Amplified Spontaneous Emission from the Monomer of a Conjugate Polymer by Energy Transfer Process

Abstract

Conjugate polymers are recognized as remarkable optically pumped laser media. Their spectral and laser characteristics are similar to those of dye laser media, but they are superior in performance. In this study, amplified spontaneous emission (ASE) has been obtained from two sets of solutions, one containing Coumarin 485 (C485) as a donor and poly[2-methoxy-5-(20-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV) as an acceptor and another containing MEH-PPV as a donor and laser dye 700 (LD 700) as an acceptor. A high power neodymium-doped yttrium aluminium garnet (Nd:YAG) laser at 355 nm produces the excitation of these laser media. Depending upon the concentration and pump energy, ASE was obtained at 485 nm from C485, at 700 nm from LD 700, or at 600 nm from the MEH-PPV aggregate, or at 560 nm from the unaggregated, monomeric form of MEH-PPV or a combination of the above. The ASE spectra give new insight into the excited-state dynamics of these conjugate polymers. This study shows that the energy transfer interaction is necessary for obtaining laser action from the unaggregated MEH-PPV.