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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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Self-generating Brillouin fiber laser using highly nonlinear hafnium bismuth erbium-doped fiber
摘要： A compact Brillouin fiber laser (BFL) utilizing a newly developed hafnium bismuth erbium-doped fiber (HB-EDF), which functions as both the Brillouin and linear gain media, is realized in the absence of Brillouin pump. It is achieved by the self-Brillouin generation from a 0.2 m length of HB-EDF with high nonlinearity in a laser cavity. The self-generating BFL was obtained in both ring and linear laser cavities. Compared to the ring cavity, the BFL in the linear cavity produced more Brillouin stokes at a lower pump threshold. In the experiment, an eight-line comb with average spacing of 0.087 nm was generated at the HB-EDF pump power of 75.27 mW. This compact BFL has total cavity length of less than 0.5 m, and thus, this is the shortest gain medium reported.
关键词： hafnium bismuth erbium-doped fiber,self-generating Brillouin fiber laser,stimulated Brillouin scattering
更新于2025-11-28 14:23:57
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Widely tunable single bandpass microwave photonic filter based on dual-fiber stimulated Brillouin scattering
摘要： A new technique to achieve a single bandpass microwave photonic filter (MPF) with wide tunability based on stimulated Brillouin scattering is proposed. The MPF cascades the Brillouin frequency shifter and amplification based on a dual-fiber structure. The experimental results present a single bandpass MPF located at 21.4 GHz with a 3-dB bandwidth of 38 MHz and an out-of-band rejection ratio over 30 dB. The proposed single bandpass MPF also successfully demonstrates a wide-band tuning over 40 GHz, which is achieved by employing a frequency shifter based on carrier suppressed single-sideband modulation scheme in the structure.
关键词： Brillouin frequency shift,stimulated Brillouin scattering,fiber,microwave photonic filter,carrier suppressed single-sideband modulation
更新于2025-09-23 15:23:52
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Instantaneous microwave frequency measurement with high-resolution based on stimulated Brillouin scattering
摘要： A novel photonic method of instantaneous microwave frequency measurement (IMFM) based on Stimulated Brillouin scattering (SBS) is proposed. The principle of the technique is the employment of SBS effect to amplify/attenuate two adjacent frequency components, which result in a definite amplitude comparison function (ACF). Using this technique, the frequency of an unknown RF signal can be precisely obtained. Experimental results show the measurement capability of the proposed method over a frequency range of 0.47–23 GHz with a higher resolution of 8 MHz.
关键词： Amplitude comparison functions,Microwave photonics,Instantaneous microwave frequency measurement,Stimulated Brillouin scattering
更新于2025-09-23 15:23:52
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Nonlinear Optics || Stimulated Brillouin and Stimulated Rayleigh Scattering
摘要： We saw in Section 8.1 that light scattering can occur only as the result of fluctuations in the optical properties of a material system. A light-scattering process is said to be spontaneous if the fluctuations (typically in the dielectric constant) that cause the light-scattering are excited by thermal or by quantum-mechanical zero-point effects. In contrast, a light-scattering process is said to be stimulated if the fluctuations are induced by the presence of the light field. Stimulated light scattering is typically very much more efficient than spontaneous light scattering. For example, approximately one part in 105 of the power contained in a beam of visible light would be scattered out of the beam by spontaneous scattering in passing through 1 cm of liquid water. In this chapter, we shall see that when the intensity of the incident light is sufficiently large, essentially 100% of a beam of light can be scattered in a 1-cm path as the result of stimulated scattering processes.
关键词： Stimulated Rayleigh scattering,electrostriction,Stimulated Brillouin scattering,optical properties,light scattering
更新于2025-09-23 15:21:01
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SBS pulse compression using bulk fused silica by diode-pumped solid-state lasers at 1??kHz repetition rate
摘要： This study is focused on constructing a highly stable diode-pumped solid-state laser system by conducting experiments on high-repetition-rate SBS pulse compression using bulk fused silica. A multi-rod serial-connection structure is adopted for SBS expriments by comparing K8 glass and fused silica medium at a 10 Hz repetition rate. The optimized structure is obtained according to variation of the pump power density. Based on the optimized structure, fused silica-based SBS pulse compression is carried out in the range of 100–1000 Hz and the parameter performance of laser system after compression is also evaluated by comparing a HT270 liquid medium. Experimental results indicate that the energy e?ciency of fused silica-based SBS is improved by approximately 40% compared with that of K8 glass. Further, the energy relative standard deviation of fused silica-based SBS is reduced by approximately 88% compared with HT270 medium, indicating that bulk fused silica is advantageous for high-repetition-rate SBS pulse compression because of its un-?uidity, high thermal conductivity and power-load ability. In addition, a 1 kHz highly-stable sub-nanosecond compressed pulse is achieved using bulk fused silica medium at a pump energy of 50 mJ. Furthermore, the SBS energy e?ciency can be further improved by increasing the input energy.
