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The biomechanical properties of cells and tissues play an important role in our fundamental understanding of the structures and functions of biological systems at both the cellular and subcellular levels. Recently, Brillouin microscopy, which offers a label-free spectroscopic means of assessing viscoelastic properties in vivo, has emerged as a powerful way to interrogate those properties on a microscopic level in living tissues. However, susceptibility to photodamage and photobleaching, particularly when high-intensity laser beams are used to induce Brillouin scattering, poses a significant challenge. This article introduces a transformative approach designed to mitigate photodamage in biological and biomedical studies, enabling nondestructive, labelfree assessments of mechanical properties in live biological samples. By leveraging quantum-light-enhanced stimulated Brillouin scattering (SBS) imaging contrast, the signal-to-noise ratio is significantly elevated, thereby increasing sample viability and extending interrogation times without compromising the integrity of living samples. The tangible impact of this methodology is evidenced by a notable three-fold increase in sample viability observed after subjecting the samples to three hours of continuous squeezed-light illumination, surpassing the traditional coherent lightbased approaches. The quantum-enhanced SBS imaging holds promise across diverse fields, such as cancer biology and neuroscience where preserving sample vitality is of paramount significance. By mitigating concerns regarding photodamage and photobleaching associated with high-intensity lasers, this technological breakthrough expands our horizons for exploring the mechanical properties of live biological systems, paving the way for an era of research and clinical applications. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Jilin University (Science Edition) / Jilin Daxue Xuebao (Lixue Ban) is the property of Zhongguo Xue shu qi Kan (Guang Pan Ban) Dian zi Za zhi She and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study investigates the possibility of achieving a slow signal field at the level of single photons inside nanofibers by exploiting stimulated Brillouin scattering, which involves a strong pump field and the vibrational modes of the waveguide. The slow signal is significantly amplified for a pump field, with a frequency higher than that of the signal and attenuated for a lower pump frequency.We introduce a configuration for obtaining a propagating slow signal without gain or loss and with a relatively wide bandwidth. This process involves two strong pump fields with frequencies both higher and lower than that of the signal where the effects of signal amplification and attenuation compensate each other. We account for thermal fluctuations due to the scattering of thermal phonons and identify conditions under which thermal contributions to the signal field are negligible. The slowing of light through Brillouin optomechanics may serve as a vital tool for optical quantum information processing and quantum communications within nanophotonic structures. [ABSTRACT FROM AUTHOR]

An expression for the threshold power of stimulated Brillouin scattering (SBS) in optical fibres is derived for pumps with arbitrary power spectra. It is compared to spectrally independent approximations for the SBS threshold and is found to be in close agreement when the assumptions used for the approximations are applied. This expression is then used to examine the variation of the SBS threshold with pump power spectrum. The analysis of the results shows a significantly lower SBS threshold than that predicted by the more commonly used expressions. Additionally, a connection is made between decreasing the pump power spectral density, which is dependent on spectral shape of the pump, and increasing the SBS threshold power. [ABSTRACT FROM AUTHOR]

Stimulated Brillouin scattering (SBS) is a significant nonlinear optical phenomenon utilized across various fields. Its applications span optical sensing, microwave photonics, and all-optical signal processing. In the current information-driven era, the laser industry is imposing increasingly stringent demands on laser technologies, thus propelling integrable on-chip SBS devices into a pivotal research trajectory. Simultaneously, the quest for materials manifesting heightened SBS effects has emerged as a primary focal point in optical fiber transmission endeavors. Lithium niobate (LN) stands out as a promising nonlinear optical material endowed with numerous exemplary attributes. These encompass a high refractive index, fostering potent photon- phonon interactions, low loss characteristics, and high integration potential. Consequently, employing LN as a material for Brillouin lasers promises to enhance certain aspects of laser performance and enable more comprehensive research into Brillouin lasers. In this paper, a micro-ring waveguide structure with LN as the main material is constructed, and the forward gain of stimulated Brillouin scattering, the distribution of electric field in multiple modes and the maximum tunable range are further analyzed. The simulation results exhibit that the tunable forward SBS effect can be achieved in the LN optical waveguides, the maximum forward Brillouin gain can reach 1.34W-1 m-1. Additionally, the tunable phonon frequency can range from 1 GHz to 31 GHz, effectively doubling that of silicon ring waveguides and thus extending the range of phonon tunability. Therefore, the LN micro-ring waveguide structure provides a new reference direction for the construction of a new tunable laser and a new idea for the generation of lasers to find a Brillouin medium with high SBS effect. [ABSTRACT FROM AUTHOR]

