We present a novel optical sensor platform designed for the detection of medical biomarkers. The sensor operates by utilizing reflection variation resulting from the modification of Fano resonance conditions. By fabricating one- and two-dimensional subwavelength quasi-periodic structures made of polymer and coated with an inorganic layer, we enable the functionality of the sensor, ultimately leading to increased sensitivity and detection threshold. The development of the sensor’s platform involves a multi-step process. The detection mechanism primarily relies on the optical response of the biosensor. The presence of analytes induces a spectral shift of the Fano resonance, which is caused by the modification of the biolayer thickness. This optical sensor platform holds significant potential for the detection of a variety of medical biomarkers, including analytes related to various pathogenes, cancer biomarkers, and others.
The design of transparent conductive electrodes (TCEs) for optoelectronic devices requires a trade-off between high conductivity or transmittivity, limiting their efficiency. This paper demonstrates a novel approach to fabricating TCEs: a monolithic GaAs high contrast grating integrated with metal (metalMHCG). The technology and influence of fabricated different configurations of metalMHCG on the optical parameters will be shown. We will demonstrate above 90% absolute transmittiance of unpolarized light, resulting in 130% transmittance relative to plain GaAs substrate. Despite record high transmittance, the sheet resistance of the metalMHCG is several times lower than any other TCE, ranging from 0.5 to 1 OhmSq−1.
Monolithic subwavelength gratings integrated with metal (metalMHCG) enable nearly total transmission of light and can be fabricated with common semiconductor materials, however, they require a very high-aspect ratio between height and period of the metalMHCG stripes which is technologically challenging. This study aims the optimization of metalMHCG fabrication procedure by plasma etching taking into account the influence of process gas flow, their composition, pressure, power, and temperature on the wall shape of metaMHCG, etch rate, and etch selectivity. In the result, metalMHCG with high-aspect ratio and dimensions enabling nearly total transmission are fabricated.
We present an extensive experimental analysis of two-dimensional gallium-arsenide-based VCSEL arrays considering the impact on performance of the VCSEL density (inter-VCSEL spacing and mesa diameters), the number and arrangement of VCSEL elements, and the VCSEL vertical epitaxial design. We include computer simulations that explain well the behavior and trends we observe in our experiments. We present the most efficient modifications of the lateral and vertical VCSEL arrays designs to optimize heat dissipation, optical output power scaling, and wall plug efficiency.
Two-dimensional hexagonal VCSEL arrays with up to 37 VCSELs per array and emitting at 940 nm to 1020 nm are produced on GaAs substrates. Arrays with variable oxide aperture diameters and new processing geometries, with a focus on optimizing the tradeoffs in optical output power, bandwidth, power conversion efficiency, and emitted far field pattern for applications in optical wireless communications are characterized and compared. Standard on wafer probing and packaged array tests are performed including terrestrial free space measurements demonstrating the viability of the core VCSEL array technology for fifth, sixth, and next generation optical wireless systems.
Recently, we presented the idea of a single-element gas detector based on a VCSEL, in which the top mirror is realised as subwavelength grating (SWG). The presence of gas in the vicinity of the grating causes a change in its reflectivity, which leads to a change in the quality factor of the laser cavity. We investigate the possibility of a realisation of a single-element detector based on the SWG VCSEL, in which a Fano-resonance occurs in the SWG. We analyse the performance of such a detector based on the example of an antimonide VCSEL designed as an ethane detector.
To date, Bound States in the Continuum (BICs) with infinite quality (Q) factor have been observed in vertically symmetric photonic crystal slabs (PCS) sandwiched from top and bottom by low refractive index material. Such configurations are problematic in real life realization. Thus, we present numerical analysis of vertically nonsymmetric PCS, that exhibits BICs when specific conditions are met. We demonstrate that ~10% refractive index contrast between PCS and substrate enables BICs, which is achievable by all-semiconductor configurations. We also present Q-factor analysis of finite size semiconductor-based electrically driven devices exploiting BICs and configurations integrated with metals.
Subwavelength one-dimensional gratings (SOGs) enable high quality factor (Q) Fano resonance, which yield significant advantages for integrated photonics applications. They are realized as high refractive index membranes suspended in air, or placed on low refractive index insulators. It was not yet analyzed whether it is possible to obtain high-Q in structures where refractive index contrast between membrane and cladding is smaller than 1. With the aid of numerical simulations we demonstrate high-Q resonance occurring for refractive index contrast between membrane and cladding as small as 0.5, allowing the realization of monolithically integrated semiconductor devices.
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