P. Dupriez

Single-frequency, single-mode, plane-polarized ytterbium-doped fiber master oscillator power amplifier source with 264 W of output power

We present a single-frequency, single-mode, plane-polarized ytterbium-doped all-fiber master oscillator power amplifier source at 1060 nm generating 264 W of continuous-wave output power. The final-stage amplifier operated with a high gain of 19 dB and a high conversion efficiency of 68%. There was no evidence of rollover from stimulated Brillouin scattering even at the highest output power, and the maximum output was limited only by the available pump power.

High average power, high repetition rate, picosecond pulsed fiber master oscillator power amplifier source seeded by a gain-switched laser diode at 1060 nm

We demonstrate a pulsed ytterbium-doped fiber master-oscillator power amplifier source at 1060 nm producing over 300 W of average power in 20-ps pulses at 1-GHz repetition rate. The pulses generated by a gain-switched diode were compressed by a chirped fiber Bragg grating and amplified without any distortion with excellent spectral quality. This fiber master oscillator power amplifier system offers versatility and potential for further power scaling.

High-power, high repetition rate picosecond and femtosecond sources based on Yb-doped fiber amplification of VECSELs

Picosecond pulses at gigahertz repetition rates from two different passively mode-locked VECSELs are amplified to high powers in cascaded ytterbium doped fiber amplifiers. Small differences in pulse durations between the two VECSELs led to amplification in different nonlinear regimes. The shorter 0.5 ps pulses could be amplified to 53 W of average power in the parabolic pulse regime. This was confirmed by excellent pulse compression down to 110 fs. The VECSEL producing longer 4.6 ps pulses was amplified in an SPM dominated regime up to 200 W of average power but with poor recompressed pulse quality.

Suppression of stimulated Raman scattering in a high power Yb-doped fiber amplifier using a W-type core with fundamental mode cut-off

We demonstrate the suppression of stimulated Raman scattering in a high power, single-mode Yb-doped fiber amplifier using a W-type core structure. Raman-scattered light is not guided by the core. The amplifier consists of a master oscillator power amplifier (MOPA) system, seeded with 103 ps pulses at 32 MHz repetition rate in the final amplification stage. An average output power of 53 W, which corresponds to 13 kW of peak power, was achieved in the 23 m long W-type double-clad fiber without any significant loss of power due to transfer from the signal wavelength at 1060 nm to the Raman Stokes wavelength at 1114 nm and amplified spontaneous emission from Yb-ions at longer wavelengths (~1070 nm). The power conversion efficiency at 1060 nm was 80% with respect to the absorbed pump power.

High-power continuous-wave cladding-pumped Raman fiber laser

We demonstrate a high-power single-mode cladding-pumped Raman fiber laser. The Raman fiber laser consists of a 1.2 km long germanium-doped double-clad fiber in a linear cavity, which is spliced to a single-mode fiber. The laser is end pumped by a multimode erbium-ytterbium-doped fiber, which is coupled to the inner cladding of the Raman fiber. The embedded core was designed to be single mode at the Raman Stokes wavelength, and up to 10 W of power was obtained at 1660 nm from the single-mode fiber end. The laser has a slope efficiency of 67% and a threshold of 6.5 W.

Neodymium-doped cladding-pumped aluminosilicate fiber laser tunable in the 0.9-/spl mu/m wavelength range

A tunable high-power cladding-pumped neodymium-doped aluminosilicate fiber laser is demonstrated. The maximum power reached was 2.4 W with a slope efficiency of 41% and a threshold pump power of 1.68 W, both with respect to launched pump power, when cladding pumped by two 808-nm diode pump sources at both fiber ends. The dependence of the tuning range on the fiber length is investigated. The tuning range changed from 922 to 942 nm for a 25-m-long fiber to 908-938 nm with a 14-m-long fiber, because of reabsorption effects. The output linewidth was 0.26 nm in a diffraction-limited beam. Operation on the challenging 0.9-/spl mu/m three-level transition in neodymium-doped double-clad fiber laser was facilitated by a W-type core refractive index profile. This filtered out the unwanted and competing strong transition at 1.06 /spl mu/m while guidance of 0.9 /spl mu/m remained intact.

High power tunable femtosecond soliton source using hollow-core photonic bandgap fiber, and its use for frequency doubling

We report a high power tunable femtosecond soliton-based source using a simple combination of fiber-amplified pulses at 1064 nm and hollow-core photonic bandgap fiber. Compression of 5.5 ps input pulses, strongly chirped by self phase modulation in the amplifier, results in stable 520 fs-soliton formation with 77% conversion efficiency after only 8m propagation in the hollow-core fiber. The Raman self-frequency shift of the solitons was used to provide 33 nm wavelength tuneability. The transform-limited output pulses were frequency doubled using a nonlinear crystal with high conversion efficiency of 60% to demonstrate a femtosecond green laser tunable from 534 nm to 548 nm with 180 nJ pulse energy.

Advances in high power short pulse fiber laser systems and technology

We review recent advances in Yb fiber lasers and amplifiers for high power short pulse systems. We go on to describe associated recent developments in fiber components for use in such systems. Examples include microstructured optical fibers for pulse compression and supercontinuum generation, and advanced fiber grating technology for chirped-pulse amplifier systems.

321 W average power, 1 GHz, 20 ps, 1060 nm pulsed fiber MOPA source

Pulses from a gain-switched laser diode were amplified in a fiber MOPA system to produce in excess of 320 W of average power in 20 ps pulses at 1 GHz repetition rate at 1060 nm.

High power red and near-IR generation using four wave mixing in all integrated fibre laser systems

We demonstrate high power generation of visible red and near IR light by four wave mixing in photonic crystal fibres (PCFs) pumped at 1064 nm with picosecond pulses (30 - 80 ps). 30% conversion efficiency is demonstrated in a single pass using fibre lengths less than 1 m, with signal wavelengths from 650 nm to 820 nm selectable by choice of PCF. An all fibre integrated system delivers 2.16 W at 740 nm with a pulse repetition frequency of 20 MHz. We discuss the overall parameter space for this type of wavelength conversion in PCF with different fibre designs suitable for delivering a particular wavelength at low or high power.