Page 6 - PR 2014 2016 02 Lasers Technology
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20 Lasers Technology | Progress Report
- We also report resonant feedback random low cost and reduced dimension alternative
lasing from dye-doped biopolymer films, for laser devices and an ideal method for
consisting of a deoxyribonucleic acid-cetyl- crystallization studies. Fiber crystals are also
trimethylammonium (DNA-CTMA) complex particularly well suited for wave-guiding in
doped with DCM dye. The interesting feature the IR region, tunable narrow-band filters
about this random laser is that it works with and nonlinear optics due to their long inter-
a spatially localized feedback much alike a action length and tight beam confinement.
standard laser (Figure 2).
Fig 2 – Laser Resonator Schematics made of DNA
- We report an alternative experimental setup Rare earth doped tungstate single crystals
to laterally focus light at an angle of 90 deg have early gained attention because of their
relative to turbid, multiple scattering media, suitable properties for laser media applica-
using preprocessing wavefront shaping. We tion. However, many of the tungstate com-
compare the measured image quality to pounds undergo phase transitions and they
one obtained in the usual configuration for cannot be grown directly from their melts.
focusing light through turbid media, where Among the tungstate crystals, the compound
focusing occurs behind the scattering sample. LiLa(WO ) is one that have (has) a relatively
4 2
We demonstrate that the depth of focus in low melting point (1065 °C) and no phase
the lateral configuration is of the same order transitions upon cooling. We investigated
of the usual transversal one because both the growth process of Er /Yb :LiLa(WO )
3+
3+
4 2
setups are designed to operate in the deep single crystal fibers by the micro-pulling
Fresnel zone. This result shows that this nov- down method. The material’s synthesis by
el, versatile lateral configuration allows for solid-state reaction and the effect of different
effectively focusing around corners through dopant concentrations on the melting prop-
multiple scattering samples. erties were studied. The addition of Yb mod-
ifies the melting behavior of this compound
In order to obtain these lasers, the growth and LiLa Yb (WO ) single crystal fibers
(1-x) (x) 4 2
of crystal is an important activity in our can be grown up to limited Yb concentrations.
center. Single crystal fibers are known as a Single crystal fibers with 1 mm in diameter
Instituto de Pesquisas Energéticas e Nucleares