Structured light with multiple degrees of freedom has inspired many advanced applications, and its nonlinear control plays an important role in the interactions between light and matter. Stimulated Brillouin scattering (SBS) based on light–sound coupling can be used to realize wavefront‐reversal nonlinear reflection of ordinary light; consequently, it is used to correct wavefront aberrations in high‐power laser systems. However, high‐fidelity wavefront reversal of structured light with orbital angular momentum and high‐reflectivity single‐end SBS of weak incident waves remain challenging. Here, the authors propose a cross‐pump focused SBS scheme that enables wavefront reversal with high fidelity, low threshold, and high reflectivity for arbitrary structured light. The authors demonstrate the capability of this approach to perform conformal and enhanced SBS reflections with a fidelity of >95% and reflectivity of >100%. Compared with the conventional focused SBS configuration, the SBS threshold is reduced by more than ten times, and wavefront reversal of weakly structured light is realized. This proof‐of‐principle study provides a high‐performance SBS platform with potential implications for high‐power structured lasers, high signal‐to‐noise‐ratio microscopy imaging, and the development of nonlinear optics with structured light. [ABSTRACT FROM AUTHOR]

Brillouin microscopy (BM) is an emerging technique for all‐optical mechanical imaging without the need for physical contact with the sample or for an external mechanical stimulus. However, BM often retrieves a single Brillouin frequency shift for multiple mechanically different materials of structures and/or in regions—sufficiently larger than the phonon wavelength—inside the volume and its surroundings, resulting in significantly limited mechanical specificity in the Brillouin shift images produced. Here, a new physics‐driven model selection framework is developed based on information theory and a physical‐statistical overfit Brillouin water peak threshold that enables the robust identification of single‐ and multi‐peak Brillouin signatures in the sample pixels. The model selection framework is applied to Brillouin data of material interfaces and living NIH/3T3 cells measured by stimulated Brillouin scattering (SBS) microscopy, facilitating the quantification of the Brillouin frequency shift of materials in different regions of the sample and significantly improving mechanical specificity compared with the standard single peak fitting analysis. [ABSTRACT FROM AUTHOR]

Copyright of Journal of National University of Defense Technology / Guofang Keji Daxue Xuebao is the property of NUDT Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, we report the generation of multi-wavelength light sources through enhanced four-wave-mixing processes using a straightforward and adaptable dual-frequency Brillouin fiber laser. This passive optical and nonreciprocal cavity is first tested and analyzed with long fiber lengths up to 1 km in the 1.55 μm telecommunication C band and then in the 2-μm waveband. In the latter case, we demonstrate that our fiber cavity enables efficient multiple four-wave mixings, in the continuous-wave regime, which are commonly inaccessible in long silica-fibers due to increased losses. We also report on the tunable repetition rate from tens of GHz to hundreds of GHz, by simply changing the frequency spacing between the two continuous-wave pumps. The coherence limitations of our all-fiber system are discussed, along with the impact of the dispersion regime of the nonlinear fiber that forms the cavity. [ABSTRACT FROM AUTHOR]

The research on laser induced breakdown mechanism of charge coupled devices (CCDs) brings new insights into photoelectric countermeasures. So far combined laser irradiation has been proved to be a more effective measure to destroy CCD. Due to the limitation of short-pulse laser combination method, the mechanism of CCD damage caused by combined short-pulse laser remains unexplored. Here, the distribution of temperature and stress field during the interaction between a combined short-pulse laser and a CCD is analyzed. A nanosecond/picosecond combined short-pulse laser system based on Stimulated Brillouin Scattering (SBS) pulse compression technique is designed. The damage threshold (DT) and properties of CCD by combined laser irradiation are characterized. The results show that the complete DT of combined laser induced CCD breakdown is only 103 mJ/cm2, which is only 44% of that of picosecond laser. The main cause of combined short-pulse laser induced CCD breakdown is short circuit (SC) between silicon substrate and silicon electrode. [ABSTRACT FROM AUTHOR]

The optical power of a single line in optical frequency combs (OFCs) is inherently weak, so the extraction and amplification of a single OFC line is required for many high‐precision applications. In this work, a high gain, narrowband, and all‐polarization‐maintaining (PM) fiber Brillouin amplifier is introduced to address this issue. The use of PM fiber as the gain medium provides higher Brillouin gain and avoids polarization sensitivity to thermal and acoustic disturbance. The gain fiber is reduced to tens of meters with higher pump power, which is beneficial for the phase quality of the amplified comb line. Numerical simulations and experiments are performed to investigate the features of the Brillouin amplification process for an individual OFC line. Notably, direct generation of a Watt‐level single‐mode laser from an OFC is demonstrated, with a signal‐to‐noise‐ratio (SNR) of 47 dB and a side‐mode‐suppression‐ratio (SMSR) exceeding 60 dB, which represents the highest power, and best SNR and SMSR performance ever reported, to the best of the knowledge. [ABSTRACT FROM AUTHOR]

