A. Boh Ruffin

Design concept for optical fibers with enhanced SBS threshold

We propose a criterion to predict the relative value of the stimulated Brillouin scattering (SBS) threshold in single-mode optical fibers with different refractive index profiles. We confirm our results by several representative measurements. We show that with the proper profile design one can achieve more than 3 dB increase in the SBS threshold compared to the standard single-mode optical fiber.

502 Watt, single transverse mode, narrow linewidth, bidirectionally pumped Yb-doped fiber amplifier

High power operation of narrow linewidth optical fiber amplifiers is usually limited by the onset of stimulated Brillouin scattering. In this paper, we present results demonstrating over 500 Watts of power in a single mode beam from a fiber designed to suppress stimulated Brillouin scattering through a reduction in the overlap of the optical and acoustic fields. Simulations demonstrate the potential for this fiber to achieve greater than 1000 Watts of output power.

Brillouin gain analysis for fibers with different refractive indices

We studied an anomalous result in the measured stimulated Brillouin scattering threshold for single-mode optical fibers with different refractive index profiles and effective areas. It was found that, in addition to the optical effective area, the refractive-index-dependent interaction between the optical and the acoustic fields must be considered in order to account for the differences in the stimulated Brillouin scattering threshold between fiber types. A detailed analytical formalism describing the acousto-optic interaction was derived to accommodate the influence of the index profile design on Brillouin scattering.

Fiber designs for high power lasers

This paper reviews different fiber design approaches for high power lasers. First, we discuss the conventional step index profile design and methods for achieving single mode operation in high power lasers such as bending, helical core fibers and Yb dopant profile designs. Then we present new design approaches for reducing the SBS through profile and glass composition designs. Finally, we describe fiber designs to achieve single polarization and at the same time to mitigate the SRS effect.

Ultra-low-loss optical fiber enabling purely passive 10 Gb/s PON systems with 100 km length.

We demonstrate time division multiplexing (TDM) and wavelength division multiplexing/TDM (WDM/TDM) long reach 10 Gb/s passive optical network (PON) architectures of 100 km reach with no infield amplification or dispersion compensation. The purely passive nature of the 100 km systems is enabled by the use of ultra-low-loss optical fiber with average attenuation of 0.17 dB/km and downstream transmission with a 10 Gb/s signal modulated with the duobinary format. The high tolerance of duobinary to dispersion, stimulated Brillouin scattering (SBS), and self-phase modulation (SPM) are all key factors to achieving good system performance at this distance, as is the significantly reduced loss from the ultra-low-loss fiber. We show that this combination of fiber and downstream signal format allow split ratios up to 1:128 for both system architectures. The achievable split ratio is reduced for standard single-mode fiber and/or use of an NRZ modulated downstream signal. Standard strength forward error correction (FEC) is used for the WDM/TDM system but is not required for the TDM system.

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.

Enhanced stimulated Brillouin scattering threshold through phase control of multitone phase modulation

We show that controlling the phase difference among the various tones of a multitone phase modulator can substantially increase the stimulated Brillouin scattering (SBS) threshold during optical fiber transmission. We present detailed modeling and experimental validation of the effect. This result should be especially useful for optical networks requiring high signal launch power.

Supercontinuum generation in optical fibers

In this paper, we studied SC generation in fiber lasers and in optical fibers pumped by different light sources which include fs and ps pulse sources, and continuous-wave (CW) amplified spontaneous emission (ASE) light sources. First, we demonstrated SC generation with a 10dB spectral bandwidth of 430nm in a fiber ring laser with conventional nonlinear fiber. Second, we proposed and demonstrated a new and efficient approach to generation of a CW SC in optical fibers pumped by a CW ASE light. A bandwidth of 268nm (at -15dB level) with an average spectral density of 2.7mW/nm was demonstrated. Various approaches to flattening the spectrum and increasing the spectral width were also studied. The application of this SC source in WDM passive optical access networks (WDM-PONs) was investigated. Third, the approach of SC generation in a fiber combination of standard SMF and nonlinear DSF pumped by an all-fiber fs pulse Master Oscillator Power Amplifier (MOPA) system was developed. A spectral bandwidth of over 1000nm was demonstrated. Finally, the generation of broad comb-like-spectral light based on the pulse compression of 40GHz optical pulses in a new nonlinear dispersion-decreasing fiber with high SBS threshold was studied. A continuum light source with over 125 channels and a channel spacing of 40 GHz was achieved. The use of this continuum light source as WDM source in WDM-PONs was investigated.

Suppression of Stimulated Brillouin Scattering in High Power, Narrow Linewidth Fiber Amplifiers

Stimulated Brillouin scattering in optical fibers is suppressed by spatially separating the optical and acoustic modes. Using this technique, we demonstrate 500 Watts of output power from a single mode, narrow linewidth fiber amplifier.

Passive stimulated Brillouin scattering suppression for broadband passive optical networks

We demonstrate passive SBS suppression through fiber design enabling 4.0-dB advantage compared to standard single-mode fiber, while maintaining compliance with ITU G.652.D requirements. We further demonstrate this advantage by monitoring common analog video metrics.