- 标题
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- 实验方案
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Femtosecond Red and Near-Infrared Lasers Due to Cascaded-Raman-Assisted Four-Wave Mixing in a Nonlinear Yb-Doped Fiber Amplifier
摘要： We demonstrated a straightforward approach to generate red and near-infrared laser emissions by a Raman-assisted four wave mixing (FWM) process in a nonlinear Yb-doped fiber amplifier, delivering 342 fs pulses of 241 nJ at 864 nm, 834 fs pulses of 21 nJ at 751 nm, and 1.9 ps pulses of 3.8 μJ at 1030 nm. A pair of gratings was employed as the pre-compressor to promote the intensity of the fundamental wave in the main amplifier. Multiple wavelengths from 751 to 1273 nm resulted due to cascaded-Raman-assisted FWM. The pre-compression also underlay the achievement of 25.1, 701, and 2000 kW peak power for the red (751 nm), near-infrared (864 nm), and fundamental (1030 nm) components respectively, which restrained the gain narrowing effect during the amplification. It finally led to shorter pulse duration under increased power.
关键词： femtosecond fiber laser,four-wave mixing,fiber amplifier
更新于2025-09-23 15:19:57
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Theoretical Investigation of an Alcohol-Filled Tellurite Photonic Crystal Fiber Temperature Sensor Based on Four-Wave Mixing
摘要： For this study, a temperature sensor utilizing a novel tellurite photonic crystal fiber (PCF) is designed. In order to improve the sensor sensitivity, alcohol is filled in the air holes of the tellurite PCF. Based on the degenerate four-wave mixing theory, temperature sensing in the mid-infrared region (MIR) can be achieved by detecting the wavelength shift of signal waves and idler waves during variations in temperature. Simulation results show that at a pump wavelength of 3550 nm, the temperature sensitivity of this proposed sensor can be as high as 0.70 nm/°C. To the best of our knowledge, this is the first study to propose temperature sensing in the MIR by drawing on four-wave mixing (FWM) in a non-silica PCF.
关键词： mid-infrared region,tellurite photonic crystal fiber,four-wave mixing,temperature sensor
更新于2025-09-23 15:19:57
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Four-wave mixing in spin-orbit coupled Bose-Einstein condensates
摘要： We describe possibilities of spontaneous, degenerate four-wave mixing (FWM) processes in spin-orbit coupled Bose-Einstein condensates. Phase matching conditions (i.e., energy and momentum conservation laws) in such systems allow one to identify four different configurations characterized by involvement of distinct spinor states in which such a process can take place. We derived these conditions from first principles and then illustrated dynamics with direct numerical simulations. We found, among others, the unique configuration, where both probe waves have smaller group velocity than pump wave and proved numerically that it can be observed experimentally under proper choice of the parameters. We also reported the case when two different FWM processes can occur simultaneously. The described resonant interactions of matter waves is expected to play important role in the experiments of BEC with artificial gauge fields. Beams created by FWM processes are important source of correlated particles and can be used the experiments testing quantum properties of atomic ensembles.
关键词： four-wave mixing,Bose-Einstein condensate,Spin-orbit coupling
更新于2025-09-23 15:19:57
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Nonlinear Optics in Dielectric Guided-Mode Resonant Structures and Resonant Metasurfaces
摘要： Nonlinear optics is an important area of photonics research for realizing active optical functionalities such as light emission, frequency conversion, and ultrafast optical switching for applications in optical communication, material processing, precision measurements, spectroscopic sensing and label-free biological imaging. An emerging topic in nonlinear optics research is to realize high efficiency optical functionalities in ultra-small, sub-wavelength length scale structures by leveraging interesting optical resonances in surface relief metasurfaces. Such artificial surfaces can be engineered to support high quality factor resonances for enhanced nonlinear optical interaction by leveraging interesting physical mechanisms. The aim of this review article is to give an overview of the emerging field of nonlinear optics in dielectric based sub-wavelength periodic structures to realize efficient harmonic generators, wavelength mixers, optical switches etc. Dielectric metasurfaces support the realization of high quality-factor resonances with electric field concentrated either inside or in the vicinity of the dielectric media, while at the same time operate at high optical intensities without damage. The periodic dielectric structures considered here are broadly classified into guided-mode resonant structures and resonant metasurfaces. The basic physical mechanisms behind guided-mode resonances, electromagnetically-induced transparency like resonances and bound-states in continuum resonances in periodic photonic structures are discussed. Various nonlinear optical processes studied in such structures with example implementations are also reviewed. Finally, some future directions of interest in terms of realizing large-area metasurfaces, techniques for enhancing the efficiency of the nonlinear processes, heterogenous integration, and extension to non-conventional wavelength ranges in the ultra-violet and infrared region are discussed.