Optical up-conversion photonic Doppler velocimetry (PDV) based on stimulated Brillouin Scattering (SBS) with an all-fiber link structure is proposed in this article. Because SBS limits the laser power transmitted by a fiber over long distances, the probe does not have enough outgoing light to reach the measured surface and cannot receive the signal light. Traditionally, SBS is avoided, but it is a phase-conjugated light and shifts down relative to the source light, so it can be used as a reference light in the laser interference structure to achieve up-conversion heterodyne velocimetry. Compared with general homodyne velocimetry (DPS), SBS-PDV naturally upconverts and has more interference fringes and higher resolution at low-speed measurement. In the gas multiple reflection impact compression experiment, the velocity measurement results of SBS-PDV and dual-laser heterodyne Velocimetry (DLHV) are basically consistent, and the accuracy is better than 0.8%. Due to its coaxial heterodyne optical path, this kind of photonic Doppler velocimetry is suitable for low-velocity and long-distance practical applications in the field of shock wave physics. [ABSTRACT FROM AUTHOR]

A pulse duration compression technique that combines stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS) was presented in this study, achieving an output pulse duration of 48.3 ps. The feasibility of this approach has been experimentally demonstrated. To be specific, a pulse duration of 7.4 ns is compressed to 48.3 ps with an energy of 5.27 mJ, and the energy efficiency of the SRS pulse duration compression system is up to 21.84%. Moreover, this study provides a practical method for reliably generating high-energy short pulses. [ABSTRACT FROM AUTHOR]

This study investigates the possibility of achieving a slow signal field at the level of single photons inside nanofibers by exploiting stimulated Brillouin scattering, which involves a strong pump field and the vibrational modes of the waveguide. The slow signal is significantly amplified for a pump field, with a frequency higher than that of the signal and attenuated for a lower pump frequency. We introduce a configuration for obtaining a propagating slow signal without gain or loss and with a relatively wide bandwidth. This process involves two strong pump fields with frequencies both higher and lower than that of the signal where the effects of signal amplification and attenuation compensate each other. We account for thermal fluctuations due to the scattering of thermal phonons and identify conditions under which thermal contributions to the signal field are negligible. The slowing of light through Brillouin optomechanics may serve as a vital tool for optical quantum information processing and quantum communications within nanophotonic structures.

Stimulated Brillouin scattering (SBS) is a significant nonlinear optical phenomenon utilized across various fields. Its applications span optical sensing, microwave photonics, and all-optical signal processing. In the current information-driven era, the laser industry is imposing increasingly stringent demands on laser technologies, thus propelling integrable on-chip SBS devices into a pivotal research trajectory. Simultaneously, the quest for materials manifesting heightened SBS effects has emerged as a primary focal point in optical fiber transmission endeavors. Lithium niobate (LN) stands out as a promising nonlinear optical material endowed with numerous exemplary attributes. These encompass a high refractive index, fostering potent photon-phonon interactions, low loss characteristics, and high integration potential. Consequently, employing LN as a material for Brillouin lasers promises to enhance certain aspects of laser performance and enable more comprehensive research into Brillouin lasers. In this paper, a micro-ring waveguide structure with LN as the main material is constructed, and the forward gain of stimulated Brillouin scattering, the distribution of electric field in multiple modes and the maximum tunable range are further analyzed. The simulation results exhibit that the tunable forward SBS effect can be achieved in the LN optical waveguides, the maximum forward Brillouin gain can reach 1.34W−1 m−1. Additionally, the tunable phonon frequency can range from 1 GHz to 31 GHz, effectively doubling that of silicon ring waveguides and thus extending the range of phonon tunability. Therefore, the LN micro-ring waveguide structure provides a new reference direction for the construction of a new tunable laser and a new idea for the generation of lasers to find a Brillouin medium with high SBS effect.

