The ever increasing rates of data transmission around the globe drive conventional electronic
computer chips for information processing towards their limits [1, 2]. New concepts are
required, capable of providing fast and broadband signal processing while keeping costs and
energy consumption at a minimum. Indeed, optical chips constitute a good solution to this
problem but suffer from size restrictions as their device features need to be larger than the
wavelength of light. Photonic-plasmonic hybrid systems constitute a viable alternative to
overcome this obstacle, consisting of low-loss dielectric transmission lines interlinked with
compact plasmonic devices capable of communicating with electronic transistors. In these
devices, efficient energy conversion from the microscopic optical domain to the nanoscopic
electronic domain is key to render next generation computing platforms possible. Hence,
this work examines low-loss conversion from the photonic to the plasmonic regime which
allows to focus light below its diffraction limit by coupling directly to collectively oscillating
electron distributions, called surface plasmons.
Here, a Si-compatible nanofocusing platform is investigated, which enables to produce
large field intensities in tens of nm3 volumes and allows to direct energy into and out-of
sub-wavelength scaled plasmonic waveguides. For the first time, an incoupling efficiency
exceeding 80% is demonstrated. Furthermore, efficient nano-de-focusing is successfully
exploited for the first time to enhance photoluminescence of Er3+-ion emitters placed in a
HGPW geometry. This constitutes a promising approach for room-temperature single-photon
emission and on-chip signal processing as Er3+ emits at telecommunications wavelength.
Closely related to on-chip signal processing is opto-electronic sensing and light detection.
However, solid state sensors are generally bandgap energy limited. Here, we investigate hotcarrier
Schottky barrier junctions which work via carrier excitation at a metal/semiconductor
interface with sufficient energy to surpass a Schottky barrier (SB) while not being
limited by the bandgap. The successful implementation of a self-powered, Si-compatible hotcarrier
infrared SB detector is demonstrated. Titanium nitride is used which strongly boost
the response, originating in a thin TiO2−x interlayer as demonstrated for the first time.