Stimulated Brillouin Scattering System Research Articles

Optical Generation of 80 GHz Downstream Data in Radio over Fiber System Based on Stimulated Brillouin Scattering

In this work, we proposed Stimulated Brillouin Scattering (SBS) in an optical generation of millimeter waves (mm-waves) for radio over fiber (RoF) system with the transmission of 2.5 Gbps data rate. SBS method is achieved by imposing continuous wave (CW) laser in a single mode optical fiber (SMF) via Mach-Zehnder Modulator (MZM) with Erbium-Doped Fiber Amplifier (EDFA) and two pump lasers. Mm-waves signal of 80 GHz was generated from a 40 GHz radio frequency (RF) synthesizer. Simulation result and the analysis comparison of effective light power are investigated with different SMF loop length from 20 km until 120 km. The performance of SBS system is analysed and the generated of millimeter waves signal can be transmit with length up to 120 km based on eye pattern and Bit Error Rate (BER) curve.

Microresonator Brillouin laser stabilization using a microfabricated rubidium cell.

We frequency stabilize the output of a miniature stimulated Brillouin scattering (SBS) laser to rubidium atoms in a microfabricated cell to realize a laser system with frequency stability at the 10-11 level over seven decades in averaging time. In addition, our system has the advantages of robustness, low cost and the potential for integration that would lead to still further miniaturization. The SBS laser operating at 1560 nm exhibits a spectral linewidth of 820 Hz, but its frequency drifts over a few MHz on the 1 hour timescale. By locking the second harmonic of the SBS laser to the Rb reference, we reduce this drift by a factor of 103 to the level of a few kHz over the course of an hour. For our combined SBS and Rb laser system, we measure a frequency noise of 4 × 104 Hz2/Hz at 10 Hz offset frequency which rapidly rolls off to a level of 0.2 Hz2/Hz at 100 kHz offset. The corresponding Allan deviation is ≤2 × 10-11 for averaging times spanning 10-4 to 103 s. By optically dividing the signal of the laser down to microwave frequencies, we generate an RF signal at 2 GHz with phase noise at the level of -76 dBc/Hz and -140 dBc/Hz at offset frequencies of 10 Hz and 10 kHz, respectively.

Intense spikes formed in a feedback stimulated Brillouin scattering system

Intense spikes were experimentally and numerically studied in a feedback stimulated Brillouin scattering (SBS) system. By modulating the input pump wave with a low frequency (100kHz) signal, the intense spikes are shown to appear rarely and randomly. Specifically, the experimental results indicate that the probability density function (PDF) is characterized by the L-shaped distribution. Theoretical simulations based on the three-wave parametric coupling model of the SBS system show a good consistency with the experimental results.

Broadening-free stimulated Brillouin scattering-based slow and fast light in optical fibers

The manipulation of the group velocity of optical signals (slow and fast light) has many possible applications in telecommunications, sensing, nonlinear optics, and so on. The exploitation of the effect of stimulated Brillouin scattering (SBS) is of special interest for the alteration of the group velocity in optical fibers, since it just requires standard telecom equipment and low-to-moderate optical power. However, each delay in one single, low-gain SBS-based slow-light system is accompanied by a pulse broadening. This is a result of the inherent Kramers–Kronig relations among the gain, the phase change, and the accompanied group velocity. For an ideal flat gain, the phase change is nonideal, and for an ideal phase change the gain curve leads to a broadening. Furthermore, if the gain bandwidth is adapted to the signal by broadening, the delay will be reduced. Thus the signal broadening can be reduced by several methods for one single low-gain slow-light system, but it cannot be zero. Here, we will show how a zero-broadening SBS-based slow light can be achieved with several methods. The basic idea is a reshaping of the original pulse in a second stage by saturation of the SBS system, or by the superposition of two gains. As will be shown, all of these systems show an almost ideal overall gain and phase function over the bandwidth of the pulses. Thus, SBS-based slow light with a delay bandwidth product of 1 bit and zero distortion is possible.