The research on laser induced breakdown mechanism of charge coupled devices (CCDs) brings new insights into photoelectric countermeasures. So far combined laser irradiation has been proved to be a more effective measure to destroy CCD. Due to the limitation of short-pulse laser combination method, the mechanism of CCD damage caused by combined short-pulse laser remains unexplored. Here, the distribution of temperature and stress field during the interaction between a combined short-pulse laser and a CCD is analyzed. A nanosecond/picosecond combined short-pulse laser system based on Stimulated Brillouin Scattering (SBS) pulse compression technique is designed. The damage threshold (DT) and properties of CCD by combined laser irradiation are characterized. The results show that the complete DT of combined laser induced CCD breakdown is only 103 mJ/cm2, which is only 44% of that of picosecond laser. The main cause of combined short-pulse laser induced CCD breakdown is short circuit (SC) between silicon substrate and silicon electrode.

Copyright of Laser Technology is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We have demonstrated a simple all-fiber thulium (Tm) laser Q-switched by stimulated Brillouin scattering (SBS). The maximum output pulse energy was 80 μJ. This allowed us to generate a broadband spectrum directly at the laser outputs. For the first time, we measured the fine structure of the output pulses with a resolution of less than 100 ps. It was found that the SBS Q-switched laser is capable of generating bunches of picosecond pulses. The effect of modulation instability on the pulse decay is discussed. The potential application of the investigated laser radiation for producing destructive effects on soft biological tissues has been demonstrated. [ABSTRACT FROM AUTHOR]

Fiber optic parametric and phase sensitive amplifiers (PSA) are interesting for modern day communication technologies due to their low noise and high gain amplification properties with a potential for all optical signal processing and wide band operation. PSAs are typically employed in either a single pump or dual pump configuration. In this article we explore the utilities of both configurations, however considering a fiber with a longitudinally varying dispersion profile. For the single pump case, PSA operation at large pump-signal detunings, that arise due to the longitudinal dispersion variation, were studied numerically, and recipes of using the system as a wide band wavelength selective filter were laid out. For the dual-pump case, emphasis was laid on achieving a larger signal gain, by reducing stimulated Brillouin scattering (SBS) that prevents large pump power transport through the nonlinear fiber. First, the effects of dispersion variation on the gain of a dual pump PSA were studied analytically and numerically in order to optimize the dispersion variation profile, neglecting SBS processes. Then we independently studied the SBS dynamics of the system numerically. A sinusoidally dispersion oscillating fiber (DOF) was found to be an optimal candidate with respect to its PSA and SBS performances. To establish this claim, we also experimentally compared the performance of an available DOF over a standard highly nonlinear fiber (HNLF) that has a constant dispersion profile and established its utility for designing a high gain PSA system, thanks to the SBS mitigation due to the longitudinal dispersion variation of the fiber. [ABSTRACT FROM AUTHOR]

We demonstrate the generation of multiple lasing wavelength in the L- and U-band from a Brillouin-Raman fiber laser. It was designed in a full-open cavity with a dispersion compensating fiber section as the nonlinear and Raman gain medium. A broadband source originated from the amplified spontaneous emission of an erbium-ytterbium-doped fiber amplifier was employed as the primary Raman pump. The proposed fiber laser system required a threshold power of 400 mW to initiate its first Brillouin Stokes line with 0.165 nm wavelength spacing. A total of 397 Stokes lines within 3-dB flatness of peak power extended from 1609.7 to 1675.0 nm corresponding to 65.3 nm wavelength range were obtained at the pump power of 850 mW. The utilization of broadband Raman pump source has enhanced the spectral bandwidth of multiwavelength generation. This approach is simple and can be employed to other wavelength ranges subject to the availability of the broadband pump source. [ABSTRACT FROM AUTHOR]

The stimulated Brillouin scattering (SBS) effect, a new approach to the combination of solid-state lasers, can be actualized via coherent synthesis. In this paper, a solid-state laser based on SBS passive phase locking, utilizing the master oscillator power amplifier (MOPA) structure at the front end of the lasers, provides the amplification of the Stokes light subsequently generated. In order to reduce the influence of thermal effects on beam quality, beam-split amplification has been adopted with the same phase locking used by the back injection of the Stokes pulse. With the advantage of the combined scheme, the energy extraction efficiency of SBS coherent combination can be reached at 91.8% with coherent fringe visibility of 83%. Therefore, it provides a new way to improve the brightness through realizing the coherent combination of multi-channel solid-state lasers. [ABSTRACT FROM AUTHOR]

Three different stimulated Brillouin scattering (SBS) configurations in perfluorooctane were experimentally compared to achieve the ultimate compression of ~1.1 ns pulses from a commercially available Nd:YAG mini-laser. These schemes contained either a focusing lens and a plane feedback mirror, a spherical mirror, or variable pulse splitting to provide self-seeding of the SBS. In the optimal configuration with a focusing lens and return mirror, 93 ps pulses with an energy of 9.5 mJ were achieved at the output of the double-pass phase-conjugated Nd:YAG amplifier. The resulting diffraction-free, high-quality beams with M2~1.2 and excellent pointing stability are of practical interest for scientific, medical, and industrial applications. [ABSTRACT FROM AUTHOR]

