Waveguide Attenuation Characterisation by the Mirage Effect

We demonstrate a new destruction-free method for the investigation of waveguide losses. Typically the intensity profile is measured directly or the scattered light is imaged. Here we contactless measure the photothermal response due to intrinsic absorption of the waveguide material in front of the propagating mode. The experimental setup and measurements, including an estimation of the expected resolution, are given.