In this work, an all-dielectric light polarizing element with 0 angle of incidence was fabricated and investigated. Linear polarizer for 1064 nm wavelength was formed by conformal deposition of dielectric thin films on the structured substrate. Its potential in laser applications was tested with laser-induced damage threshold evaluation for single-shot nanosecond pulses. Despite only dielectric materials, the optical resistance of the periodically structured element is several times inferior to that of the planar element. Differences in optical resistance correlate with formed electric field peaks within the modulated structure, revealing the problem to be solved in the ongoing work.
The compactization of lasers is an ongoing challenge in increasing their effectiveness and integrability of other systems, from nanosatellites to medical devices. The need to decrease their dimensions, especially, for diode-pumped solid-state microchip laser systems causes significant problems with beam quality. Such lasers feature an additional problem of Brightness to output power scaling power. We report an approach where we used a thin film dielectric Fano-like resonance structure as a replacement to a conventional output coupler to overcome this challenge. The structure is engineered to function as a flat spatial filter element for selecting the fundamental transverse mode of the cavity. We achieved an increase of 2x over a conventional setup in CW operation. The data matches well with the numerical analysis performed for a single longitudinal mode model. We predict that this discovery could lead to advanced power scaling in submillimeter cavities, while maintaining the beam quality.
This work presents the investigation of 2D periodic structures made by conformal deposition of dielectric thin films on the modulated surface, where the deposited layers repeat the primary surface. Depending on the architecture, spatial filtering and polarization control may be performed in transmission or reflection with the incidence of radiation perpendicular to the surface.
In the presentation, the overview of different technologies to form conformal coatings on periodically modulated surfaces will be presented. As the proposed 2D photonic structure can be considered a promising component for intracavity spatial filtering, the integration into a microchip laser will be presented. A significant reduction of M2 and brightness increase of two times was recorded for the microchip laser when the fabricated spatial filter was used as one of the resonator mirrors.
This study was aimed to investigate the formation of thin films on a nanostructured surface. Optical characterization revealed the presence of Fano-like resonance phenomenon in such single-layer structure, surrounded by a lower refractive index media. Also, we demonstrate a 5 µm thick photonic multilayer structure composed of alternating high- and low-index materials, providing angular selectivity of light. The proposed 2D structure can be considered as a promising component for intracavity spatial filtering even in high power microlasers. Moreover, the possibility to control polarization with such photonic structures will be presented.
This study was aimed to investigate the growth process of thin films on a pre-structured surface using different optically transparent materials and their optical properties. As results of conformal deposition of ion beam sputtered dense single layers on nano-modulated surfaces showed, replicability of surface modulation depends on the layer’s material itself. Among investigated metal oxides, namely tantalum, niobium, hafnium, and silicon oxides, materials with higher molecular weight tend to better repeatability of the initial structure. As an example, the surface modulation depth of tantalum oxide single layer of ~1 μm thickness has preserved almost 97 % of the initial structure, while the silica layer showed the most rapid smoothening of modulation since preserved only ~ 65 %. Considering that tantalum oxide single layers showed the best replicability results, its optical properties were investigated in a more detailed way. Optical characterization revealed the presence of Fano-like resonance phenomenon in such single-layer structure with high refractive index, surrounded by a lower refractive index media. Due to the coupling of thin film's waveguided modes with excited Fabry-Perot modes this phenomenon results in extremely low transmittance lines in the transmittance maps in a plane of the angle of incidence θ and wavelength λ. Moreover, these resonance lines show sensitivity to the angle and the wavelength of the incident light, which can serve as a demonstration of spatial and spectral filtering properties in such compact photonic single-layer structures.
In this study, we report Fano-like coupling of electromagnetic radiation to infinitely extended planar waveguiding modes of a spatially unbounded system, which specifically is a nanostructured thin film. Proposed design differs from conventional Fano-resonant systems, since conventional ones emerge from coupling to compact resonators with discrete spectrum. In this context, nanostructured thin films are explored by numerical simulations along with an analytical study, followed by the fabrication of the films by the ion beam sputtering method on nano-modulated substrates. Experimental results showed Fano-like resonances of high sensitivity to wavelength and incidence angle of the radiation. Hence, proposed design can be a potential candidate for frequency- and spatial filtering of light in transmission/reflection through/from such nanostructured thin films.
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