In this article, a broadband frequency measurement system based on optical spectrum manipulation and stimulated Brillouin scattering (SBS) is proposed and experimentally demonstrated, which can implement wide-range and high-resolution frequency measurement, and generate corresponding broadband interference signals in some frequency bands, that is, it has versatility. Since the frequency range of the pump light to excite SBS is expanded based on the optical spectrum manipulation and high resolution is ensured by the narrow scattering spectrum of SBS, high-resolution spectrum measurement covering a wide frequency band is finally implemented. In addition, the double sideband pump light can be used as the source of electronic interference signal. In the experiments, the frequency measurement range of the proposed system is tested to be 0.03–44 GHz, and the resolution is up to 3 MHz. Furthermore, the frequency measurement and electronic interference sharing the same work band can be carried out in the ranges of 6.3367–7.8367 GHz and 20.36–22.16 GHz.

We propose and experimentally demonstrate an approach to generate triangular-shaped microwave signals based on optical polarization processing and stimulated Brillouin amplification, using a polarization modulator (PolM) and a fiber Brillouin amplifier. The odd- and even-order optical sidebands become polarized in mutually orthogonal directions by external modulating a continuous-wave laser light using the PolM. Then the odd-order optical sidebands are selected by a polarizer while the even-order optical sidebands are suppressed. Moreover, the power ratio of the odd-order optical sidebands is controlled by adjusting the modulation index. To generate triangular waveforms, an optical carrier recovery process is implemented by jointly controlling the direction $\boldsymbol{\alpha }$ of the polarizer transmission axis and the amplification effect from the stimulated Brillouin scattering. After photodetection, Fourier harmonics are produced by beating the amplified optical carrier with the odd-order optical sidebands, which synthesizes triangular-shaped microwave waveforms. The effect of $\boldsymbol{\alpha }$ on the generated waveform is analyzed theoretically and demonstrated experimentally. In the proof-of-concept experiment, triangular-shaped microwave signals with small root-mean-square error at repetition frequencies of 10, 11, and 12 GHz are successfully generated, demonstrating flexible tunability and excellent waveforms.

The experimental results obtained for the sextuple Brillouin Stokes line (0.48 nm) based on stimulated Brillouin scattering phenomenon are presented in this paper. Three ring laser cavities with unidirectional propagation are used. In each ring cavity, a dispersion compensation fibre (DCF) spool is used as a Brillouin gain medium. Two erbium amplifiers are used to amplify the generated Stokes signal and to overcome the path loss for the propagation Stokes lines. A maximum pump power of 500 mW at a central wavelength of 1480 nm is used for these two amplifiers. In our new structure, up to three sextuple Stokes lines with a high signal power of 10 dBm and a large optical signal-to-noise ratio of more than 55 dB are achieved. The generated Stokes lines can be tuned over a wavelength range of 15 nm from 1560 to 1575 nm. [ABSTRACT FROM AUTHOR]

Optical up-conversion photonic Doppler velocimetry (PDV) based on stimulated Brillouin Scattering (SBS) with an all-fiber link structure is proposed in this article. Because SBS limits the laser power transmitted by a fiber over long distances, the probe does not have enough outgoing light to reach the measured surface and cannot receive the signal light. Traditionally, SBS is avoided, but it is a phase-conjugated light and shifts down relative to the source light, so it can be used as a reference light in the laser interference structure to achieve up-conversion heterodyne velocimetry. Compared with general homodyne velocimetry (DPS), SBS-PDV naturally upconverts and has more interference fringes and higher resolution at low-speed measurement. In the gas multiple reflection impact compression experiment, the velocity measurement results of SBS-PDV and dual-laser heterodyne Velocimetry (DLHV) are basically consistent, and the accuracy is better than 0.8%. Due to its coaxial heterodyne optical path, this kind of photonic Doppler velocimetry is suitable for low-velocity and long-distance practical applications in the field of shock wave physics.

