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81 results on '"Alkeskjold, Thomas T."'

55. Hybrid Photonic Crystal Fiber Components and Amplifiers

Author

Alkeskjold, Thomas T., primary, Laurila, Marko, additional, Hansen, Kristian R., additional, Jørgensen, Mette, additional, Petersen, Sidsel, additional, Lægsgaard, Jesper, additional, Olausson, Christina B., additional, and broeng, Jes, additional

Published
2012
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75. Ytterbium-doped large-mode-area photonic crystal fiber amplifier with gain shaping for use at long wavelengths

Author

Petersen, Sidsel R., Alkeskjold, Thomas T., Poli, Federica, Coscelli, Enrico, Jørgensen, Mette M., Laurila, Marko, Lægsgaard, Jesper, and Broeng, Jes

Abstract

A large-mode-area Ytterbium-doped photonic crystal fiber amplifier with efficient suppression of amplified spontaneous emission is presented. The fiber cladding consists of a hexagonal lattice of air holes, where three rows are replaced with circular high-index inclusions. Seven missing air holes define the large-mode-area core. Light confinement is achieved by combined index and bandgap guiding, which allows for single-mode operation and distributed spectral filtering of amplified spontaneous. The fiber properties give control of the gain shape and are ideal for amplification in the long wavelength regime of the Ytterbium gain spectrum above 1100 nm.

Published
2012
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79. Airclad fiber laser technology.

Author

Hansen, Kim P., Broeng, Jes, Maack, Martin D., Alkeskjold, Thomas T., Nikolajsen, Thomas, Skovgaard, Peter M. W., Sørensen, Mads H., Denninger, Mark, Jakobsen, Christian, Simonsen, Harald R., Olausson, Christina B., Noordegraaf, Danny, and Laurila, Marko

Subjects
FIBER lasers, LIGHT amplifiers, HIGH power lasers, OPTICAL fibers, FIBER optics, POLARIZATION (Electricity)
Abstract

High-power fiber lasers and amplifiers have gained tremendous momentum in the last 5 years. Many of the traditional manufacturers of gas and solid-state lasers are now pursuing the fiber-based systems, which are displacing the conventional technology in many areas. High-power fiber laser systems require reliable fibers with large cores, stable mode quality, and good power handling capabilities-requirements that are all met by the airclad fiber technology. In the present paper we go through many of the building blocks needed to build high-power systems and we show an example of a complete airclad laser system. We present the latest advancements within airclad fiber technology including a new 100 μm single-mode polarization-maintaining rod-type fiber capable of amplifying to megawatt power levels. Furthermore, we describe the novel airclad-based pump combiners and their use in a completely monolithic 350 W cw fiber laser system with an M2 of less than 1.1. [ABSTRACT FROM AUTHOR]

Published
2011
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80. Avoided-crossing based modal cut-off analysis of 19-cell double-cladding photonic crystal fibers

Author

Poli, Federica, Coscelli, Enrico, Alkeskjold, Thomas T., Sozzi, Michele, Cucinotta, Annamaria, Selleri, Stefano, Leick, Lasse, and Broeng, Jes

Abstract

The modal cut-off properties of Yb-doped Double-Cladding Photonic Crystal Fibers (DC-PCFs) with 19-cell core have been analyzed considering an innovative approach, where the avoided crossing between the guided modes and the highest-index cladding mode of the real fiber is taken as the cut-off condition. A finite element-based full-vector modal solver has been applied to calculate the modes of DC-PCFs with different normalized air-hole size and core refractive index. Simulations have shown the possibility to find generalized results for the modal cut-off wavelengths of 19-cell DC-PCFs.

Published
2012
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81. Flexible cross-correlated (C 2 ) imaging method for the modal content characterization in a broad range of wavelengths.

Author

Muliar O, Usuga MA, Michieletto M, Kristensen T, Alkeskjold TT, Rottwitt K, and Lægsgaard J

Abstract

We demonstrate a flexible cross-correlated (C 2 ) imaging method in the time domain by application of a tunable and highly flexible light source. An advantage of the flexible C 2 method is shown by characterization of the step-index fiber (SMF28) over a broad range of wavelengths from 870nm to 1090nm and by the modal analysis of the distributed modal filtering (DMF) rod fiber within a wavelength range from 1050nm to 1090nm. Also, the influence of the spectral shape and bandwidth on the imaging trace is investigated by deliberately adjusting the input spectrum of the light source. The modal intensity as well as the phase distribution are extracted by the alternative method of 2D FT filtering. Being exceptionally tunable the flexible C 2 method gives an ability to adapt the system's parameters in a desired manner satisfying even measurements of very specific fiber designs opening up new possibilities for advanced modal characterization of fibers over broad range of wavelengths.

Published
2017
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