A Study of the Linearity Performance of a Stimulated Brillouin Scattering-Based Microwave Photonic Bandpass Filter

The linearity of stimulated Brillouin scattering (SBS) is studied in detail for the first time. A closed-form expression which measures the linearity of an SBS system is derived. This expression allows one to design the region of linear operation, and the amount of Brillouin gain of an SBS system, by altering some basic system parameters. The theory presented is experimentally verified using an SBS-based microwave photonic filter structure. The effect of the length of the Brillouin medium on the linearity of the filter is investigated, and a 9.7 dB extension in the dynamic range is demonstrated by reducing the length of the fibre used as the Brillouin medium, from 25 to 0.57 km, while the filter stopband rejection level remains 30 dB.

Extended chaotic domain in the long optical fibers based on SBS process

Chaotic stimulated Brillouin scattering (SBS) in optical fibers with weak external optical feedback has been investigated experimentally and theoretically. However, only the bifurcation route to chaos through period-one and quasi-periodic emission was discovered in the former work because the chaotic domain is very short in the general nonlinear system. In order to control the chaos process and observe finer periodic-orbit structures, a novel experiment was designed to extend the chaotic domain by using long optical fibers in the SBS system. In this experiment, the period-one, period-doubling, period-four and period-eight cycle routes to the chaos laser process as well as the more details of chaos, have been observed.

Research on the SBS mediums used in high peak power laser system and their selection principle

AbstractIn this paper, we designed an experiment to research the properties for the stimulated Brillouin scattering (SBS) medium of perfluorocarbon-compounds (PFCs) and perfluoropolyether (PFPE), then we proposed that the selection principle of the high load capacity SBS medium can be used in the high peak power SBS system. The results showed that, for PFCs, perfluorinated hydrocarbons (FC-72) has the highest optical breakdown threshold (OBT); for PFPE, the medium with average molecular weight (AMW) less than 1000 has small medium absorption coefficient (AC) and high OBT, for AMW, greater than 1000, the medium AC becomes high and the OBT becomes low. Further research shows that, for PFPE series SBS medium, the AC increases and the OBT decreases gradually with increasing of AMW. We find some SBS mediums can work stably under high peak power pump, which lays a good foundation for the application of SBS technology in a high-power laser system.

The effects of medium phonon lifetime on pulse compression ratio in the process of stimulated Brillouin scattering

The performances of stimulated Brillouin scattering (SBS) media with short phonon lifetimes on temporal compression are studied in this paper. In the experiment, FC-72, HT-135 and FC-40 (phonon lifetimes are 1.2ns, 0.4ns and 0.2ns, respectively) are used to study the influence of phonon lifetime on pulse compression in a compact two-cell SBS system. High pulse compression ratio is obtained by a medium with a short phonon lifetime when input energy is high. These results are useful in the generation of picoseconds pulse for Shock Ignition of thermonuclear fuel for ICF.

Systematic design study of an all-optical delay line based on Brillouin scattering enhancedcascade coupled ring resonators

We present a technique to improve the slow-light performance of a side-coupled integratedspaced sequence of resonators (SCISSOR) combined with a stimulated Brillouin scattering (SBS)gain medium in optical fibers. We evaluate device performance of SCISSOR-only andSCISSOR + SBS systems for different numbers of cascaded resonators from 1 to 70 using two different datafidelity metrics including eye-opening and mutual information. A practical system design isdemonstrated by analyzing its performance in terms of fractional delay, power transmission,and data fidelity. We observe that the results from the two metrics are in good agreement.Based on system optimization under practical resource and fidelity constraints,the SCISSOR consisting of 70 cascaded resonators provides a fractional delay of ∼ 8 with 22 dB attenuation at a signal bit rate of 10 Gbps. The combined optimal SCISSOR(with 70 resonators) + SBS system provides a improved fractional delay up to ∼ 17 with unit power transmission under the same constraints.

Investigation on stimulated Brillouin scattering medium——perfluoropolyether at high and low temperatures

In this paper, the stimulated Brillouin scattering (SBS) media perfluoropolyether (PFPE) with unique physicochemical properties and SBS properties are researched. The PFPE has a small absorption coefficient and can be used to increase the load-ability of SBS system. The PFPE with a high boiling point and a low pouring point can operate at high and low temperatures, respectively. The SBS properties of PFPE have been analyzed in detail and validated in Q-switched Nd:YAG laser system. The experimental results indicate that the media not only have good SBS characteristics but also can be used in a wide temperature range, thereby has great advantage for experimental investigation on SBS phase-conjugated mirror at different temperatures.

