Polymer lasers

C. Kallinger, M. Hilmer, A. Haugcneder, M. Pemer, W. Spirkl, U. Lcmmer. J. Feldmann, U. Scherf, K. Mullen, A. Gombcrl, V. Wiltwer, Flexible conjugated polymer laser, Adv. Mater. 1998, 10, 920. 

D. Moses, High quantum efficiency luminescence from a conducting polymer in solution a novel polymer laser dye. Appl. Phys. Leu. 1992, 60, 3215. 

Polymer laser diodes have been an attractive topic after the discovery of EL in conjugated polymers. Optical lasing in semiconducting luminescent polymer solutions was first... 

C. Bauer, H. Giessen, B. Schnabel, E.-B. Kley, C. Schmitt, U. Scherf, and R.F. Mahrt, A surface-emitting circular grating polymer laser, Adv. Mater., 13 1161-1164, 2001. 

All systems presented in this section show lasing only in the optical pumping mode. There is much interest in electrically pumped devices, but for molecular glasses the difficulties in achieving high excitation densities and low absorption due to charge carriers and electrodes have yet to be overcome. This problem and the related semiconducting polymer lasers that are based on the same principles will not be covered here, but are treated in recent reviews [214-216]. 

At the present time, the lasing threshold of the best polymer lasers is approaching that of the output of a blue emitting InGaN LED. Thus, it may soon be possible to place polymer lasers onto InGaN LEDs, which would be used to optically pump the polymer lasers. By using several different polymers on the same substrate, a monolithic structure that would lase at colors spanning the entire visible spectrum could be made. 

A more direct route to making polymer lasers would be to excite the polymers electrically in a diode structure. Although polymer LEDs have been made in which the injected carrier density matches the threshold excitation density of the best photopumped polymer lasers, a polymer diode laser has not yet been made. The threshold for diode lasers is higher because the electrodes that must be incorporated to the structure increase the waveguiding loss. In addition, for some... 

Silicone Polymers - Laser flash photolysis studies on poly(silylenes) generates radical cations along with silyl radicals and polysiloxane composities for the space shuttle have been found to be stable to far UV light exposure. Linear polysiloxanes have been found to be more unstable than branched or crosslinked polymers while the transparency of poly(methylphenylsilane) increases with light exposure. Photooxidised polysiloxanes doped with iodine are converted into semiconductors. ... 

Phenylene-based polymers are one of the most important classes of conjugated polymers, and have been the subject of extensive research, in particular as the active materials in light-emitting diodes (LEDs) [1,2] and polymer lasers [3]. These materials have been of particular interest as potential blue emitters in such devices [4], The discovery of stable blue-light emitting materials is a major goal of research into luminescent polymers [5]. Poly(para-phenylene) (PPP, Scheme 1, 1) is a blue emitter [6], but it is insoluble and so films of PPP have to be prepared via precursor routes [7]. Substitution with long alkyl... 

Silicone Polymers - Laser flash photolysis of poly(methylphenylsilylene) gives a transient absorption associated with exciton states while fullerene reduces bond scission in polysilanes. ... 

The flexibility of the substrate, the ease, and the low costs of fabrication of this DFB-polymer laser offer a very promising way to novel surface-emitting laser devices which take full advantage of the properties of conjugated polymers. 

Fig. 86 Fluorescence spectra of a pyrene-implanted PBMA surface as a function of laser pulse number. Pyrene was transferred using ablation of a triazene polymer. Laser flu-ence 100 mj creT2, (a) 5 pulses, (b) 10 pulses, (c) 15 pulses, (d) 20 pulses. The vibrational pyrene emission peaks are denoted (I-V). Inset Normalized fluorescence intensity of the V pyrene peak at 393 nm vs laser pulse number. Data are taken from the spectra in the main figure. REPRINTED WITH PERMISSION OF [Ref. 360], COPYRIGHT (1998) Elsevier Science...

Interestingly, Vg-controlled electroluminescence and ambipolar characteristics have been recently observed in conjugated polymer OFETs [67,68], which indicates a balanced electron and hole injection. However, low hole and electron mobilities ( 10 cmWs), typical for polymer semiconductors, limit the channel current and therefore may present a serious problem for realizatiou of electrically pumped polymer lasers. For this reasou, ordered smaU-molecule orgauic semicouductors with higher mobilities are very promisiug for research in this direction. 

One of the most fascinating developments in recent times concerns the generation of light with the aid of polymers. This development is characterized by two inventions, which are described in the following subsections the polymeric light-emitting diode and the polymer laser. 

Fig. 6.16 Schematic iiiustration of a fiexibie polymer laser device consisting of an m-LPPP layer spin-coated onto a two-dimensionally structured flexible poly(ethy-lene terephthalate) substrate. The laser light...

I. D. E. Samuel, G.A. Turnbull, Polymer Lasers Recent Advances, Materials Today 7 (2004) 28. 

A potential application of polymer laser ablation concerns the propulsion of small satellites (1-10 kg) used in space science [86]. Laser plasma thrusters, LPTs, operating with small, powerful diode lasers emitting in the near-infrared wavelength range (930-980 nm) have been proposed. Polymers intended to serve as fuel for a thruster are required to possess a large momentum coupling coefficient, C, defined by Eq. (9-3) ... 

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