D.Yu. Stepanov

Properties of Brillouin/erbium fiber lasers

The unique combination of two gain media in Brillouin/erbium fiber lasers results in distinctive properties of such sources. The paper describes in detail the output and efficiency properties of Brillouin/erbium fiber lasers, from experimental results and a theoretical model. Single longitudinal mode output with linewidth <10 kHz was measured, with a 4-nm tuning range with the Brillouin pump wavelength. Frequency pulling associated with the Brillouin gain was investigated and observed to increase linearly with the Brillouin pump power.

Multiple wavelength operation of distributed feedback fiber lasers

Summary form only given. Multiple wavelength distributed feedback (DFB) fiber lasers are attractive for a range of applications in optical communications, including soliton and microwave generation. Although such lasers have been demonstrated experimentally, it is not obvious how several laser modes can coexist in a homogeneously broadened gain medium. We propose that the coexistence of two or more fundamental modes of the same polarization can be attributed to the effect of dynamic gain gratings set up by the standing waves of different laser modes. A gain grating is in anti-phase with the standing wave pattern that created it, and therefore its presence is destructive for the corresponding laser mode. On the other hand, its interaction with other laser modes is small because of the frequency mismatch. Thus, the effect of the gain gratings is a reduction of the power of the dominant mode and an increase of the available gain for the other modes, resulting in a stable multiple wavelength operation of the laser.

Suppression of self-pulsations in DFB fiber lasers

Summary form only given. The origin of self-pulsations in Er-doped distributed-feedback (DFB) fiber lasers is related to ion clustering at high erbium concentrations. The clusters act as saturable absorbers with switching time much shorter than the population inversion recovery time and can eventually result in spiking behavior of the laser. Reducing the erbium concentration while still providing enough gain in a short cavity DFB fiber laser can be achieved by Yb co-doping which increases the pumping efficiency. Stabilization of the laser against self-pulsations can also be accomplished by resonant pumping or co-pumping directly into the metastable Er-ion state, damping down the oscillations of the population inversion.

High-resolution measurements of fibre Bragg grating transmission spectra

A high-resolution measurement technique for characterisation of fibre Bragg grating transmission spectra is demonstrated. Real-time measurements of a grating passband with 100 kHz spectral resolution are reported.