, SiO2, and YaBO2CuO7 superconductor one. The analysis of the transmittance spectra shows that the hybrid photonic crystal is more sensitive to the temperature than the periodic one. A higher sensibility value is reached due to the possible combination of the periodic and quasi-periodic sequences. Our investigation reveals that the photonic crystal (F4/Bg5/F4) is more sensitive to low temperature compared to (Bg5/F4/Bg5). The sensitivity is significantly affected by the position of quasi-periodic sequences. The sensitivity of such photonic crystals can be adequately controlled by applying a symmetrical chirping. The designed structures pave the way toward the achievement of a potential low-temperature sensor.
关键词： Low-temperature sensor,Tunable,Fibonacci,Photonic crystals,Chirped,TMM,Optimization
更新于2025-09-23 15:22:29
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Efficient cascaded wavelength conversion based on Stark-chirped rapid adiabatic passage
摘要： We demonstrate a highly efficient process of cascaded wavelength conversion among three states that is based on the Stark-chirped rapid adiabatic passage technique, and enables the achievement of nearly complete wavelength conversion in the mid-infrared laser generation process. By analyzing the relevant parameters in the model, we identify various factors that affect the efficiency of the conversion process. Compared with traditional cascaded wavelength conversion based on the technique of stimulated Raman adiabatic passage, the new conversion process not only maintains a high efficiency but also keeps the intermediate frequency strength low along the interacting length and achieves better stability when the relevant parameters change.
关键词： Stark-chirped rapid adiabatic passage,efficiency,cascaded wavelength conversion,stability,mid-infrared laser
更新于2025-09-23 15:22:29
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Suppression of four-wave mixing in a 22?×?10?Gbps dense wavelength division multiplexed system by linearly chirped fiber Bragg gratings
摘要： A scheme comprising two linearly chirped fiber Bragg gratings (LCFBGs) is proposed to suppress four-wave mixing (FWM) effects in a 22×10? Gbps dense wavelength division multiplexed (DWDM) system employing dispersion shifted fiber with 0.2? nm channel spacing. The FWM reduction in our proposed scheme has been studied by varying the input signal power per channel from ? 2 to + 10? dBm. The parameters of LCFBGs are optimized to obtain a maximum quality factor for all 22 channels. The proposed method is effective even at high input power (10?dBm) and provides a simple, cost effective way to improve the transmission performance in DWDM system.
关键词： Dense wavelength division multiplexing (DWDM),Dispersion,Four wave mixing (FWM),Chirped fiber Bragg gratings,Channel spacing
更新于2025-09-23 15:21:21
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Transiently changing shape of the photon number distribution in a quantum-dota??cavity system driven by chirped laser pulses
摘要： We have simulated the time evolution of the photon number distribution in a semiconductor quantum-dot–microcavity system driven by chirped laser pulses and compare with unchirped results. When phonon interactions with the dot are disregarded—thus corresponding to the limit of atomic cavity systems—chirped pulses generate photon number distributions that change their shape drastically in the course of time. Phonons have a strong and qualitative impact on the photon statistics. The asymmetry between phonon absorption and emission destroys the symmetry of the photon distributions obtained for positive and negative chirps. While for negative chirps transient distributions resembling thermal ones are observed, for positive chirps the photon number distribution still resembles its phonon-free counterpart but with overall smoother shapes. In sharp contrast, using unchirped pulses of the same pulse area and duration wave packets are found that move up and down the Jaynes-Cummings ladder with a bell shape that changes little in time. For shorter pulses and lower driving strength Rabi-like oscillations occur between low photon number states. For all considered excitation conditions transitions between sub- and super-Poissonian statistics are found at certain times. For resonant driving with low intensity the Mandel parameter oscillates and is mostly negative, which indicates a nonclassical state in the cavity ?eld. Finally, we show that it is possible that the Mandel parameter dynamically approaches zero and still the photon distribution exhibits two maxima and thus is far from being a Poissonian.
关键词： Mandel parameter,photon number distribution,chirped laser pulses,quantum-dot–cavity system,phonon interactions
更新于2025-09-23 15:21:01
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A pump-probe scheme with a single chirped pulse to image electron and nuclear dynamics in molecules
摘要： A single chirped few-femtosecond pulse can be used to control and image coupled electron-nuclear dynamics. Using full ab initio simulations of the simplest molecule, H+2, as a prototype target, we show that for intermediate values of the chirp, interference between sequential and direct contributions enables significant control over ionization yields, even when taking into account the effective decoherence introduced by nuclear motion and the presence of an electronic continuum. For larger values of the chirp, the single chirped pulse reproduces a classical pump-probe setup, with the chirp parameter mapping an effective time delay between the pumping and probing frequencies of the pulse. After demonstrating this numerically, we present a full analytical solution for the two-photon ionization amplitudes that provides an intuitive analogy between the molecular dynamics induced by a single chirped pulse and a traditional pump-probe setup.
关键词： pump-probe scheme,attosecond science,chirped pulse,molecular ionization,electron-nuclear dynamics
更新于2025-09-23 15:21:01
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Effect of a tightly focused chirped Gaussian laser pulse on electron acceleration in helical undulator
摘要： The chirped-pulse inverse free electron laser (CIFEL) interaction has been investigated by considering a tightly focused chirped Gaussian laser pulse and a helical undulator in vacuum. We consider the more realistic description of a laser, i.e., seventh-order calculation in the spatial term and first-order calculation in the temporal term. Numerical calculations show that better electron acceleration can be achieved using a tightly focused chirped Gaussian laser pulse in the CIFEL scheme. The investigation shows that a 10 MeV electron can be accelerated up to a few giga-electron volts energy with the present available laser parameters.
关键词： CIFEL,tightly focused chirped Gaussian laser pulse,helical undulator,electron acceleration,chirped-pulse inverse free electron laser
更新于2025-09-23 15:19:57