A topical review of numerical and experimental studies of supercontinuum generation in photonic crystal fiber is presented over the full range of experimentally reported parameters, from the femtosecond to the continuous-wave regime. Results from numerical simulations are used to discuss the temporal and spectral characteristics of the supercontinuum, and to interpret the physics of the underlying spectral broadening processes. Particular attention is given to the case of supercontinuum generation seeded by femtosecond pulses in the anomalous group velocity dispersion regime of photonic crystal fiber, where the processes of soliton fission, stimulated Raman scattering, and dispersive wave generation are reviewed in detail. The corresponding intensity and phase stability properties of the supercontinuum spectra generated under different conditions are also discussed.

Supercontinuum generation in photonic crystal fiber

We present the science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems, targeting an evolution in technology, that might lead to impacts and benefits reaching into most areas of society. This roadmap was developed within the framework of the European Graphene Flagship and outlines the main targets and research areas as best understood at the start of this ambitious project. We provide an overview of the key aspects of graphene and related materials (GRMs), ranging from fundamental research challenges to a variety of applications in a large number of sectors, highlighting the steps necessary to take GRMs from a state of raw potential to a point where they might revolutionize multiple industries. We also define an extensive list of acronyms in an effort to standardize the nomenclature in this emerging field.

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Science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems

The neonatal Fc receptor for IgG (FcRn) has been well characterized in the transfer of passive humoral immunity from a mother to her fetus. In addition, throughout life, FcRn protects IgG from degradation, thereby explaining the long half-life of this class of antibody in the serum. In recent years, it has become clear that FcRn is expressed in various sites in adults, where its potential function is now beginning to emerge. In addition, recent studies have examined the interaction between FcRn and the Fc portion of IgG with the aim of either improving the serum half-life of therapeutic monoclonal antibodies or reducing the half-life of pathogenic antibodies. This Review summarizes these two areas of FcRn biology.

FcRn: the neonatal Fc receptor comes of age

The rise in output power from rare-earth-doped fiber sources over the past decade, via the use of cladding-pumped fiber architectures, has been dramatic, leading to a range of fiber-based devices with outstanding performance in terms of output power, beam quality, overall efficiency, and flexibility with regard to operating wavelength and radiation format. This success in the high-power arena is largely due to the fiber’s geometry, which provides considerable resilience to the effects of heat generation in the core, and facilitates efficient conversion from relatively low-brightness diode pump radiation to high-brightness laser output. In this paper we review the current state of the art in terms of continuous-wave and pulsed performance of ytterbium-doped fiber lasers, the current fiber gain medium of choice, and by far the most developed in terms of high-power performance. We then review the current status and challenges of extending the technology to other rare-earth dopants and associated wavelengths of operation. Throughout we identify the key factors currently limiting fiber laser performance in different operating regimes—in particular thermal management, optical nonlinearity, and damage. Finally, we speculate as to the likely developments in pump laser technology, fiber design and fabrication, architectural approaches, and functionality that lie ahead in the coming decade and the implications they have on fiber laser performance and industrial/scientific adoption.

High power fiber lasers: current status and future perspectives [Invited]

The present invention concerns polypeptides comprising a variant Fc region. More particularly, the present invention concerns Fc region-containing polypeptides that have altered effector function as a consequence of one or more amino acid modifications in the Fc region thereof.

Polypeptide variants with altered effector function

Summary form only given. Cladding pumped fiber amplifiers with high, in excess of 40 W, c.w. output powers are rapidly becoming attractive replacements for diode pumped solid state lasers. One particularly flexible and efficient configuration is that of the seeded or master oscillator-power fiber amplifier (MOPFA). Weak seed signals from diode or fiber lasers in all-fiber coupled formats allow enormous diversity in the output parameters of the source from narrow linewidth to ultrashort pulses at selectable repetition rates and at high average saturated powers over an expansive wavelength range. Parallel progress in the fabrication of periodically poled crystals' applied to quasi-phase matched non-linear processes has made a significant impact, allowing high conversion efficiencies to be obtained in association with low/medium power optical pump sources. To date, the majority of the pump sources employed have been diode pumped solid state lasers, although clearly not exclusively.

Efficient non-linear conversion in periodically-poled crystals using high power, seeded, fiber-amplifiers

SHG of single-frequency CW Yb/Er fiber source in PPKTP and PPLN is investigated. 30% conversion efficiency and 9 W output power at 780 nm are demonstrated in single pass configuration. Possible applications for laser cooling are discussed.

Multi-watt, 780 nm, single-frequency CW fiber-based by SHG in PPLN and PPKTP

Pumping highly-nonlinear PCF with zero-dispersion around the wavelength of a 70kW peak, 8W average power, ps Yb-fibre laser allowed realization of a picosecond, all-fibre, source in 525-1800nm region. Possibility of fibre-based femtosecond compression is demonstrated.

High Brightness, Visible to Infrared Picosecond Generation with All-Fibre Format Yb Laser

We report use of 15-60m long, dispersion-decreasing tapered solid-core photonic crystal fibers for adiabatic soliton compression at 1.06µm wavelength. 655fs input pulses were compressed to 43fs solitons.

Pulse Compression at 1.06μm in Dispersion Decreasing Photonic Crystal Fibers

R. I. Woodward,1 E. J. R. Kelleher,1 T. H. Runcorn,1 S. Loranger,2 D. Popa,3 V. J. Wittwer,3 A. C. Ferrari,3 S. V. Popov,1 R. Kashyap,2,4 and J. R. Taylor1 1. Femtosecond Optics Group, Department of Physics, Imperial College London, SW7 2AZ, UK 2. Fabulas Laboratory, Department of Engineering Physics, Polytechnique Montréal, H3T 1J4, Canada 3. Cambridge Graphene Centre, University of Cambridge, Cambridge, CB3 0FA, UK 4. Fabulas Laboratory, Department of Electrical Engineering, Polytechnique Montréal, H3T 1J4, Canada

Sergei Popov

Papers

Efficient non-linear conversion in periodically-poled crystals using high power, seeded, fiber-amplifiers

Multi-watt, 780 nm, single-frequency CW fiber-based by SHG in PPLN and PPKTP

High Brightness, Visible to Infrared Picosecond Generation with All-Fibre Format Yb Laser

Pulse Compression at 1.06μm in Dispersion Decreasing Photonic Crystal Fibers

Nanosecond to picosecond fiber bragg grating compression of giant-chirped pulses from an ultra-long mode-locked fiber laser