Photonic apparatus for controlling polarization

A polarization-sensitive photonic splitter comprising:

• a lower cladding layer;
• a device layer disposed on the lower cladding layer, the device layer extending in a plane and having a thickness direction normal to the plane, the device layer comprising:
• a first waveguide formed from a first waveguide core bounded by cladding in the plane of the device layer, wherein the first waveguide supports TE and TM light within a selected operational wavelength range;
• a second waveguide formed from a second waveguide core bounded by cladding in the plane of the device layer;
• a third waveguide formed from a second waveguide core bounded by cladding in the plane of the device layer, wherein the first waveguide core and the second waveguide core are formed from one of a first core structure or a second core structure, wherein the third waveguide is formed from the other of the first core structure or the second core structure, wherein the first core structure is formed as a material having an index of refraction nM, wherein the second core structure is formed as alternating layers of a first material having a first index of refraction and second material having a second index of refraction that is different than the first material, the alternating layers arranged in a periodic structure with a periodicity along the thickness direction, the alternating layers providing an effective index of refraction for TE polarized light nTE and an effective index of refraction for TM polarized light nTM, wherein nTM<nM<nTE for light having wavelengths within an operational wavelength range;
• and
• a transition core formed from the first core structure adjacent to the second core structure, wherein the transition core is coupled to the first waveguide at a first end of the transition core, wherein a width of the transition core at the first end is equal to a width of the first waveguide, wherein a width of the transition core at a second end is equal to a sum of a width of the second waveguide and a width of the third waveguide, wherein a portion of the transition core formed from the first core structure is coupled to the second waveguide at the second end of the transition core, wherein a portion of the transition core formed from the second core structure is coupled to the third waveguide at the second end of the transition core.