关键词： harmonic generation,guided-mode resonance,four-wave mixing,Mie scattering,optical resonances,nonlinear optics,sub-wavelength gratings,Fano resonances,optical switching
更新于2025-09-23 15:19:57
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Tunable hybrid spectral filter and time-division multiplexing of second-order fluorescence controlled by phonon and dressing on Pr <sup>3+</sup> :YSO
摘要： Atom-like nonlinear responses of rare earth doped crystal Pr3+:Y2SiO5 (Pr3+: YSO) exhibit unique features compared with other nonlinear crystals. The responses become more interesting, while Pr3+: YSO is modulated simultaneously by temperature and multi-parameters related to dressed state. The generations of Stokes and fluorescence (FL) signals are demonstrated in both time and spectral domains. Here, we are presenting a new controlling strategy by interaction between dressing and phonon on Pr3+: YSO to manipulate the intensity of Stokes and FL signals. Interaction between dressing and phonon leads to more stable nonlinear response of the YSO crystal, which is very important for integrated quantum photonic device stability and multi-functionality. Also, we have realized tunable hybrid spectral filter (narrow-band pass notch filter (NBPNF), narrow-band stop notch filter (NBSNF)) and time-division multiplexing router on Pr3+: YSO by controlling the interaction between dressing and phonons. Tunable hybrid spectral filter and pure NBPNF are realized from dressing dip of Autler-Townes (AT) splitting and spectral intensity Stokes emission peak. Also, time-division multiplexing router is realized by time-domain adiabatic expansion. Furthermore, optical switch between tunable hybrid spectral filter to pure NBPNF is realized from dressing dip (AT splitting) to spectral intensity Stokes emission peak. Our experimental results suggests advanced technique for realizing tunable hybrid spectral filter with a contrast of about 98%, and optical time-division multiplexing router with channel equalization is about 85%.
关键词： four wave mixing,nonlinear optics,dressing,hybrid,optical device,fluorescence and phonon,filter
更新于2025-09-23 15:19:57
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Broadband ultrafast nonlinear optical studies revealing exciting multi-photon absorption coefficients in phase pure zero-dimensional Cs <sub/>4</sub> PbBr <sub/>6</sub> perovskite films
摘要： Lead halide perovskite nanocrystals (NCs) apart from their overwhelming optoelectronic applications have recently demonstrated promising nonlinear optical (NLO) properties such as strong two-photon absorption cross-sections (～105 GM), two-photon fluorescence, and saturable absorption even at very high peak intensity. Zero-dimensional perovskite-related materials (0-D PRMs) are a new class of materials offering a high exciton binding energy (Eg ≥ 180 meV) with a strong photoluminescence (PL) quantum yield in few cases. Herein, we report the broadband third-order NLO properties of phase pure Cs4PbBr6 0-D PRM achieved using the Z-scan and degenerate four-wave mixing techniques in the femtosecond regime. Considering the growing content of the fluorescent and non-fluorescent forms of this material, we have performed our studies on both of them. These perovskite NCs exhibited strong multi-photon absorption properties in the near-infrared region with two-photon absorption (2PA) (cross-section, σ2 = 10?43–10?44 cm4 s equivalent to ～106 GM) in the 500–800 nm region, three-photon absorption (3PA) (cross-section, σ3 ～10?73 cm6 s2) in the 900–1200 nm region and four-photon absorption (4PA) (cross-section, σ4 ～10?100 cm8 s3) in the 1300–1500 nm spectral region. These multi-photon absorption processes are explained using a simple band diagram. The measured NLO coefficients and cross-sections are fairly large when compared to some of the earlier reports on perovskite-based NCs. Cs4PbBr6 0-D PRM also demonstrated a large third-order NLO susceptibility χ(3) (～10?7 esu), which can be attributed to the strong quantum confinement arising from spatially isolated, exciton containing individual [PbBr6]4? octahedron. These results clearly suggest the potential of 0D-PRMs in applications such as photonics and ultrafast all-optical switching devices.
