A.S. Kurkov

Modeling of CW Yb-doped fiber lasers with highly nonlinear cavity dynamics

We develop a theoretical framework for modeling of continuous wave Yb-doped fiber lasers with highly nonlinear cavity dynamics. The developed approach has shown good agreement between theoretical predictions and experimental results for particular scheme of Yb-doped laser with large spectral broadening during single round trip. The model is capable to accurately describe main features of the experimentally measured laser outputs such as power efficiency slope, power leakage through fibre Bragg gratings, spectral broadening and spectral shape of generated radiation.

All-fiber 10 W holmium lasers pumped at λ=1.15 μm

Three all-fiber Ho-doped lasers emitting in the range of 2050-2100 nm were fabricated. The lasers were pumped by an Yb-doped fiber laser at 1147 nm with a power up to 35 W. For all the lasers tested, the output power was found to be as high as 10 W, the efficiency slope being 30%.

Raman fiber laser for the drug-free photodynamic therapy

An SRS laser with a radiation wavelength of 1.262 μm and a maximum power of 5.5 W is presented. The laser wavelength corresponds to the excitation band of singlet oxygen and can be used for the treatment of oncological diseases. The laser source is employed for the treatment of basalioma.

Femtosecond mode-locked holmium fiber laser pumped by semiconductor disk laser

We report on a 2085 nm holmium-doped silica fiber laser passively mode-locked by semiconductor saturable absorber mirror and carbon nanotube absorber. The laser, pumped by a 1.16 μm semiconductor disk laser, produces 890 femtosecond pulses with the average power of 46 mW and the repetition rate of 15.7 MHz.

Experimental and numerical optimization of a fiber Raman laser

We present an experimental test of a recently published model that describes a nested fiber Raman cavity taking into account all interactions between forward and backward traveling waves. The experiment consists in the realization of a one-stage fiber Raman laser, pumped at 1090 nm, using one Stokes shift to produce output radiation at 1150 nm. The conversion efficiency measured as a function of input power and fiber length is successfully compared with the numerical results. We also apply the model to the comparison between the performance of phosphosilicate (PS) and germanosilicate (GS) fibers. We have considered a five-step Raman laser using a GS fiber with a 1117 nm pump, and a two-step Raman laser using a PS fiber with a 1061 nm pump, both emitting at 1480 nm. In the optimum configuration, the simpler PS fiber laser presents a conversion efficiency about 15% lower than that of the GS fiber laser and uses a fiber length 40% larger.

Waveguide-saturable absorber fabricated by femtosecond pulses in YAG:Cr4+ crystal for Q-switched operation of Yb-fiber laser

A waveguide-saturable absorber with low propagation loss is fabricated by femtosecond pulses in YAG:Cr(4+) crystal. Q-switch operation of a Yb fiber laser with the new saturable absorber having absorption saturation parameters similar to the bulk YAG:Cr(4+) crystal is demonstrated.

Yb3+-doped double-clad fibers and lasers

We present results of the research and development of double-clad Yb3+-doped fibers for high-power fiber lasers. The quality of the fabricated fibers and optimization of reflecting Bragg gratings allowed us to demonstrate fiber lasers with a quantum efficiency close to 90%. These fiber lasers were used in Raman converters emitting at various wavelengths.

Application of reduced-pressure plasma CVD technology to the fabrication of Er-doped optical fibers

Abstract For the first time the reduced-pressure plasma CVD technology was applied to fabrication of active silica optical fibers with all-depressed index structure. Using surface plasma CVD method, fiber preforms with an Er-doped silica core and fluorine doped silica cladding have been prepared and tested. A possibility of high performance active fiber fabrication using the SPCVD has been demonstrated. An influence of fluorine co-doping on luminescence features of Er 3+ ions in a silica host has been examined. The erbium concentration-associated clustering effects in pure silica host synthesized by the SPCVD were compared with those in germanosilicate host synthesized by the MCVD.

A 160 W single-frequency laser based on an active tapered double-clad fiber amplifier

We present a CW single-frequency laser at 1062 nm (linewidth <3?MHz) with 160?W of total output power based on a two stage fiber amplifier. A GTWave fiber is used for the first stage of the amplifier. A tapered double-clad fiber (T-DCF) is used for the second stage of the amplifier. The high output power is achieved due to the amplified spontaneous emission (ASE) filtering and increased stimulated Brillouin scattering (SBS) threshold inherent to the axially non-uniform geometry.

Composite laser fiber with Yb, Er co-doped phosphate glass core and silica cladding

This letter is devoted to fabrication and tests of an optical fiber with a phosphate glass core in a silica cladding. The fiber preform was made by melting Yb, Er co-doped phosphate laser glass in a high-purity silica tube. 1.54 μm laser action was demonstrated under 1.06 μm pumping into the Yb absorption band.