Photothermal beam deflection techniques: Useful tools for integrated optics

Photothermal beam deflection spectroscopy (PTBDS) is used together with waveguide loss measurements to distinguish between intrinsic, absorptive and scattering losses in polymeric waveguide materials. Overtones of vibrational modes of organic waveguide materials in the near infrared spectral regime can be distinguished very precisely with PTBDS. In an example of different polythiophens, we demonstrate the influence of the side chains (CH2- and CH3-vibrations) and the conformation of the main chain on the absorption spectrum in the spectral regime of optical telecommunication. The photothermal beam deflection method is also used for imaging waveguide structures and to investigate order parameters of dyes within a polymeric matrix.