Patent ID: 7469084

Claim:
A structure comprising an adiabatic coupler for adiabatic coupling of light between two optical waveguides ( 1 , 2 ), said structure comprising an inner waveguide ( 1 ) disposed inside the structure and an outer waveguide ( 2 ) disposed on top of and longitudinally in alignment with the inner waveguide ( 1 ), each of the inner and outer waveguides having a refractive index of at least 2.5 and being arranged on a common planar substrate, wherein the inner waveguide ( 1 ) is a strip waveguide having a substantially rectangular cross-section and patterned into an inner core layer ( 3 ); that the outer waveguide ( 2 ) is a rib waveguide which is thinner than the inner waveguide and patterned into an outer core layer ( 4 ), and that the cores of the inner and outer waveguides are separated by a gap ( 5 ) the thickness (g 5 ) of said gap ( 5 ) being less than 500 nm, whereby the optical power is coupled from one waveguide to another by changing the width of at least one of the waveguides forming thereby a longitudinal coupling region along the coupler.