High Stimulated Brillouin Scattering Threshold Research Articles

Spectral broadening scheme for suppressing SBS effects based on time-domain optimized chirp-like signals.

We propose a novel (to our knowledge) driving scheme to suppress the stimulated Brillouin scattering (SBS) effect in master oscillator power amplification (MOPA) systems based on an external high-order phase modulation. Since seed sources with the linear chirp can uniformly broaden the SBS gain spectrum with a high SBS threshold, a chirp-like signal was designed by applying further editing and processing to the piecewise parabolic signal. Compared with the traditional piecewise parabolic signal, the chirp-like signal has similar linear chirp characteristics and can reduce the driving power and sampling rate requirements, enabling more efficient spectral spreading. The SBS threshold model is constructed theoretically based on the three-wave coupling equation. The spectrum modulated by the chirp-like signal is compared with the flat-top and Gaussian spectra in terms of the SBS threshold and the bandwidth-distribution normalized threshold, and a considerable improvement is demonstrated. Meanwhile, the experimental validation is carried out in a watt-class amplifier based on the MOPA structure. At a 3 dB bandwidth of ∼10 GHz, the SBS threshold of the seed source modulated by the chirp-like signal is improved by 35% compared to the flat-top spectrum and 18% compared to the Gaussian spectrum, respectively, and the normalized threshold is also the highest among them. Our study shows that the SBS suppression effect is not only related to the power distribution of the spectrum but also can be improved by the time domain design, which provides a new idea for analyzing and improving the SBS threshold of narrow-linewidth fiber lasers.

Performance enhancement of BOTDR fiber optic sensor for oil and gas pipeline monitoring

Abstract Distributed fiber optic sensor which based on Brillouin scattering has become increasingly popular due to its unprecedented advantage of simultaneously measuring temperature and strain. The Stimulated Brillouin Scattering (SBS) threshold, sensing distance, signal-to-noise ratio and spatial resolution are critical parameters to the performance of Brillouin Optical Time Domain Reflectometry (BOTDR) sensor. This technical paper presents the result of simulations as well as theoretical discussions on suppressing unfavorable fiber optic nonlinearity, SBS by using a statistical approach which is design of experiment (DOE). Due to the fact that there are a number of SBS threshold factors, there is a high possibility that multiple strong interactions exist among these factors. Conventional methods of plugging each factor one-at-a-time are not efficient as interactions between factors are totally ignored. The result had shown SBS suppression by 11 dB to achieve the maximum sensing distance of up to 110 km. Besides, a 3-bit simplex coding is employed when launching the laser pulses to enhance the SNR at the receiver. Simulation results demonstrated a 1.38 gain in SNR and a higher SBS threshold.

Al/Ge co-doped large mode area fiber with high SBS threshold

We propose a novel approach of making large effective area laser fiber with higher threshold for the stimulated Brillouin scattering (SBS) using Al/Ge co-doping in the fiber core. The increased SBS threshold is achieved by reducing the acoustic-optic overlap integral while keeping the optical refractive index profile with a step structure. The manipulation of the overlap integral is done by adjusting the relative doping level between Al(2)O(3) and GeO(2) in the core. The mechanism is validated by detailed examples of numerical modeling. An Yb-doped double clad fiber with the core co-doped with Al(2)O(3) and GeO(2) was fabricated by the OVD process. Measured acoustic velocity profile using a scanning acoustic microscope verified that the acoustic velocity in the fiber core changes with the design. An amplifier utilizing the fiber demonstrated that the proposed fiber yielded 6 dB higher SBS threshold than a fiber without using the co-doping scheme.

Bismuth-oxide-based nonlinear fiber with a high SBS threshold and its application to four-wave-mixing wavelength conversion using a pure continuous-wave pump

The unique and practical benefits of the use of bismuth-oxide-based nonlinear fiber (Bi-NLF) in implementing a four-wave-mixing (FWM)-based wavelength converter for fiber-optic-communication-system applications are experimentally demonstrated. First, the Kerr-nonlinearity and stimulated-Brillouin-scattering (SBS) characteristics of our fabricated Bi-NLF are experimentally investigated. The Bi-NLF is found to have the superior advantage of a significantly high SBS threshold in addition to its ultrahigh Kerr nonlinearity /spl gamma/ of /spl sim/1100 W/sup -1//spl middot/km/sup -1/, compared to the conventional silica-based highly nonlinear fiber. Next, the authors perform an experiment for the FWM-based wavelength conversion of a non-return-to-zero (NRZ) signal within a 40-cm length of the Bi-NLF fusion spliced to standard silica fibers by using a continuous-wave (CW) high-power pump beam. Error-free tunable wavelength conversion over a 10-nm bandwidth is readily achieved. No SBS-suppression scheme is employed for the pump due to the high SBS threshold, which simplifies the system configuration and improves the quality of the wavelength-converted signal.

