Sponsor: Czech Science Foundation
Principal investigator: Vlastimil Matějec, Ph.D.
Members: Jan Aubrecht, Ph.D.; Ivo Bartoň, MSc.; Ivan Kašík, Ph.D.; Jan Mrázek, Ph.D.; Ondřej Podrazký, Ph.D.
From: 2012-01-01
To: 2015-12-31
The aim of the project is the design, preparation and characterization of Bragg fibers with an air core for the transmission of high-energy laser radiation in the spectral region around 1,060 nm and for the generation and transmission of laser radiation in the region around 1550 nm. Such fibers represent alternative fibers with internal metallic reflection layer used in medicine for the transmission of laser radiation. The photonic banned Bragg gap is used for the transfer of radiation in the 1,060 nm used on the fibers in this project. The loss of radiation from the nucleus to the multilayer packaging at 1,550 nm will be offset from the optical gain obtained on erbium ions pumped through ytterbium ions.
Bragg fiber structure consisting of three pairs of high- and low- index layers with refractive index contrast to 0.04 were designed in the first two years of the project. The preforms were prepared from silica glass doped with germanium oxide by the method of chemical vapor deposition (MCVD) and from that three types of Bragg fiber were extracted (see illustration in Fig. 1)
Fig. 1. Cross sections of the prepared Bragg fibers; A- fibers with a silicia core (ɸ~26µm), B- fiber with a small air core (ɸ~5µm), C- fiber with a large air core (ɸ~72µm).
The fibers were characterized at 1064 nm by measuring the transmittance attenuation and their sensitivity to bending was measured with the use of the CCD camera output profiles bundles of fibers in the far field. They were also tested for their properties for the transfer of energy pulsed Nd: YAG laser at 1064 nm. Examples of the measured results are shown in Tab. 1.
Tab. 1 : Measured characteristics of the prepared Bragg fibers at 1064 nm
So far, the results of the project show that the prepared fiber can be used in lengths of tens of meters for the transmission of high-energy pulsed lasers.
References:
