Pulsed Fibre Lasers

This group is part of the Advanced Fibre Technologies & Applications Group

Fibre laser technology offers tremendous prospects for the development of compact, robust pulse sources capable of operating over a very wide range of pulse parameters spanning from the microsecond down to the femtosecond regime. The ORC has been engaged in pulsed fibre laser development since the first demonstration of fibre lasers in the mid-1980s. Over this period it has produced numerous world first results most notably in the area of high energy Q-switched systems, passively mode-locked lasers, high average power pulsed systems and fibre laser pumped parametric devices.

By virtue of their excellent power handling characteristics and advances in both pump diode and fibre fabrication technology fibre lasers can now be made to reliably operate at kW average power levels, and are able to generate multi-mJ pulse energies. Consequently, fibre systems are now sufficiently powerful to be used in applications such as high-precision welding, cutting, and marking of metals and ceramics. Significantly, a number of car manufacturers now use laser welding to assemble vehicle bodies exploiting the high average powers that can be generated and accurately delivered to the workpiece.

For processes in which peak power is critical the possibility for high average powers can be exploited to obtain high pulse repetition rates and thus greatly increased processing speeds. A key feature of fibre lasers is that the laser beams generated are of a much higher beam quality than competing technologies and so can be focused to a much smaller spot size, or used to provide substantial increases in working distance from the target. This opens up a host of new material processing possibilities, such as precision manufacturing of tiny precision components for body implants, and the direct writing of optical and electrical circuits.

In general terms our current research is focused on:

• the development of ever more powerful pulsed lasers and amplifiers, both in terms of pulse peak power (>1GW) and average power (>300W)
• tailoring of the pulse characteristics to suit the growing range of pulsed fibre laser applications e.g. laser marking, welding and cutting
• nonlinearity and dispersion management in pulsed fibre laser systems
• frequency conversion of pulsed fibre laser output to new wavelength ranges using external nonlinear elements (e.g. to the X-ray, UV and mid-IR)
• the development of ever more reliable, practical and low cost systems

Active project areas include amongst others:

• Passively mode-locked fibre lasers
• Gain switched diode sources
• Fibre based Chirped Pulse Amplification
• Parabolic pulse generation
• Supercontinuum generation
• Nonlinearity control in short pulse amplifier systems
• Adaptive pulse shaping technology
• Pulsed lasers for industrial applications
• Q-switched fibre lasers
• Fibre pumped OPOs, OPAs and harmonic generators
• Numerical modelling of laser and amplifier systems
• Pulsed laser beam delivery

Much of our work is performed in close collaboration with other ORC groups, in particular the high power fibre laser, fibre grating and fibre fabrication groups, and with other external academic and industrial partners. Current collaborating organisations include amongst others: ETH Zurich, University of Dijon, Cambridge University, Lawrence Livermore National Laboratories, SPI Lasers Ltd, Sharp, BAe Systems and SELEX.

F.He, J.H.V.Price, K.T.Vu, A.Malinowski, J.K.Sahu, D.J.Richardson, Optimisation of cascaded Yb fiber amplifier chains using numerical-modelling, Optics Express 2006 Vol.14(26) pp.12846

M.L.V.Tse, P.Horak, J.H.V.Price, F.Poletti, F.He, D.J.Richardson, Pulse compression at 1.06 microns in dispersion-decreasing holey fibers, Optics Letters 2006 Vol.31(23) pp.3504-3506

A.Malinowski, A.Piper, J.H.V.Price, K.Furusawa, Y.Jeong, J.Nilsson, D.J.Richardson, Ultrashort-pulse Yb3+-fiber-based laser and amplifier system producing >25-W average power, Optics Letters 2004 Vol.29(17) pp.2073-5

J.H.V.Price, T.M.Monro, H.Ebendorff-Heidepriem, F.Poletti, V.Finazzi, J.Y.Y.Leong, P.Petropoulos, J.C.Flanagan, G.Brambilla, X.Feng, D.J.Richardson, Mid-IR supercontinuum generation in non-silica glass fibers, Photonics West San Jose, California 21-26 Jan 2006 (Invited)

K.T.Vu, A.Malinowski, D.J.Richardson, F.Ghiringhelli, L.M.B.Hickey, M.N.Zervas, Adaptive pulse shape control in a diode-seeded nanosecond fiber MOPA system, Optics Express 2006 Vol.14(2310996-11001)

P.Dupriez, C.Finot, A.Malinowski, J.K.Sahu, J.Nilsson, D.J.Richardson, K.G.Wilcox, H.D.Foreman, A.C.Tropper, High-power high repetition rate picosecond and femtosecond sources based on Yb-doped fiber amplification of VECSELs, Optics Express 2006 Vol.14(21) pp.9611-9616

P.Dupriez, A.Piper, A.Malinowski, J.K.Sahu, M.Ibsen, B.C.Thomsen, Y.Jeong, L.M.B.Hickey, M.N.Zervas, J.Nilsson, D.J.Richardson, High average power high repetition rate picosecond pulsed fiber master oscillator power amplifier source seeded by a gain-switched laser diode at 1060nm, IEEE Photonics Technology Letters 2006 Vol.18(9) pp.1013-1014

C.Finot, F.Parmigiani, P.Petropoulos, D.J.Richardson, Parabolic pulse evolution in normally dispersive fiber amplifiers preceding the similariton formation regime, Optics Express 2006 Vol.14 pp.3161-3170

A.Piper, A.Malinowski, K.Furusawa, D.J.Richardson, High-power high-brightness mJ Q-switched ytterbium-doped fibre laser, Electronics Letters 2004 Vol.40(15) pp.928-9

Recent world class results we have reported include:

• >300W average power obtained from an amplified gain switched system
• >150W fibre based femtosecond CPA system
• >50W 1 GHz, 100fs fibre system based on an optically pumped VCSEL seed laser