NONDESTRUCTIVE WAVE-GUIDE LOSS-MEASUREMENT METHOD USING SELF-PUMPED PHASE-CONJUGATION FOR OPTIMUM END-FIRE COUPLING

We present a new nondestructive method for measuring the propagation l oss coefficient in waveguides based on optimum end-fire coupling by se lf-pumped phase conjugation in a photorefractive BaTiO3 crystal. In a first pass through the waveguide, the laser beam is adapted to the wav eguide mode profile, and hence the phase-conjugated beam is automatica lly coupled back into the guide with the optimum coupling efficiency. The propagation loss coefficient is determined by measurement of the t ransmittance of the phase-conjugated beam in the second pass through t he waveguide. We apply this method to measure the propagation loss coe fficient of ion-implanted KNBO3 channel waveguides with an accuracy of better than 5%. (C) 1995 Optical Society of America