title: Refractive-index profile measurement of highly multimode planar waveguides by guided-beam tracking.
abstract: A novel method of measuring the refractive-index profile of deep multimode planar waveguides is described. Unlike in mode spectroscopy, several modes are excited simultaneously by a prism coupler. Superposition of the modes forms a guided beam that refracts continuously inside the graded-index waveguide and reflects periodically from the waveguide surface. Measurement of the periodicity as a function of the excitation angle enables one to calculate the refractive-index profile of the waveguide.
authors.forename: J
authors.initials: J
authors.lastname: Ctyroký
authors.forename: J
authors.initials: J
authors.lastname: Janta
authors.forename: J
authors.initials: J
authors.lastname: Schröfel