Losses in very large planar waveguides

Planar optical waveguides with linear dimensions exceeding one metre, are readily available as a byproduct of standard glass processing treatments. Measurements of the mode distribution and losses in such guides are reported for two types of float glass. Typically, the layers support one or two modes. Losses were noted to be as low as 0.3 dB/cm. A possible source of error for planar guide losses in conventional samples is discussed.