US 7,469,084 B2
	Structure comprising an adiabatic coupler for adiabatic coupling of light between two optical waveguides and method for manufacturing such a structure
Timo Aalto, Espoo (Finland)
Assigned to Valtion Teknillinen Tutkimuskeskus, Espoo (Finland)
Appl. No. 11/579,581 PCT Filed May 18, 2004, PCT No. PCT/FI2004/000299 § 371(c)(1), (2), (4) Date Jul. 19, 2007, PCT Pub. No. WO2005/111680, PCT Pub. Date Nov. 24, 2005.
Prior Publication US 2007/0286552 A1, Dec. 13, 2007
Int. Cl. G02B 6/26 (2006.01); G02B 6/30 (2006.01); G02B 6/10 (2006.01)

U.S. Cl. 385—50  [385/28; 385/43; 385/49; 385/130]

21 Claims

1. 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 (g5) 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.