Preparation and characterization of highly thulium- and alumina-doped optical fibers for single-frequency fiber lasers

Thulium-doped fibers suitable for core-pumped single-frequency lasers were fabricated by the modified chemical vapor deposition (MCVD) method. Refractive index profile, doping profile and spectral absorption was measured. High doping concentration of thulium ions should be achieved to allow for high absorption of light at a pump wavelength while the thulium ions clustering should be avoided to prevent the cooperative upconversion and quenching processes. The fabricated fibers featured pump absorption up to 70dB/m at a pump wavelength of 1611nm. The single-frequency master oscillator with a resonator composed of a pair of fiber Bragg gratings and a thulium-doped fiber was demonstrated with predominantly single ended operation. We achieved a slope efficiency of 22% and a threshold of 22mW at a lasing wavelength of 1944nm

Self-induced laser line sweeping in double-clad Yb-doped fiber-ring lasers

International audienceExperimental observation of the self-induced laser line sweeping (SLLS) in fiber ring lasers is presented. The SLLS with the same gain fiber is studied in Fabry-Perot cavity for comparison. The SLLS effect manifests itself as a laser wavelength drift with speed of the order of nanometer per second from shorter to longer wavelengths across several nanometers and fast backward jump. Recently, the dynamics of the SLLS in a Fabry-Perot cavity fiber laser was qualitatively described by a dynamic grating induced by spatial-hole-burning in the ytterbium doped fiber where the lifetime of the grating was related to the self-sustained relaxation oscillations. In this paper we address possible discrepancies between the published theoretical model and earlier observations of SLLS, particularly in fiber-ring lasers.We show that the qualitative theoretical model developed for explaining SLLS in the Fabry-Perot cavity can be used also to explain the SLLS effect we observed earlier in fiber-ring lasers

Kubicko-kvinticke nelinearni jevy v optickych vlaknech

Some classical and quantum phenomena of third and fifth order are studied in the work. Quantum state of light at output ports of a beam splitter when both its input ports are in a Kerr and quintic state is found in the first part. Statistical properties of this combined state are studied and photocount distribution of non-ideal photodetectors and the output signal of homodyne receiver are calculated. Interaction of two quasi-solitons in optical fibres with cubic-quintic nonlinearity is investigated in the second part using the pertubation approach. The results are compared to numerical simulations. Quasi-solitons collapse distance is discussed for three different cases of interaction between quasi-solitons from lower and upper branch. Soliton fusion is observed both for the upper and the lower quasi-soliton branches. Two photon absorption and linear absorption influence on quasi-soliton fusion is investigatedAvailable from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi