Modified Duc de Chaulnes' method for measurement of mode indexes of semiconductor slab waveguides

For measuring mode indexes of AlGaAs waveguides, a modified Duc de Chaulnes method, which is noncontact, nondestructive, and applicable to high index as well as buried waveguide, is proposed and discussed. Mode indexes are measured by reference to the substrate index by comparing waveguide and substrate in the displacement of image. Measurement accuracy is improved in comparison with the conventional Duc de Chaulnes method. From experimental work on the identification accuracy of the imaging objective position, it was confirmed that the error in the mode index was smaller than 0.2%.<
>