A. B. Rulkov

Visible supercontinuum generation in photonic crystal fibers with a 400W continuous wave fiber laser

We demonstrate continuous wave supercontinuum generation extending to the visible spectral region by pumping photonic crystal fibers at 1.07 microm with a 400 W single mode, continuous wave, ytterbium fiber laser. The continuum spans over 1300 nm with average powers up to 50 W and spectral power densities over 50 mW/nm. Numerical modeling and understanding of the physical mechanisms has led us to identify the dominant contribution to the short wavelength extension to be trapping and scattering of dispersive waves by high energy solitons.

Watts-level frequency doubling of a narrow line linearly polarized Raman fiber laser to 589 nm

A single-mode, linearly polarized, 1118 nm ytterbium fiber laser was applied to pumping of a short fiber length, polarization-maintaining Raman cavity, resulting in a 0.4 nm linewidth, 23 W CW source at 1179 nm. Efficient, single-pass frequency doubling of the Raman source in MgO doped PPLN to 589 nm was demonstrated with CW power levels in excess of 3 W. No beam quality degradation was observed due to photorefraction at pump power densities up to 2 MW/cm(2). The proposed approach can be readily extended to Watt-level generation of any desired wavelength in the 560 to 770 nm range.

Narrow-line, 1178nm CW bismuth-doped fiber laser with 6.4W output for direct frequency doubling

We achieved a 0.2nm linewidth output at 1178nm with powers up to 6.4W in a linear 80m Bismuth-doped fiber cavity pumped by a 55W Yb fibre laser. The potential of frequency doubling of the non-polarized output at 1178nm in MgO doped periodically poled lithium niobate was demonstrated and resulted in 125mW average power at 589nm. The approach can be extended to a linearly-polarized large mode area format with under 0.1nm linewidth capable of scaling to Watts level in the 560-620nm range.

Optical pulse compression in dispersion decreasing photonic crystal fiber.

Improvements to tapered photonic crystal fiber (PCF) fabrication have allowed us to make up to 50 m long PCF tapers with loss as low as 30 dB/km. We discuss the design constraints for tapered PCFs used for adiabatic soliton compression and demonstrate over 15 times compression of pulses from over 830 fs to 55 fs duration at a wavelength of 1.06 lm, an order of magnitude improvement over previous results.

High brightness picosecond all-fiber generation in 525–1800nm range with picosecond Yb pumping

Pumping of highly-nonlinear microstructured fibers with zero-dispersion around the pump wavelength of a 50kW peak-power picosecond Yb-fiber laser allowed extensive polychromatic picosecond operation down to 525nm in all-fibre format. Spectral power densities over 1mW/nm and potential of further pulse compression to femtoseconds is demonstrated.

High-peak-power femtosecond pulse compression with polarization-maintaining ytterbium-doped fiber amplification

We report the generation of 140 fs pulses with a peak power of up to 270 kW using a fiber pulse source based on a polarization-maintaining ytterbium-doped fiber amplifier and a semiconductor saturable absorber mirror mode-locked fiber laser seed. The seed laser pulses were amplified and chirped in the fiber amplifier and subsequently compressed in an external transmission grating pair. The use of a polarization-maintaining amplifier addresses nonlinear polarization-induced limitations to the obtainable compressed pulse duration and quality that can arise if isotropic fiber amplification is used. Numerical simulations of the system support the experimental measurements and also confirm the role of fiber dispersion in obtaining high-quality compressed pulses.

Multi-watt supercontinuum generation from 0.3 to 2.4 μm in PCF tapers

Supercontinua spanning 320-2400nm have been generated in long photonic-crystal-fiber tapers. Total average powers of over 3.5W and spectral-power-densities in the blue of over 5mW/nm are demonstrated. Use as a broadly-tunable pulse source is proposed.

High brightness polychromatic visible generation in photonic crystal fibers with picosecond Yb pumping

Pumping of highly-nonlinear microstructured fibers with zero-dispersion around the pump wavelength with kW peak-power picosecond Yb-fiber laser allowed polychromatic picosecond operation down to 525 nm. Methods of extension of operation further to the blue are proposed.

High-power completely fiber integrated super-continuum sources (Invited Paper)

Advances in high power fibre lasers and amplifiers and in novel non-linear fibres that can be readily integrated with such pumps have led to a family of high power super-continuum sources that extend throughout the complete window of transparency of silica based fibres. The systems have been operated femtosecond, picosecond and nanosecond as well as cw. Average powers of 10’s Watts can be easily achieved, giving flat spectral power densities in excess of 10’s mW per nm from 400 nm to beyond 2.2 μm.

Pulse Compression in Dispersion Decreasing Photonic Crystal Fiber

We report dispersion decreasing photonic-crystal-fibers for soliton compression at 1.06 mum. Fibers 15-60 m long with dispersion varying from 40-0 ps.nm-1.km-1 were used to achieve compression ratios of over 15. Pulses of 655 fs were compressed to 43 fs solitons.