We demonstrate laser emission in polymer-based microrings doped with a near infrared emitting dye, 2-(6-(4-Dimethylaminophenyl)-2,4-neopentylene-1,3,5-hexatrienyl)-3-methyl-benzothiazolium perchlorat. We fabricate our poly(1-vinyl-2-pyrrolidone)-based microrings containing 0.5 wt % of the dye. They exhibit lasing at around 840 nm under transverse nanosecond photoexcitation at 532 nm. Optical feedback is provided by total internal reflection. The threshold for lasing is found to be 311 μJ/cm2. The cavity has a Q-factor larger than 2000, which is limited by the resolution of our detection system.
We study light amplification and laser emission in polymer gain media containing a near-infrared emitting dye, 2-(6-(4-dimethylaminophenyl)-2,4-neopentylene-1,3,5-hexatrienyl)-3-methyl-benzothiazolium perchlorat, with a view to the development of polymer amplifiers and lasers operating in the 800-nm region of the spectrum. Nanosecond gain spectroscopy is carried out by use of amplified spontaneous emission. Multimoded poly(1-vinyl-2-pyrrolidone)-base planar waveguides, 50 μm in thickness, doped with 0.5 wt% dye show a moderate net small-signal gain coefficient of 2.6±0.3 cm-1 (11.3±1.3 dB/cm) at 820 nm for the pump fluence of 115 μJ/cm2 (23.1 kW/cm2). Moreover, we have fabricated polymer microring cavities 200 μm in diameter with the same material composition. The moderate optical gain in the material allows laser emission to occur at around 840 nm under transverse nanosecond photoexcitation at 532 nm. The threshold for lasing is found to be 311 μJ/cm2 (62.2 kW/cm2).
We present the results of a study of the optical properties of an organic dye, (1,4-Bis[2-[4-[N,N-di(p-tolyl)amino]phenyl]vinyl]benzene)-doped polymer for photonic device applications. We have measured considerable modal gains of up to 33 cm-1 at 501 nm at a range of pump fluences using the variable stripe length method. In addition, we have incorporated the material into a planar waveguide laser, which operates at a low-lasing threshold. The measured laser threshold agrees well with that predicted for a 1-cm Fabry-Perot type cavity. We have also made 80-micron diameter microrings, which operate at a low lasing threshold and exhibit lasing in a small number of narrow, well-defined cavity modes.
A derivative of poly (m-phenylene vinylene-co-2, 5-dioctyloxy-p-phenylene vinylene) is synthesized using two types of condensation polymerisation reactions, namely Horner-Eammons and Wittig, in three different solvents, toluene, dimethhylformamide (DMF) and chlorobenzene. Although the derivatives formed by each reaction have the same chemical composition it is found that their chemical and optical properties vary. NMR studies show that the morphologies of the polymers are different, due to the differences in cis-trans bond ratio of the vinylene bonds. It is found that the derivatives produced by Horner condensation contain a majority of trans bonds and these derivatives show different spectral characteristics to the Wittig derivatives. The ability of the polymers to disperse carbon nanotubes is also studied. Here, not only is the synthetic route important, but the solvent used also plays a role. The derivatives that are produced by the Horner condensation route in DMF or chlorobenzene are found to have the best binding capabilities with carbon nanotubes.
Amino functionalized multi wall carbon nanotubes (MWNT) were reacted with an inorganic Ruthenium complex, {[Ru(dcclbpy)(bpy)2](PF6)2}, in an attempt to covalently attach the Ruthenium complex to the MWNT. The covalent attachment between the Ruthenium complex and the carbon nanotubes is achieved by the formation of an amide group. Absorption and emission spectroscopy indicated that a reaction between the amino functionalized MWNT and the Ruthenium complex occurred. Atomic fore microscopy (AFM) images gave further evidence of a successful attachment of the Ruthenium complex to MWNT by showing multiple junctions between MWNT distinct from naturally occurring splitting of MWNT ropes.
Zinc-2, 9,16,23 -tetra- tert-butyl-29H, 31H -phthalocyanines and Zinc-2, 9,16,23-tetrakis-(phenylthio)-29H, 31H-phthalocyanines were recrystallized from an acetone solution to give regular shaped spherical particles of 50nm diameter, confirmed by transmission electron microscopy (TEM) and atomic force microscopy (AFM). A peak broadening of the Q-Band and a shift of the B-Band in the UV-Visible absorption spectrum combined with a significant fluorescence quenching was observed. The z-scan technique was used to investigate the non-linear optical properties and an increase of approximately 200% in the ratio of excited to ground state absorption cross sections in the crystal state was observed indicative of a significant increase in the optical limiting response of the crystals compared to the monomers.
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