Abstract: An interface device for performing off-chip coupling in optical waveguides includes an optical waveguide core for propagating light of a particular wavelength or a plurality of wavelengths and an array of radiative elements configured to change the propagation direction of the light. The optical waveguide core is configured to control the effective refractive index of the propagation mode of the light. The device can thus serve as an optical antenna for coupling between a waveguide mode and a free-space propagating beam or a plurality of free-space propagating beams in an arrayed configuration.

Abstract: An antenna device for performing off-chip light coupling comprising an array of radiating elements whose thickness is larger than ?/2, the radiating elements being chosen such that the length of the array is smaller than 10?, where ? is the wavelength of light in the material chosen for the radiating elements. An advantage of this method is that, unlike in conventional waveguide grating antenna, by reducing the number of the radiating elements in the array, the dependence of the off-chip emission angle on the wavelength of light can be greatly reduced. Another advantage is that by using thick radiating elements the antenna efficiency can be greatly enhanced, thereby compensating for the reduced efficiency occurring as a consequence of using only a small number of radiating elements in the array.

Abstract: A waveguide cores consisting of a subwavelength grating permits transmission of light without diffraction in a discontinuous manner, wherein the energy is provided by field hopping between subwavelength material segments of higher index. The use of alternating segments permits design of waveguides having desired effective index, mode confinement factor, birefringence, polarization mode or mode dispersions, polarization dependent loss, thermal sensitivity, or nonlinear optical coefficient. An optical system comprises a waveguide having such a core, clad on at least one side, extending between two ends, and wavelength-limiting optical components in optical communication with the ends.

Abstract: A waveguide cores consisting of a subwavelength grating permits transmission of light without diffraction in a discontinuous manner, wherein the energy is provided by field hopping between subwavelength material segments of higher index. The use of alternating segments permits design of waveguides having desired effective index, mode confinement factor, birefringence, polarization mode or mode dispersions, polarization dependent loss, thermal sensitivity, or nonlinear optical coefficient. An optical system comprises a waveguide having such a core, clad on at least one side, extending between two ends, and wavelength-limiting optical components in optical communication with the ends.