Improved slow-light delay performance of a broadband stimulated Brillouin scattering system using fiber Bragg gratings

We present a technique for improving the pulse-delay performance of a stimulated Brillouin scattering (SBS) based broadband slow-light system by combining it with fiber Bragg gratings (FBG). We optimize the physical device parameters of three systems: (1) broadband SBS, (2) broadband SBS + a single FBG, and (3) broadband SBS + a double FBG for maximizing the delay performance. The optimization is performed under distortion and system resource constraints for a range of bit rates from 0.5 to 8.5 Gbps. We find that an optimized broadband SBS + a double FBG system improves the fractional delay 1.8 times that of the broadband SBS system at an optimum bit rate of 3 Gbps. Also, pump power consumption is reduced by 15% as compared to the broadband SBS system at the same bit rate.

Investigation of stimulated Brillouin scattering media perfluoro-compound and perfluoropolyether with a low absorption coefficient and high power-load ability

The correlations between stimulated Brillouin scattering (SBS) characteristics of perfluoro-compound (PFC) and perfluoropolyether (PFPE) and their chemical structure are analyzed in detail and a series of new PFC and PFPE are reported. In the Nd:YAG laser system, the absorption coefficient, optical breakdown threshold (OBT), SBS threshold, and Brillouin frequency shift of new media such as FC-87, FC-43, HT-55, and DET are measured. Parameters such as gain coefficient, Brillouin linewidth, and phonon lifetime are calculated. The results demonstrate their good SBS properties: the absorption coefficients are below 10(-3)cm(-1) and OBTs are above 100 GW/cm(2). These media also exhibit a series of unique physicochemical properties, i.e., high heat-resistance, high oxidation stability, good chemical inertness, and insulation properties. The discovery of new media not only diversifies SBS medium, but also improves the performance of the SBS system, thereby laying a good foundation for the application of a SBS phase conjugation mirror in a high-power laser system.

New SBS media——perfluorinated amines

The stimulated Brillouin scattering (SBS) media perfluorinated amines with good SBS characteristics have been discovered based on the dependence of SBS characteristics on the chemical structures. The SBS parameters of perfluorinated amines such as FC-131, FC-3283, FC-40, FC-43 and FC-70 have been measured or calculated. The results demonstrate that their absorption coefficients are below 10-3cm-1 and optical breakdown thresholds are above 100GW/cm2. The perfluorinated amines also exhibit a series of unique physicochemical properties, i.e., non-toxic property, low volatility, and high stability. The discovery not only diversifies the SBS media, but also improves the performance of SBS system, thereby laying a good foundation for the application of SBS phase conjugation mirror in high-power laser systems.

Research on the enhancement of power-load of two-cell SBS system by choosing different media or mixture medium

In order to enhance the power-load of two-cell stimulated Brillouin scattering (SBS) system, methods of using different media and mixed medium are proposed. In theory, the amplification function of two-cell system of different medium with close vicinity in the Brillouin frequency shift (BFS) is analyzed. Also the variation of BFS of the mixed medium with the mixing ratio is analyzed. In the two-cell SBS system pumped by Q-switched Nd:YAG laser, the SBS system performance characteristics are investigated with different media and mixed medium. The experimental results indicate that the Stokes can be sufficiently amplified by choosing different medium with close vicinity in the BFS; the power-load performance is enhanced as well as the maximum amplification efficiency the Stokes by choosing mixed medium.

Investigation on improving characteristics of two-cell SBS system with CCl 4 /C 2 H 5 OH liquid mixture

In order to improve the performance of the two-cell stimulated Brillouin scattering (SBS) system, this paper proposes the methods of using mixtures, which require amplifier media to have small absorption rate, and generator media to have high optical breakdown threshold and Brillouin frequency shift equal to that of the amplification media. The characteristics of the two-cell SBS system are studied experimentally by using CCl4 as amplifier medium and CCl4, C2H5OH and CCl4/C2H5OH liquid mixture as generator medium pumped by Nd:YAG Q-switched laser. The obtained results show that liquid mixture in generator cell improves the power load ability, phase conjugation fidelity, energy reflectivity (ER) and ER stability.

