Calorimetric measurement of LiNbO3 waveguide absorption losses

This paper reports the first measurement of optical‐absorption loss in LiNbO3 waveguides and bulk material. This is also the first demonstration of calorimetry as a feasible technique for measuring waveguide absorption in integrated optics. Results indicate that in LiNbO3 out‐diffused waveguides the absorption is two orders of magnitude lower than the total loss, implying that the predominant loss mechanism is scattering. The ultimate sensitivity limit for calorimetric determination of absorption losses appears to be ∼10−4 dB/cm for optimized geometries.