Plasmonic ultraviolet (UV) photodetectors have witnessed ongoing and tremendous enhancements in quantum efficiency and responsivity. Here, we go beyond regular plasmonic detectors by using periodic arrays of fractal aluminum nanostructures as Cayley trees deposited on a Ga<sub>2</sub>O<sub>3</sub> substrate to generate photocurrent. We show that the proposed aluminum Cayley trees are able to support and intensify strong broad plasmon resonant modes across the UV to the visible spectrum. It is shown that the Cayley trees can be tailored to facilitate strong absorption at high energies (short wavelengths), resulting formation of hot carriers. Having perfect compatibility to operate at the UV spectrum, fractal aluminum structures and Ga<sub>2</sub>O<sub>3</sub> substrate help to increase the produced photocurrent remarkably. Presence of Ga<sub>2</sub>O<sub>3</sub> layer blue-shifts the peak of absorption to higher energies and helps to generate hot carriers at deeper UV wavelengths.
We introduce a platform based on plasmonic metamaterials to design various optical devices. A simple structure brokenring
with a nanodisk at the center is utilized to excite and hybridize the plasmon resonant modes. We show that the
proposed nanoantenna is able to support strong sub- and superradiant plasmon resonances because of its unique
geometrical features. Using the concentric ring/disk in a dimer orientation as a nanoantenna on a multilayer metasurface
consisting of graphene monolayer, we induced double sharp plasmonic Fano resonant modes in the transmission window
across the visible to the near-infrared region. Considering the strong polarization-dependency of the broken-ring/disk
dimer antenna, it is shown that the proposed plasmonic metamaterial can be tailored as an optical router device for fast
switching applications. This understanding opens new paths to employ plasmonic metamaterials with simple geometrical
nanoscale blocks for sensing and switching applications.