Organic laser sources offer the opportunity to integrate flexible and widely tunable lasers in polymer waveguide circuits, e.g. for Lab-on-Foil applications. Therefore, it is necessary to understand gain and degradation processes for long-term operation. In this paper we address the challenge of life-time (degradation) measurements of photoluminescence (PL) and optical gain in thin-film lasers. The well known guest-host system of aluminum-chelate Alq<sub>3</sub> (Tris-(8-hydroxyquinoline)aluminum) as host material and the laser dye DCM2 (4-(Dicyanomethylene)-2- methyl-6-julolidyl-9-enyl-4H-pyran) as guest material is employed as laser active material. Sample layers have been built up by co-evaporation in an ultrahigh (UHV) vacuum chamber. 200nm thick films of Alq<sub>3</sub>:DCM2 with different doping concentrations have been processed onto glass and thermally oxidized silicon substrates. The gain measurements have been performed by the variable stripe length (VSL) method. This measurement technique allows to determine the thin-film waveguide gain and loss, respectively. For the measurements the samples were excited with UV irradiation (ƛ = 355nm) under nitrogen atmosphere by a passively Q-switched laser source. PL degradation measurements with regard to the optical gain have been done at laser threshold (approximately 3 μJ/cm<sup>2</sup>), five times above laser threshold and 10 times above laser threshold. A t<sub>50</sub>-PL lifetime of > 107 pulses could be measured at a maximum excitation energy density of 32 μJ/cm<sup>2</sup>. This allows for a detailed analysis of the gain degradation mechanism and therefore of the stimulated cross section. Depending on the DCM2 doping concentration <i>C</i> the stimulated cross section was reduced by 35 %. Nevertheless, the results emphasizes the necessity of the investigation of degradation processes in organic laser sources for long-term applications.
To integrate polymer fiber based physical layer for avionic data network, it is necessary to understand the impact and cause of harsh environments on polymer fiber optic components and harnesses. Since temperature and vibration have a significant influence, we investigate the variation in optical transmittance and monitor the endurance of different types of connector and splices under extreme aircraft environments. Presently, there is no specific aerospace standard for the application of polymer fiber and components in the aircraft data network. Therefore, in the paper we examine and define the thermal cycling and vibration measurement set up and methods to evaluate the performance capability of the physical layer of the data network. Some of the interesting results observed during the measurements are also presented.
By decreasing the arc power and choosing the optimal arc time, we use the FSM-20PM ARC Fusion Splicer for joining
fluoride(ZBLAN) and silica fibers. The best results of the splice loss is 1.58dB, and the results can be improved if the
Fusion Splicer with more stable arc power. Then glue connection is used to fix the splicing point, and the minimal loss
we measured is 0.14dB. The above results show that it is possible to connect the fluoride and silica fibers by using
Fusion Splicer with appropriate arc power and arc time, which will make the fabrication of these splices simpler and
easier to be handled.
Up-conversion fiber lasers based on Pr<sup>3+</sup>/Yb<sup>3+</sup> doped fluoride fibers and pumped at 835 nm can operate on emission lines in the red, orange, green, and blue spectral region. Up to now only Fabry-Perot configurations with two mirrors butt-coupled to the fiber ends were investigated. In this paper we present the first visible Pr<sup>3+</sup>/Yb<sup>3+</sup> fiber lasers in a ring configuration. In contrast to the usual Fabry-Perot configuration, the basic ring resonator setup contains no free-space optics and no parts which need to be adjusted. The main challenge for such a setup is the connection between the fluoride laser fiber and the remaining part of the ring resonator, which is made from silica fibers. Due to the very different melting temperatures of both glasses usual fusion splices are impossible. We use a special technique to couple the fibers with glue.