Nondestructive and simple method of optical-waveguide loss measurement with optimisation of end-fire coupling

Abstract

The Letter proposes and demonstrates a nondestructive and simple method for optical-waveguide loss measurement in which the end-fire coupling efficiency is optimised so that an input beam spot size becomes exactly the same as the mode size of a guided wave. An accuracy of better than 0.05 dB/cm has been achieved in Ti: LiNbO3 waveguides.