Using a beam propagation model of Yb3+ doped, CW fiber amplifiers we show that gain saturation by a strong fundamental mode significantly suppresses the growth of higher order modes with parallel polarization, but enhances the growth of higher order modes with perpendicular polarization. We quantify this effect in straight and bent fibers, with full core or restricted area doping.

We demonstrate a multistage erbium fiber amplifier seeded by a gain-switched laser diode operating at a wavelength of 1550 nm and a repetition rate of 1 MHz. The pulse energy is 0.5 μJ, and the pulse duration is 40 ps, resulting in a peak power of 11.4 kW. The three-stage all-fiber amplifier system is designed to avoid any spectral distortions induced by gain saturation or nonlinear effects and...

We investigated the carrier-envelope phase (CEP) stability of hollow-fiber compression for high-energy few-cycle pulse generation. Saturation of the output pulse energy is observed at 0.6 mJ for a 260 μm inner-diameter, 1 m long fiber, statically filled with neon. The pressure is adjusted to achieve output spectra supporting sub-4-fs pulses. The maximum output pulse energy can be increased to 0...

Amplification of ultrashort solitons in fiber amplifiers is discussed by considering a general model that includes gain saturation, gain dispersion, and intrapulse stimulated Raman scattering. The numerical results show that an interplay between gain dispersion and intrapulse Raman scattering can lead to novel temporal and spectral features. Under high-gain conditions the input pulse is found t...

Let F = (E, p, B;Y ) be a fiber bundle where E, B and Y are connected finite polyhedra. Let f : E → E be a fiber-preserving map and A ⊆ E a closed, locally contractible subset. We present necessary and sufficient conditions for A and its subsets to be the fixed point sets of maps fiber-homotopic to f . The necessary conditions correspond to those introduced by Schirmer in 1990 but, in the fiber...

In this work, we propose a new statistical randomness test, the Saturation Point Test, which can be applied to integer sequences as well as binary sequences and is designed to increase the number of tests for short sequences. The subject of Saturation Point Test is the index of integer, denoted by SP , where all possible integers occur in the given sequence. We evaluate the probability Pr(SP = ...

The aim of this study was to synthesis of glass ionomer-silk fiber composite and to evaluate the effect of adding natural degummed silk fiber on the mechanical properties of glass ionomer cement (GIC). For this purpose, natural degummed silk fibers with 1 mm in length and 13-16 µm in diameter were added to the ceramic component of a commercial glass ionomer cement in 1, 3 and 5 wt. %. Compressi...