Nondestructive measurement of separated propagation loss for multimode waveguides

We propose a method which applies a combination of the well-known phase modulator, butt-couple and prism coupler to the nondestructive measurement of each mode's propagation loss in multimode waveguides. By tuning to the effective optical length of a channel waveguide with a phase modulator, the contrast in the transmitted intensity of Fabry-Perot resonance for each guided mode separated by a prism coupler can be measured. The associated propagation attenuation coefficient and the propagation loss for each guided mode are then determined from these experimental results.