Diode-pumped narrow linewidth multi-kilowatt metalized Yb fiber amplifier.

We investigate high brightness pumping of a multi-kilowatt Yb fiber amplifier in a bi-directional pumping configuration. Each pump outputs 2 kW in a 200 μm, 0.2 NA multimode fiber.

Seven-core erbium-doped double-clad fiber amplifier pumped simultaneously by side-coupled multimode fiber.

We demonstrate a seven-core erbium-doped fiber amplifier in which all the cores were pumped simultaneously by a side-coupled tapered multimode fiber. The amplifier has multicore (MC) MC inputs and MC outputs, which can be readily spliced to MC transmission fiber for amplifying space division multiplexed signals. Gain over 25 dB was obtained in each of the cores over a 40-nm bandwidth covering the C-band.

Multicore, tapered optical fiber for nonlinear pulse reshaping and saturable absorption.

We present a new method to create a coupled waveguide array via tapering a seven-core telecommunications fiber. The fiber based waveguide array is demonstrated to exhibit the novel physics associated with coupled waveguide arrays, such as discrete diffraction and discrete self-focusing. The saturable absorber characteristics of the device are characterized and an autocorrelation measurement reveals significant single-pass pulse reshaping.

Crosstalk in multicore fibers with randomness: gradual drift vs. short-length variations.

Random perturbations play an important role in the crosstalk of multicore fibers, and can be captured by statistical coupled-mode calculations. In this approach, phase matching contributes a multiplicative factor to the average crosstalk, depending on the perturbation statistics and any intentional heterogeneity of neighboring cores. The impact of perturbations is shown to be qualitatively different depending on whether they are gradually varying, or have short-length (centimeter-scale) variations.

Statistics of crosstalk in bent multicore fibers.

A statistical theory for crosstalk in multicore fibers is derived from coupled-mode equations including bend-induced perturbations. Bends are shown to play a crucial role in crosstalk, explaining large disagreement between experiments and previous calculations. The average crosstalk of a fiber segment is related to the statistics of the bend radius and orientation, including spinning along the fiber length.

Optical limiting properties of nonlinear multimode waveguide arrays.

An experimental investigation of the transmission of multimode capillary waveguide arrays containing a liquid nonlinear absorber shows an enhanced nonlinear response relative to that found in a single waveguide and to the same length of bulk material. Comparison of the nonlinear response of arrays with different pitch to diameter (d/Lambda) ratios confirm that both the intensity distribution within an individual waveguide and coupling between the elements of the array influence the overall nonlinear response.

Wavelength-selective core-to-jacket coupling in optical fiber.

Mode coupling between the fundamental core mode of an as-drawn optical fiber operating far from cutoff and higher-order modes in the plastic jacketing has been observed. In one fiber, the transmission spectrum of the core exhibited five distinct minima between 1200 and 1900 nm. By approximating the fiber jacket as an asymmetric slab waveguide of infinite lateral extent, the wavelengths of these transmission features were successfully predicted using coupled-mode theory.

Pulse compression using a tapered microstructure optical fiber.

We calculate the pulse compression in a tapered microstructure optical fiber with four layers of holes. We show that the primary limitation on pulse compression is the loss due to mode leakage. As a fiber's diameter decreases due to the tapering, so does the air-hole diameter, and at a sufficiently small diameter the guided mode loss becomes unacceptably high.