This paper investigated the temporal behavior of the backward Stokes pulse from a stimulated Brillouin scattering phase conjugate mirror (SBS_PCM) in a pure acetone medium. Changes in the reflected energy of the phase-conjugate mirror and the temporal width of the Stokes pulse due to changes in the input energy flux to the cell and changes in the interaction length were studied for the single-cell structure. For this purpose, to achieve the optimal optical arrangement for maximum efficiency and minimum pulse width in full width half maximum, the cell length and the geometric structure of the phase conjugate mirror have been changed. Variations of the energy and the reflected Stokes pulse width of the phase conjugate mirror were compared for the considered cases. The results show that the reflected energy of the phase conjugate mirror can be optimized by changing the interaction geometry. By increasing the intensity of the input beam at constant energy and changing the interaction length, the minimum reflected pulse width was achieved in terms of input energy.

In this work, an all-fiberized polarization-maintained (PM) fiber laser has been demonstrated with a near-top-hat-shaped spectrum. By optimizing the modulation signal to generate near-top-hat-shaped spectrums, a 3-kW PM fiber laser has been achieved at

An experimental study of a tunable 60 GHz multiwavelength Brillouin erbium fiber laser is presented in this paper. Two unidirectional ring laser cavities and two pre-amplification laser cavities are used. In the first three cavities, a Brillouin gain medium is presented with a dispersion compensation fiber (DCF) spool, and a single-mode fiber (SMF) spool is used as a Brillouin gain medium in the fourth cavity. Three erbium amplifiers are utilized to supply enough gain to the generated Brillouin Stokes signal and to suppress cavity losses. For these three amplifiers, up to 450 mW (150 mW for each) of a 1480 nm pump power is used. In our proposed configuration, four sextuple Brillouin Stokes signals with a high power of 10 dBm and more than 55 dB as an optical signal-to-noise ratio are achieved. The obtained Brillouin Stokes signals can be tuned over 30 nm (1560–1590 nm) and can be easily used in dense wavelength division multiplexing in optics communication systems. [ABSTRACT FROM AUTHOR]

Stimulated Brillouin scattering (SBS) is the major factor that limits the maximum optical fiber output power in narrow linewidth applications, which include important fields such as passive optical networks (PONs), high-power fiber amplifiers, and lasers. Great efforts have been dedicated to suppressing the SBS effect and increasing the maximum optical fiber output power. This paper focuses on key fiber-based techniques to suppress SBS. These techniques take advantages of the properties of optical fibers. We present how these properties (electric modes, acoustic modes, and material properties) could be utilized to suppress SBS. The fiber-based techniques are divided into transverse optical fiber design, longitudinal variant fiber design, and external perturbations (strain and temperature) on optical fibers. Transverse optical fiber design focuses on the mechanism electro-acoustic interaction. Large effective area fiber design and acoustic tailoring techniques have been discussed. Longitudinal variant fiber design considers the nonlinear SBS interaction along propagation distance, and various techniques related have been presented. External perturbations (strain and temperature) on optical fibers emphasize on how external static perturbations could modify the SBS effect. [ABSTRACT FROM AUTHOR]

A multimode optical fiber supports excitation and propagation of a pure single optical mode, i.e., the field pattern that satisfies the boundary conditions and does not change along the fiber. When two counterpropagating pure optical modes are excited, they could interact through the stimulated Brillouin scattering (SBS) process. Here, we present a simple theoretical formalism describing SBS interaction between two individual optical modes selectively excited in an acoustically isotropic multimode optical fiber. Employing a weakly guiding step-index fiber approach, we have built an analytical expression for the spatial distribution of the sound field amplitude in the fiber core and explored the features of SBS gain spectra, describing the interaction between modes of different orders. In this way, we give a clear insight into the sound propagation effects accompanying SBS in multimode optical fibers, and demonstrate their specific contributions to the SBS gain spectrum. [ABSTRACT FROM AUTHOR]

Novel techniques of photonics based on stimulated Brillouin scattering (SBS) in optical fibers are considered. The main attention is paid to the original schemes of narrow-band low-noise lasers and their possible applications in distributed fiber sensors. [ABSTRACT FROM AUTHOR]

