Patent ID: 6229947
Filing Date: 2001-05-08
Classification: G02B,H01S

Abstract:
An adiabatic tapered rib coupler to an optical fiber for use with a cutoff mesa waveguide semiconductor optical device, wherein the cutoff mesa waveguide optical device comprises a first isolated rib structure having opposing side walls of height h and a width w1, the first isolated rib being centrally located above a mesa structure located above a substrate which mesa structure has an output face at one end with the first isolated rib structure being terminated short of the output face of the mesa structure, such that only the fundamental optical mode is allowed to propagate within the device and wherein the fundamental mode has its region of maximum intensity bound to the first isolated rib structure, the tapered rib coupler comprising:a tapered rib structure located above the mesa and aligned with the first rib structure and having side walls of height h, the tapered rib structure having a tapered portion with a first end of width w1 monolithically connected to the termination of the first rib structure and a second end of width w2, where w2<w1, wherein the decrease in width between w1 and w2 is sufficient to force at least 80% of the light in the fundamental mode that was bound to the first isolated rib structure down into the mesa while remaining aligned with the tapered rib structure; andthe mesa structure having a height and width so as to match the effective aperture of the optical fiber and a composition such that only a single local maximum refractive index region proximate to the upper surface of the mesa is present but with the center of the fundamental mode on the output face of the mesa being located below the maximum refractive region.