Investigation of parameters of thin films deposited on planar waveguides

Using the method of m-line spectroscopy [1] it is possible to determine parameters (thickness and refractive index) of thin films deposited on planar waveguides through indirect measurement of changes of coupling angle to the waveguide. The subject of the study were thin organic films deposited on waveguides by casting diluted polymerizable solutions, and by spin-coating thin polyimide films. These films are developed as active coatings in waveguide sensors. Numerical calculations (applied for three-layer structures) after modification to a four-layer structure allows for determining the parameters of thin films.