Patent ID: 8483528

Claim:
An optical mode transformer comprising: a first waveguide extending along a first main longitudinal direction and including an end facet configured to be coupled to an optical fiber, the first waveguide including a first core and a first cladding, and having a first refractive index contrast; and a second waveguide being arranged with respect to the first waveguide so as to realize an evanescent optical coupling with the first waveguide, the second waveguide comprising a second core and a second cladding, and having a second refractive index contrast, the second core including a tapered region in at least a portion of which the evanescent coupling takes place; and wherein the first core and the second core are separated by a gap, the first refractive index contrast is less than the second refractive index contrast and the second refractive index contrast is not less than 18%.