it is possible that the long waveguide eventually actually acts as a cladding for the waveguide application_number US 47394602 A description the following description will further help to explain the inventive features of the high efficiency optical mode transformer for matching a single mode fiber with a high index contrast planar waveguide on a microchip the approach used in this invention is to separate the problem into two steps with definitive objectives the first objective is to get optical power from the sm fiber onto the chip but not into the hc guide with the highest possible efficiency once high efficiency connectivity and optical power transmission is established onto the chip power is then transferred into the hc waveguide via an on chip mode transformer a large planar waveguide is fabricated on the chip for the purpose of obtaining maximum coupling efficiency from a fiber to a specific structure on the chip the dimensions of the large waveguide are chosen so as to achieve maximum coupling efficiency this waveguide is referred to as a fiber matched waveguide an optical mode transformer on the chip then converts the optical power in the fiber matched waveguide into the hc waveguide for the present invention the onchip fiber matched waveguide has a fundamental.