Jeffrey A. Demeritt

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.

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.

Optical Fibers With Tailored Acoustic Speed Profiles for Suppressing Stimulated Brillouin Scattering in High-Power, Single-Frequency Sources

In this paper, we discuss the design of optical fibers with tailored acoustic speed profiles to suppress stimulated Brillouin scattering in high-power, single-frequency sources. We demonstrate the ability of these fibers to achieve single-mode output powers of greater than 500 W and discuss the potential to achieve powers beyond 1 kW.

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.

Novel optical fiber design for low-cost optical interconnects in consumer applications

We propose a novel fiber design optimized for short-reach interconnects in consumer applications. A detailed analysis of the optical and mechanical properties of this fiber design is presented. Results are presented demonstrating (i) low bend loss and enhanced mechanical reliability in bends as small as 3 mm diameter; (ii) high power budget margin to enable relaxed mechanical tolerances on transmitter, receiver, and expanded-beam connectors for low-cost connectivity; and (iii) high bandwidth capability and system testing results at 10 Gb/s.

High power, narrow linewidth fiber lasers

Single transverse mode fiber lasers have recently achieved output powers at the kilowatt level. These breakthroughs can be attributed to the maturation of high power diode pump technology at 980 nm and the use of large mode area (LMA) fibers. In the continous wave (cw) operation regime, LMA fibers, through their reduction of device length and increase of the effective area, have been effective in the reduction of deleterious nonlinear optical effects such as stimulated Raman scattering (SRS). The use of LMA fiber has been less effective in the suppression of stimulated Brillouin scattering (SBS), for which the threshold can be several orders of magnitude lower than for SRS. In this work we use refractive index profiles and index modifying dopant distributions for the mitigation of SBS. Our theoretical and modeling efforts led to an experimentally demonstrated increase in SBS threshold of 2.5 dB for single mode fiber and 6 dB for LMA amplifier fiber. We discuss the use of this SBS-suppressive fiber in the demonstration of a high-power, narrow linewidth fiber amplifier.

High performance Yb-doped double-clad optical fibers for high-power, narrow-linewidth fiber laser applications

This paper outlines recent work at Corning Incorporated on fiber composition design and fabrication of a SBS-managed, large-mode-area (LMA), Yb-doped double-clad fiber for high-power, narrow-linewidth fiber laser applications. Through a detailed theoretical analysis for the SBS threshold in optical fibers, an Aluminum/Germanium (Al/Ge) counter-graded fiber-core composition profile has been proposed and demonstrated for reducing the SBS effect, via the reduced-overlap between optical and acoustic modes in the fiber design. Such Al/Ge counter-graded-composition-profile design overcomes the limitation in a multilayer fiber-core approach, in terms of the low-loss fiber fabrication. The new compositionally SBS-managed, LMA Yb-doped double-clad laser fiber fabricated through the new design, has shown more than ~7 dB improvement in SBS threshold over the conventional LMA fiber design. The new fiber offers exceptionally low passive-loss characteristics, and has been demonstrated with uncompromised high laser efficiency for high-power, narrow-linewidth fiber laser applications.

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.