NEAR-FIELD MEASUREMENTS OF OPTICAL CHANNEL WAVE-GUIDES AND DIRECTIONAL-COUPLERS

Near field microscopy is used to investigated the guided moded intensi ty distribution of optical channel waveguides and directional couplers with subwavelength spatial resolution. The directional coupler consis ted of two single mode optical ridge channel waveguides formed with si licon nitride deposited on a lower cladding layer of SiO2 on a silicon substrate. A near field measurement of the guided mode intensity prof ile in the transverse direction parallel to the waveguide surface was performed across one of the optical channel waveguides. These variatio ns are compared with model calculations. Similar transverse measuremen ts of light propagating through a directional coupler were performed a t many locations along the coupler, providing a view of the evolution of optical power transfer.