Variable Optical Mode Generator in a Multimode Waveguide

A variable optical mode generator in an integrated-optic multimode waveguide is proposed and fabricated. It consists of a power divider, controllable parallel phase retarders, and a mode combiner. In this device, a desired output mode is generated by controlling the relative phase differences among the arms. The operation of device has been confirmed by observation of the output mode patterns at a wavelength of 1.55
$ mu$
m.