Interferometric optical-time-domain reflectometer to determine backscattering characterization of silica-based glass waveguides

An interferometric optical-time-domain reflectometer (OTDR) system with high spatial resolution has been developed for diagnosis of optical waveguides and hybrid optical circuits. A spatial resolution as short as 14 μm is obtained by using a newly developed 1.3-μm-wavelength superluminescent diode, and a minimum detectable reflectivity of −100 dB is achieved. Scattering centers that are produced by waveguide irregularities are clearly observed in silica-based glass optical waveguides, and the loss origin of the waveguides is discussed. Also, evaluation of other waveguide characteristics, such as modal birefringence and facet reflectivity, can successfully be made by the OTDR system.