Search

An efficient strategy was established to optimize the performance of dye-doped host materials consisting of analyzing in a systematic way the dependence of their amplified spontaneous emission (ASE) efficiency and photostability on the composition and structure of the matrixes, selected to specifically avoid the thermal and/or chem. (photooxidation) processes, main mechanisms of dye photodegradation A number of exptl. polyimides were chosen as a host matrix and their behavior was compared with that of PMMA. The optical properties were correlated with the O permeation and thermal properties of the different polymeric hosts doped with perylene dyes to deepen the understanding of the photodegradation mechanism predominant in these dyes and to minimize its influence. High efficiency and photostable ASE from waveguides based on polymeric materials doped with Perylene Orange (PO), Perylene Red (PR), and mixtures of both are demonstrated. This enhancement in the optical properties allows reaching high gain and long-lasting distributed feedback (DFB) laser emission based on PO-doped polymer matrixes, even when operating in an unoptimized resonator., Spanish Ministerio de Economia y Competitividad (MINECO), Depto. de Química Orgánica, Fac. de Ciencias Químicas, TRUE, pub

A nucleophilic monomer (3,3'-diamino-4,4'-dihydroxybiphenyl, mHAB), isomer of the commercial 3,3'-dihydroxybenzidine (pHAB), has been synthesized in good yield and high purity by a two-step synthesis. This monomer was polymerized with 2,2'-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride(6FDA) to form a new ortho-hydroxy polyimide (mHAB-6FDA) followed by thermal rearrangement to polybenzoxazole in solid state. mHAB-6FDA polyimide film showed excellent film-forming ability and good mechanical properties, which were similar to those found for the isomeric polymer pHAB-6FDA. A detailed thermal study was carried out for both polymers (mHAB-6FDA and pHAB-6FDA) to discover the relationship between the thermal treatment employed and the degree of conversion to polybenzoxazole (PBO). Thermal rearrangement (TR) to PBO for the polymer derived from mHAB started from a lower temperature than for the polymer pHAB-6FDA. Final TR conversion was higher for pHAB-6FDA when the employed temperature and residence time were high enough; also, for any treatment temperature, fractional free volume (FFV) was higher for the polymer derived from mHAB. Gas separation properties were measured and it was found that gas permeability (and particularly CO2 permeability) was much better for the material made from mHAB. The high gas permeability along with good selectivity qualifies mHAB-6FDA as a good candidate in carbon capture applications. © 2013 Elsevier B.V.

We establish an efficient strategy to optimize the performance of dye-doped host materials consisting of analyzing in a systematic way the dependence of their Amplified Spontaneous Emission (ASE) efficiency and photostability on the composition and structure of the matrices, selected to specifically avoid the thermal and/or chemical (photooxidation) processes, main mechanisms of dye photodegradation. For this study, a number of experimental polyimides have been chosen as a host matrix and their behavior has been compared with that of poly(methyl methacrylate) (PMMA). We correlate the optical properties with the oxygen permeation and thermal properties of the different polymeric hosts doped with perylene dyes to deepen the understanding of the photodegradation mechanism predominant in these dyes and to minimize its influence. We demonstrate high efficiency and photostable ASE from waveguides based on polymeric materials doped with Perylene Orange (PO), Perylene Red (PR), and mixtures of both. This enhancement in the optical properties allows reaching high gain and long-lasting distributed feedback (DFB) laser emission based on PO doped polymer matrices, even when operating in an unoptimised resonator.

Long-lived amplified spontaneous emission (ASE) action is demonstrated in waveguides based in transparent newly synthesized fluorinated polyimides (FPI) doped with laser dye Pyrromethene 597. Relevant parameters to optimize the lasing performance of the guides are the polymer chain density and fluorine content. The guide with the higher fluorine content was themost stable,with the ASE emission remaining at 50% of its initial value after 40 000 pump pulses of 220 kW cm 2 delivered at a repetition rate of 5Hz. Net gains of up to 93 cm 1 were obtained at a pump intensity of about 500 kW cm 2 (34 mJ pulse 1).