Infrared image analysis as a new experimental approach for measuring waveguide losses

In this paper, we report a new method for measuring the waveguide losses based on infrared (IR) imaging. Since light absorption induces a temperature increase along the light propagating path inside the waveguide, we tried to use a thermal camera in order to monitor the waveguide losses. We measured the losses of the same planar waveguide also with a traditional method using an external optical fibre to collect the scattered light as a comparison. The value of the losses measured with such an approach is in good agreement with our measurements based on the thermal analysis of IR images. Furthermore, we propose our method also to optimize the coupling efficiency by monitoring the light coupled as a function of the mechanical pressure on the prism. It represents a very simple tool to enhance the light coupling by varying the pressure on the prism used for launching the light inside the waveguide. We believe that our method could be very useful to measure the waveguide losses on a large scale for the industrial production of guiding structures. © 2009 IOP Publishing Ltd.