RESUMEN
Silicon T centers present the promising possibility of generating optically active spin qubits in an all-silicon device. However, these color centers exhibit long excited state lifetimes and a low Debye-Waller factor, making them dim emitters with low efficiency into the zero-phonon line. Nanophotonic cavities can solve this problem by enhancing radiative emission into the zero-phonon line through the Purcell effect. In this work, we demonstrate cavity-enhanced emission from a single T center in a nanophotonic cavity. We achieve a 2 order of magnitude increase in the brightness of the zero-phonon line relative to waveguide-coupled emitters, a 23% collection efficiency from emitter to fiber, and an overall emission efficiency into the zero-phonon line of 63.4%. We also observe a lifetime enhancement of 5, corresponding to a Purcell factor exceeding 18 when correcting for the emission to the phonon sideband. These results pave the way toward efficient spin-photon interfaces in silicon photonics.
RESUMEN
An ultra-broadband perfect absorber has a wide range of applications which include solar energy harvesting, imaging, photodetection etc. In this regard, InAs nanowire (NW) based structure is investigated in this work for achieving an ultra broadband perfect absorber. Finite difference time domain (FDTD) based numerical analysis has been performed to optimize the InAs nanowire based structure to obtain an efficient light absorber by varying different dimensional parameters. Mie theory and guided mode resonance based theoretical analysis is developed to validate the results and to get an insight into the tunability of the nanowire based structure. Moreover, the theoretical analysis elucidates the underlying physics of light absorption in nanowires. To achieve ultra broadband absorption, multi radii InAs nanowire based arrays are investigated and it is found that they exhibit superior performance compared to single radius NW based structures. The computed light absorption efficiency (LAE) and short circuit current density values are enhanced to 97% and 40.15 mA cm-2 at 10° angle of incidence for the optimized quad radii NW array within the wavelength range of 300 nm to 1000 nm and 300 nm to 1200 nm, respectively. Moreover, the absorption spectra for these structures are polarization independent and exhibit robust performance for varying angle of incidence. In addition, arrangement of the NW array (hexagonal or square) has negligible effect on the absorption spectra. Such ultra-broadband absorption capability of the proposed structure compared to existing works suggests that the InAs nanowire based structure is very promising as light absorber with prospects in the fields of photo detection, solar power generation, perfect cloaking, photochemistry and other thin film photonic devices.
RESUMEN
Due to changes in our climate and constant loss of habitat for animals, new pathogens for humans are constantly erupting. SARS-CoV-2 virus, become so infectious and deadly that they put new challenge to the whole technological advancement of healthcare. Within this very decade, several other deadly virus outbreaks were witnessed by humans such as Zika virus, Ebola virus, MERS-coronavirus etc. and there might be even more infectious and deadlier diseases in the horizon. Though conventional techniques have succeeded in detecting these viruses to some extent, these techniques are time-consuming, costly, and require trained human-resources. Plasmonic metamaterial based biosensors might pave the way to low-cost rapid virus detection. So this review discusses in details, the latest development in plasmonics and metamaterial based biosensors for virus, viral particles and antigen detection and the future direction of research in this field.