Study on two-cell stimulated Brillouin scattering system with mixture medium

In this paper, a method of choosing mixture medium in two-cell stimulated Brillouin scattering (SBS) system to improve the system performance is proposed. The Brillouin frequency shift (BFS) of mixture medium varies with the mixing ratio and thus the difference of the BFS between the two cells can be eliminated. The two-cell SBS system with acetone (C3H6O) in its generator cell and mixture liquid of CCl4/C2Cl4 in its amplifier cell is investigated. The C3H6O has a high optical breakdown threshold and the mixture liquid of CCl4/C2Cl4 has a small absorption coefficient and the same BFS as that of C3H6O when the volume fraction of CCl4 is 4%. Compared with two-cell SBS system with the same liquid (C2Cl4) or different liquid (C3H6O and C2Cl4) in generator and amplifier cell, the SBS system with mixture liquid (CCl4/C2Cl4) in amplifier cell and C3H6O in generator cell improves the power-load, energy reflectivity (ER), phase conjugation (PC) fidelity and ER stability.

Study on two-cell stimulated Brillouin scattering system with new media

According to the relationships between the chemical structure of the medium and the absorption coefficient, a series of new media with small absorption coefficients has been found, which are suited for use as the amplifier media. The stimulated Brillouin scattering (SBS) parameters of these media have been calculated or measured when the pump wavelength is 1.064 μm. Choosing C2Cl4 and C4Cl6 as amplifier medium and C2H5OH as generator medium, we investigated the performances of two-cell SBS system pumped by Nd:YAG Q-switched laser. The C2H5OH has a high optical breakdown threshold and the Brillouin frequency shift of C2H5OH is close to those of C2Cl4 and C4Cl6. The results indicate that the system has the characteristics of high power-load ability, high phase-conjugation fidelity and high energy reflectivity stability.

Study on Brillouin amplification in different liquid media

The two_cell stimulated Brillouin scattering (SBS) system that uses different media in generator and amplifier cells is investigated. It is demonstrated that th e seed light still has enough amplification when the Brillouin frequency shifts of this two media are near and their Brillouin line_widths are crossed. In exper iment, when CCl4 is used as an amplifying medium and liquid mixture of CCl4/ CS2 as generating medium, and the two_cell SBS system is pumped by Nd:YAG Qs witched laser, the influence of the deviation of Brillouin frequency shift on seed light Brillouin amplification is studied. The result shows that amplification efficiency and pulse compression ratio are still large enough when Brillouin frequency deviation is small. Moreover, under the condition of CS2 as the amplifying medium and benzene as the generating medium, seed light amplification efficiency of 44, pulse compression ratio of 72, phase_conjugation fidelity of 98%, and stability of seed light amplification efficiency of <3% are obtaine d.

Analytical Calculation of Stimulated Brillouin Scattering in Magnetic Fields Applied to n-InSb

For the study of parametric excitation, we have considered that the origin of Stimulated Brillouin Scattering (SBS) nonlinear interaction lies in the third-order optical susceptibility in a centrosymmetric, doped semiconductor which is subjected to transverse magnetic field. The third-order optical polarization in a SBS system arises due to nonlinear current density and acousto-optical strain of the medium. The displacement of lattice motion and threshold expressions are determined and conditions for the onset of the SBS are obtained. The induced acousto-optical polarization and effective Brillouin polarization are determined using a coupled mode scheme. Using the effective Brillouin polarization so achieved, the transmitted intensity and efficiency of the Brillouin cell have also been calculated. The effect of wave number, electric field, doping and magnetic field on different parameters is also studied and numerical estimations are made for n-InSb at 77 K duly shined by a pulsed 10.6 μm CO2 laser. The lattice displacement is significantly enhanced by wave vector, electric field and transverse magnetostatic field. It is observed that the acousto-optical polarization increases with magnetic field while the nonlinear induced polarization decreases. The effective Brillouin polarization increases with wave number, electric field amplitude and magnetic field which is required to achieve an optical-phase-conjugation process.