Concentration effects in the photodegradation of lissamine-functionalized neodymium complexes in polymer waveguides

The photodegradation of lissamine-functionalized Nd complexes doped at a concentration of 10 wt. % in a fluorinated polycarbonate waveguide has been studied. On illumination at 458 nm and at 488 nm, the luminescence spectrum of the lissamine sensitizer shifts to shorter wavelengths, while the luminescence intensity first increases and then decreases. The spectral shape of the Nd luminescence does not change on illumination, and the luminescence intensity shows a gradual decrease as a function of time. The difference in response between the lissamine and the Nd luminescence can be described by a model that assumes the existence of two different types of complex. One type exhibits energy transfer from the lissamine to the neodymium ion, with a large lissamine intersystem crossing rate, and hence low sensitivity to concentration quenching. The other type does not show energy transfer to Nd, and does experience concentration quenching.