Co-transmission of optically-carried broadband wireless communication signal and power light in standard single-mode fiber (SSMF) is the supporting technology for realizing remotely-powered antenna units in the next-generation wireless communication networks. Here, we experimentally demonstrate the co-transmission of optically-carried fifth-generation new radio (5G NR) signal and over 14-W power light via a spool of SSMF with a length of 1 km. Thereinto, the optical power transmission efficiency (OPTE), which is restricted by stimulated Brillouin scattering, is increased via extending the linewidth of the power light to 1 nm. Additionally, the in-band interference and the signal-to-noise ratio (SNR) degradation of the optically-carried 5G NR signal, which are attributed to the noise transference and the modulation instability induced by the Kerr effect and the stimulated Raman scattering effect, are suppressed through group-velocity dispersion management via carefully designing the wavelengths of the signal light and the power light. In the simulation, a 7-dB reduction in the noise floor and a significant rejection of the spurious signals are achieved via shifting the signal light wavelength from 1550 nm to 1310 nm. In the experiment, the OPTE of the power light reaches around 70%, and the received power fluctuation is smaller than 1% within 90 min. The received maximum electrical power is larger than 0.9 W with a regulated voltage of 12 V, which is sufficient to power the minimalist antenna unit. Besides, the error vector magnitude (EVM) and the adjacent channel leakage ratio (ACLR) of the received 256-level quadrature amplitude modulation (256-QAM) 5G NR signal are below 2.5% and −40 dBc, respectively. The experimental results conclusively demonstrate the feasibility of the co-transmission link to enable remote power supply for the minimalist antenna unit in the beyond fifth-generation and sixth-generation fronthaul networks. [ABSTRACT FROM AUTHOR]

A versatile angled fiber coupling platform for magnesium fluoride whispering gallery mode resonators is used to investigate nonlinear frequency conversion across 1.5 and 2 μ m bands. We characterize MgF 2 microcavities of varying sizes (4.3 mm, 1.9 mm, and 0.73 mm in diameter), achieving quality factors up to 2 × 1 0 9 at 1. 55 μ m and 5 × 1 0 8 at 1. 94 μ m. In the telecom regime, we observe rich nonlinear phenomena including Kerr comb generation, Brillouin lasing, and Raman lasing. Extending to the 2 μ m band, we demonstrate four-wave mixing in a sub-millimeter cavity, highlighting the platform's potential for the 2 μ m band mid-infrared nonlinear optics. [Display omitted] • Angled fiber coupling enables nonlinear optics in MgF 2 cavities at 1. 5 μ m and 2 μ m. • Kerr comb, Brillouin and Raman lasing observed in 730 μ m MgF 2 cavity at 1. 5 μ m. • Report of four-wave mixing in 730 μ m MgF 2 microcavity at 2 μ m wavelength. [ABSTRACT FROM AUTHOR]

The leading-edge based stimulated Brillouin scattering (SBS) pulse compression technology is increasingly being recognized as a significant advancement for the generation of high-energy short-pulse lasers. Trailing-edge based laser-induced breakdown (LIB) compression is anticipated to be an effective supplement to SBS, helping to overcome its compression limitations. In this study, we integrated SBS and LIB to generate a high-power, short-pulse laser, thereby surpassing the compression constraints of SBS. Furthermore, we enhanced LIB by doping the LIB medium with α-Al 2 O 3 nanosheets obtained through molten salt synthesis. As a result, we have successfully compressed the pulse duration from 8ns to 241ps, achieving relatively symmetrical leading and trailing edges. Moreover, compared to pure water, we obtained a higher quality far-field light spot. • Cascading SBS and LIB for pulse compression. • Enhancing the LIB process through thermal effects. • Fabricating doped α-Al 2 O 3 nanosheets to enhance the LIB process. • Improved the far-field distribution of the beam. • Obtained laser output with a shorter pulse duration. [ABSTRACT FROM AUTHOR]

A pulse duration compression technique that combines stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS) was presented in this study, achieving an output pulse duration of 48.3 ps. The feasibility of this approach has been experimentally demonstrated. To be specific, a pulse duration of 7.4 ns is compressed to 48.3 ps with an energy of 5.27 mJ, and the energy efficiency of the SRS pulse duration compression system is up to 21.84%. Moreover, this study provides a practical method for reliably generating high-energy short pulses.

Stimulated Brillouin scattering (SBS) microscopy is a nonlinear all-optical imaging method that provides mechanical contrast based on the interaction of laser radiation and acoustical vibrational modes. Featuring high mechanical specificity and sensitivity, three-dimensional sectioning, and practical imaging times, SBS microscopy with (quasi) continuous wave excitation is rapidly advancing as a promising imaging tool for label-free visualization of viscoelastic information of materials and living biological systems. In this article, we introduce the theory of SBS microscopy and review the current state-of-the-art as well as recent innovations, including different approaches to system designs and data analysis. In particular, various performance parameters of SBS microscopy and its applications in the life sciences are described and discussed. Future perspectives for SBS microscopy are also presented.

