Plasmonic sensors have great potential for widespread usage, but the prohibitive cost of noble metals restrains the wider adoption of this technology. The aim of our study is to develop a cost-effective Al-based alternative to plasmonic detectors commonly based on noble metals. We considered a structure that consists of a Si p-n junction with an overlying grating-relief aluminum layer. The investigation of the infrared plasmonic resonance dependency on the structure geometric parameters and optimization of the fabrication process allowed us to determine optimal parameters for photodetection enhancement. The resonance photoresponse of optimized aluminum-based plasmon-polariton photodetector was significantly improved and became comparable to noble metal-based analogs. Our results can be used for the creation of cost-effective high-sensitivity plasmonic sensors.

The study of coherent vortices remains an urgent field of singular optics of vortex beams. In this paper, coherent properties of partially coherent vortex Bessel—Gaussian optical beams propagating through a uniform medium (free space) or a turbulent atmosphere are examined theoretically. The consideration is based on analytical solution of the equation for the transverse second-order mutual coherence function of the field of a partially coherent optical radiation in a turbulent atmosphere. For the partially coherent Bessel—Gaussian beam, the second-order mutual coherence function of the source field is taken as a Gaussian Shell-model. In this approximation, we analyze the behavior of the coherence degree and the integral coherence scale of these beams as a function of the propagation pathlength, propagation conditions, and beam parameters, such as the radius of the Gauss factor of the beam, parameter of the Bessel factor of the beam, topological charge, and correlation width of the source field of partially coherent radiation. In addition, the integral coherence scale of the partially coherent vortex Bessel—Gaussian beam is compared with that of the partially coherent Gaussian beam. It is found that as a partially coherent vortex Bessel—Gaussian beam propagates through a turbulent atmosphere, there appear not two (as might be expected: one due to atmospheric turbulence and another due to partial coherence of the source field), but only one ring dislocation of the coherence degree (due to the simultaneous effect of both these factors on the optical radiation). In addition, it is shown that the dislocation of the coherence degree that affects significantly the beam coherence level is formed only for beams, for which the coherence width of the source field is larger than the diameter of the first Fresnel zone.