关键词： Pulse compression,High repetition rate,Solid-state lasers,Sub-nanosecond pulse,Stimulated Brillouin scattering (SBS)
更新于2025-09-23 15:21:01
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The interaction of parametric instabilities from 3?? laser and 2?? laser in large-scale inhomogeneous plasmas
摘要： The interaction of parametric instabilities from 3ω laser and 2ω laser in large-scale inhomogeneous plasmas. The mechanism of energy transfer from 3ω pump light to stimulated Brillouin scattering (SBS) generated by 2ω pump light is proposed. The backscattering light of stimulated Raman scattering (SRS) generated by 3ω pump light can work as a seed of the SBS of 2ω pump light, which results in the increase of the later. Adding 2ω pump light into 3ω pump light will decrease the reflectivity of SBS generated from 3ω pump light. The total reflectivity will firstly decrease and then increase with increase of the ratio of 2ω light intensity to the intensity of 2ω and 3ω lights f = I2ω0/(I2ω0 + I3ω0), and will be controlled in a lower level when this ratio f is about 10% ? 20%. These results give a method to control the total reflectivity of SBS and SRS in inertial confinement fusion (ICF) by adding 2ω light into 3ω light.
关键词： inertial confinement fusion,2ω laser,3ω laser,parametric instabilities,stimulated Raman scattering,stimulated Brillouin scattering,large-scale inhomogeneous plasmas
更新于2025-09-23 15:19:57
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Calculation of Direct Drive Targets for Megajoule Laser Facilities with Radiation in the Second and Third Harmonics of Nd Laser
摘要： The numerical results for cryogenic direct drive targets of megajoule facilities with radiation in the second and third harmonics of a Nd laser are presented. The calculations were performed with the 1D radiation hydrodynamics code ERA with the laser light absorption model that takes into account stimulated Brillouin scattering (SBS), generation of fast electrons in the processes of two-plasmon decay (TPD), and stimulated Raman scattering (SRS). The verification of the developed models was carried out on the basis of the comparison with experiments performed at the OMEGA and NIF facilities. The ignition margin (WQ) of nonuniform fusion targets with an allowance for energy losses due to radiation transfer and heat conduction from the hot spot was the objective of the target optimization. The calculations showed that SBS and target heating by fast electrons generated in TPD and SRS fatally reduce WQ of targets with a CH ablator for the megajoule laser with wavelength λ = 0.53 μm. The possibilities of decreasing these effects by replacing a CH ablator with a glass ablator and reducing the laser intensity upon increasing the target aspect ratio are considered. However, in both cases, WQ remains substantially below unity for the laser with wavelength λ = 0.53 μm. The ignition margin increases by a factor of ~2 upon transition from the second to the third harmonic of a Nd laser. A glass ablator almost eliminates fast electrons in calculation with the laser wavelength λ = 0.35 μm. In this case, if SBS is reduced by a factor of 3–4 via shifting the laser emission lines in the neighboring channels by Δλ ≈ 10–20 ?, the ignition margin WQ ~ 2 and a fusion energy yield of ~50 MJ are obtained in the 1D calculation for a laser energy of ~2 MJ and the third harmonic of a Nd laser.
关键词： megajoule laser facilities,two-plasmon decay,fast electron generation,direct drive targets,stimulated Raman scattering,thermonuclear ignition margin of target,stimulated Brillouin scattering
更新于2025-09-23 15:19:57
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Pump depletion and hot-electron generation in long-density-scale-length plasma with shock-ignition high-intensity laser
摘要： Two-dimensional particle-in-cell simulations for laser plasma interaction with laser intensity of 1016 W/cm2, plasma density range of 0.01–0.28nc, and scale length of 230–330 μm showed signi?cant pump depletion of the laser energy due to stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS) in the low-density region (ne = 0.01–0.2nc). The simulations identi?ed hot electrons generated by SRS in the low-density region with moderate energy and by two-plasmon-decay near ne = 0.25nc with higher energy. The overall hot electron temperature (46 keV) and conversion ef?ciency (3%) were consistent with the experiment’s measurements. The simulations also showed arti?cially reducing SBS would lead to stronger SRS and a softer hot-electron spectrum.
关键词： pump depletion,two-plasmon-decay,stimulated Raman scattering,stimulated Brillouin scattering,laser plasma interaction,hot-electron generation
更新于2025-09-23 15:19:57
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Nonlinear Optics in Microspherical Resonators
摘要： Nonlinear frequency generation requires high intensity density which is usually achieved with pulsed laser sources, anomalous dispersion, high nonlinear coefficients or long interaction lengths. Whispering gallery mode microresonators (WGMRs) are photonic devices that enhance nonlinear interactions and can be exploited for continuous wave (CW) nonlinear frequency conversion, due to their capability of confine light for long time periods in a very small volume, even though in the normal dispersion regime. All signals must be resonant with the cavity. Here, we present a review of nonlinear optical processes in glass microspherical cavities, hollow and solid.
关键词： kerr nonlinearity,optomechanical oscillations,stimulated brillouin scattering,optical resonators,whispering gallery mode
更新于2025-09-23 15:19:57