A mechanism coupling the stimulated Brillouin scattering (SBS) of two-color lasers with wavelengths of 527 and 351 $\mathrm{nm}$ via the two-ion decay instability is proposed. When the SBS reflectivities of both lasers exceed 10%, the ion-acoustic wave excited by the 527 $\mathrm{nm}$ laser seeds the decay process of the ion-acoustic wave excited by the 351 $\mathrm{nm}$ laser, thereby promoting the decay of the latter into the former. This results in a significant reduction in the SBS reflectivity of the 351 $\mathrm{nm}$ laser, while the SBS of the 527 $\mathrm{nm}$ laser exhibits minimal variation, consequently reducing the total SBS reflectivity. The total SBS reflectivity initially decreases and then increases as the intensity fraction α of the 527 $\mathrm{nm}$ laser rises. When $\alpha \sim (20\%{-}30\%)$ , the laser energy reflections from both lasers become approximately equal, achieving the minimum total reflectivity. Through this mechanism, the incidence of the two-color lasers can achieve lower reflected energy compared to monochromatic lasers with the same total intensity. These results demonstrate the significant potential of replacing a small fraction of high-frequency light with low-frequency light in enhancing the laser-target coupling efficiency for inertial fusion energy.

Fiber optic parametric and phase sensitive amplifiers (PSA) are interesting for modern day communication technologies due to their low noise and high gain amplification properties with a potential for all optical signal processing and wide band operation. PSAs are typically employed in either a single pump or dual pump configuration. In this article we explore the utilities of both configurations, however considering a fiber with a longitudinally varying dispersion profile. For the single pump case, PSA operation at large pump-signal detunings, that arise due to the longitudinal dispersion variation, were studied numerically, and recipes of using the system as a wide band wavelength selective filter were laid out. For the dual-pump case, emphasis was laid on achieving a larger signal gain, by reducing stimulated Brillouin scattering (SBS) that prevents large pump power transport through the nonlinear fiber. First, the effects of dispersion variation on the gain of a dual pump PSA were studied analytically and numerically in order to optimize the dispersion variation profile, neglecting SBS processes. Then we independently studied the SBS dynamics of the system numerically. A sinusoidally dispersion oscillating fiber (DOF) was found to be an optimal candidate with respect to its PSA and SBS performances. To establish this claim, we also experimentally compared the performance of an available DOF over a standard highly nonlinear fiber (HNLF) that has a constant dispersion profile and established its utility for designing a high gain PSA system, thanks to the SBS mitigation due to the longitudinal dispersion variation of the fiber.

We have demonstrated a simple all-fiber thulium (Tm) laser Q-switched by stimulated Brillouin scattering (SBS). The maximum output pulse energy was 80 μJ. This allowed us to generate a broadband spectrum directly at the laser outputs. For the first time, we measured the fine structure of the output pulses with a resolution of less than 100 ps. It was found that the SBS Q-switched laser is capable of generating bunches of picosecond pulses. The effect of modulation instability on the pulse decay is discussed. The potential application of the investigated laser radiation for producing destructive effects on soft biological tissues has been demonstrated.

To optimize the output of SBS sub-nanosecond pulse compression, two kinds of compact double-cell structures are carried out and compared experimentally. The beam parameters of the compact double-cell structure are calculated theoretically, which provides the selection guidance of structural parameters such as lens focal length and SBS cell size. The dependence of lens parameters and medium parameters on SBS output parameters are experimentally studied. Results show that SBS pulse compression enters the saturation region at a low injection energy with a long focal length lens or a large gain coefficient medium. For compact double-cell setup with one lens, it is easy to obtain narrow pulses for the medium FC40 with a short phonon lifetime. While in setup with two lenses, it is easy to obtain SBS output with a high energy efficiency and narrow pulse width for HT110 medium with a large gain coefficient. The pulse width compression ratio is up to 16 times after optimization. These experimental results can provide references for the experimental design of SBS pulse compression.

Brillouin microscopy based on spontaneous Brillouin scattering has emerged as a unique elastography technique because of its merit of non-contact, label-free, and high-resolution mechanical imaging of biological cell and tissue. Recently, several new optical modalities based on stimulated Brillouin scattering have been developed for biomechanical research. As the scattering efficiency of the stimulated process is much higher than its counterpart in the spontaneous process, stimulated Brillouin-based methods have the potential to significantly improve the speed and spectral resolution of existing Brillouin microscopy. Here, we review the ongoing technological advancements of three methods, including continuous wave stimulated Brillouin microscopy, impulsive stimulated Brillouin microscopy, and laser-induced picosecond ultrasonics. We describe the physical principle, the representative instrumentation, and biological application of each method. We further discuss the current limitations as well as the challenges for translating these methods into a visible biomedical instrument for biophysics and mechanobiology.