关键词： Z-scan,perovskite nanocrystals,ultrafast optics,degenerate four-wave mixing,multi-photon absorption,nonlinear optical properties
更新于2025-09-19 17:15:36
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Effects of higher-order dispersion on photon-pair generation by four-wave mixing
摘要： We present analytical results revealing the impact of higher-order dispersion on four-wave mixing in quantum applications. We derive fundamental relations between input and output modes in dispersive four-wave mixing processes and apply the theory to photon-pair generation. We analyze specific examples of four-wave-mixing configurations and find that, in some cases, spectral correlations are severely affected by dispersion while other cases are strongly unaffected. For the considered examples, we derive analytic conditions for dispersion cancellation, resulting in highly factorable two-photon states.
关键词： spectral correlations,higher-order dispersion,photon-pair generation,quantum applications,four-wave mixing,dispersion cancellation
更新于2025-09-19 17:15:36
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Closed-form FWM expressions accounting for the impact of modulation format
摘要： Four Wave Mixing (FWM) is one of the main transmission impairments in coherent optical systems and a broad gamut of analytical expressions calculating its power already exists in the literature. Most of these expressions, such as the GN-model, assume that due to the large values of accumulated dispersion, each transmitted signal behaves as stationary circular Gaussian noise, ignoring the dependence of FWM on the employed modulation format. This assumption leads to significant error especially in the case of quadrature-phase-shift keying (QPSK), in systems with small number of spans and in the dispersion managed case. In addition, the GN-model is inaccurate when applied to metro networks, due to the low accumulated dispersion. In this paper, we derive closed-form expressions which incorporate the impact of modulation format on FWM generation, extending and improving the accuracy compared to existing closed-form FWM expressions. Moreover, the proposed method includes terms that make it applicable to systems with small span lengths (<30 km), which is the case in metro networks. The accuracy of the proposed formulas is benchmarked against a numerical method, where the signal transmission is modeled using the split step fourier method (SSFM), for a wide range of system configurations and parameters.
关键词： coherent communications,nonlinear transmission performance,flexgrid networks,four wave mixing
更新于2025-09-19 17:15:36
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Ultrafast acoustic phonon scattering in CH <sub/>3</sub> NH <sub/>3</sub> PbI <sub/>3</sub> revealed by femtosecond four-wave mixing
摘要： Carrier scattering processes are studied in CH3NH3PbI3 using temperature-dependent four-wave mixing experiments. Our results indicate that scattering by ionized impurities limits the interband dephasing time (T2) below 30 K, with strong electron-phonon scattering dominating at higher temperatures (with a time scale of 125 fs at 100 K). Our theoretical simulations provide quantitative agreement with the measured carrier scattering rate and show that the rate of acoustic phonon scattering is enhanced by strong spin-orbit coupling, which modifies the band-edge density of states. The Rashba coefficient extracted from fitting the experimental results (γc = 2 eV ?) is in agreement with calculations of the surface Rashba effect and recent experiments using the photogalvanic effect on thin films.
关键词： electron-phonon scattering,carrier scattering,CH3NH3PbI3,four-wave mixing,Rashba effect
更新于2025-09-19 17:13:59
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PFI-ZEKE-photoelectron spectroscopy of N <sub/>2</sub> O using narrow-band VUV laser radiation generated by four-wave mixing in Ar using a KBBF crystal
摘要： A new nonlinear optical scheme relying on sum-frequency mixing in a KBe2BO3F2 crystal has been used to generate intense, broadly tunable, narrow-bandwidth, coherent vacuum-ultraviolet (VUV) radiation beyond 16 eV by resonance-enhanced four-wave mixing in Ar. The VUV radiation was used to record high-resolution pulsed-field-ionization zero-kinetic-energy photoelectron spectra of the N2O+ A+ ← N2O X photoionizing transition in the wave-number range from 132 000 cm?1 to 135 000 cm?1. The rotational structure of almost all vibrational levels of the A+ state with vibrational term values up to 2700 cm?1 could be resolved, and improved values of the first two adiabatic ionization energies of N2O, corresponding to the formation of the X+ 2Π3/2(000) J+ = 3/2 and A+ 2Σ+(000) N+ = 0 levels of N2O+ from the X 1Σ+(000) J′′ = 0 ground state [103 969.30(12) cm?1 and 132 197.70(12) cm?1, respectively], were derived. The rotational intensity distributions of the bands were found to depend strongly on the value of the vibrational angular momentum of the ionic levels. The vibrational structure is discussed in terms of previously reported effective-Hamiltonian analyses.
关键词： KBBF crystal,PFI-ZEKE-photoelectron spectroscopy,N2O,narrow-band VUV laser radiation,four-wave mixing
更新于2025-09-19 17:13:59