We develop photonic funnels, structures that provide efficient optical coupling between nano- and micro-worlds. The funnels represent conical waveguides with highly anisotropic cores and highly conductive cladding that have one opening with crossection of the order of free space wavelength and the second opening with deep subwavelength crossection. We fabricate all-semiconductor photonic funnels at mid-infrared frequency range and demonstrate, theoretically and experimentally, efficient confinement of mid-infrared light to wavelength/30 areas. Theoretically, we predict efficient out-coupling of light from ultra-small areas to diffraction-limited domain.
We analyze the mid-infrared emission resulting from the interplay between a type-II superlattice (T2SL) material and semiconductor-based plasmonic “designer metals”. We demonstrate an order of magnitude emission enhancement, accompanied by spectral reshaping, relative to all-dielectric T2SL counterparts and provide a theoretical description of the underlying physics. The all-semiconductor LWIR emitters with integrated plasmonic components, developed in this work, represent novel approach to broadband room-temperature mid-IR sources.