Bismuth nonlinear fibre-based optical phase conjugator without SBS-induced efficiency limitation and its application to dispersion compensation in transmission link

The implementation of a stimulated Brillouin scattering (SBS) free, optical fibre phase conjugator by use of only 1 m length of fabricated bismuth oxide-based nonlinear fibre (Bi-NLF), has been experimentally demonstrated. A high OSNR phase-conjugated signal was readily achieved owing to the unique properties of the Bi-NLF such as an ultra-high χ(3) nonlinearity and a high SBS threshold although no SBS suppression scheme was employed. Using the phase conjugator, error-free transmission of the signal is readily achieved over a 150 km SMF link.

Techno-economic study of the value of high stimulated Brillouin scattering threshold single-mode fiber utilization in fiber-to-the-home access networks

Cost modeling reveals that deployment of fibers with a high stimulated Brillouin scattering threshold in fiber-to-the-home access networks can reduce material and labor expenditures by more than 20%. Theory and measurements of the high stimulated Brillouin scattering fiber are presented to demonstrate its employability.

Wide-band tunable wavelength conversion of 10-gb/s nonreturn-to-zero signal using cross-phase-Modulation-induced polarization rotation in 1-m bismuth oxide-based nonlinear optical fiber

We experimentally demonstrate that the use of only 1-m length of our fabricated Bismuth oxide-based nonlinear fiber readily allows for implementing a high-performance 10-Gb/s nonreturn-to-zero signal wavelength converter based on cross-phase-modulation-induced polarization rotation. No stimulated Brillouin scattering (SBS) suppression scheme was employed owing to a high SBS threshold of the fiber. Our wavelength converter is shown to provide a pattern-inverted or a noninverted output signal in the same configuration depending on the relative polarization directions between the probe and the polarizer. Error-free wavelength conversion over a 30-nm bandwidth is readily achieved for both cases, i.e., noninverted and inverted patterns.

Four-wave-mixing-based wavelength conversion of 40-Gb/s nonreturn-to-zero signal using 40-cm bismuth oxide nonlinear optical fiber

We experimentally demonstrate a compact and tunable four-wave-mixing-based wavelength converter using a Bi/sub 2/O/sub 3/-based nonlinear fiber (Bi-NLF). An only 40-cm-long Bi-NLF is used as a nonlinear optical medium for wavelength conversion of a 40-Gb/s nonreturn-to-zero (NRZ) signal with no additional stimulated Brillouin scattering (SBS) suppression scheme. The Bi-NLF used in this experiment has an extremely high SBS threshold owing to both its short length and relatively low Brillouin gain. The 40-cm Bi-NLF is fusion-spliced to standard single-mode fibers and its nonlinearity is measured to be /spl sim/1100 W/sup -1//spl middot/km/sup -1/. Error-free wavelength conversion over a 10-nm bandwidth at a 40-Gb/s NRZ data rate is readily achieved with a pure continuous-wave pump.

Four-wave mixing based 10-Gb/s tunable wavelength conversion using a holey fiber with a high SBS threshold

We demonstrate a four-wave-mixing based wavelength converter using a 15-m highly nonlinear holey fiber (HF) with a high stimulated Brillouin scattering (SBS) threshold. Error-free efficient wavelength conversion of 10-Gb/s nonreturn-to-zero signal over a /spl sim/10-nm bandwidth is reliably achieved. Our 15-m HF has a nonlinearity coefficient /spl gamma//spl sim/70(/spl plusmn/10) W/sup -1//spl middot/km/sup -1/ and an SBS threshold of more than 130 mW. The high SBS threshold is achieved by applying structural variation to the HF along its length during the fabrication process. No modulational-instability-induced intensity noise on the converted signals is observed due to the normal dispersion of the HF.