We report on photodarkening (PD) investigations at Yb doped fibers with specific variation of
the concentrations of the codopants aluminum and phosphorus, measured during cladding …

The fiber laser, with its humble beginning in the late 1980s, has undergone tremendous
development in the past decade or so, transforming itself from a research curiosity to a major …

We show by numerical modeling that saturation of the population inversion reduces the
stimulated thermal Rayleigh gain relative to the laser gain in large mode area fiber …

We present theoretical study of wavelength dependence of mode instability (MI) in high
power fiber lasers, which employs an improved semi-analytical theoretical model. The …

We theoretically detail and explain how to control unwanted excess gain for higher order
modes in cladding-pumped large-core ytterbium-doped fiber amplifiers operating on the …

Due to the excellent infrared transparency, low phonon energy, and high rare‐earth
solubility, germanate laser glass has attracted much attention in mid‐infrared fiber lasers for …

In this paper we discuss recent progress in exploring short-term and long-term stability of
high power Yb-doped fiber lasers and amplifiers. Long-term stability is associated with …

Using a numerical model we study the frequency dependence of mode coupling gain due to
stimulated thermal Rayleigh scattering in step index, Yb doped, fiber amplifiers. The …

Novel transverse techniques for measuring the refractive index profile and spontaneous
emission of high-power optical fibers are described. These techniques are particularly …

Photodarkening is presently a major concern for the long term reliability and efficiency of
high power Yb-doped fiber lasers and amplifiers. This phenomenon has been associated …