We report on progress in the realization of Field Emission Devices (FED) with AlN-based anodes emitting in the spectral window of 200-230nm for persistent disinfection of air and surfaces in the presence of humans. Modeling, experimental studies, and trade-offs between sputter deposition and MOVPE grown AlN anode films and GaN/AlN multiple quantum wells (MQW) indicate the feasibility of 1’’-size FED emitting at 225 nm wavelength with 1 mW power, capable to quickly deactivate the SARS-CoV-2 virus.
We have designed, fabricated and tested narrow-band Fabry-Perot filters in the infrared using gold porous mirrors and a silicon spacer layer. The filter peaks at 10 μm and 15 μm have approximately 10% transmission and a 1.5% linewidth. A Fabry-Perot structure with plane metal layers having a similar linewidth would have a transmission of only 0.2%. Thus, for the same linewidth we have improved the transmission by a factor of 50. Apart from the optical enhancements, these filters also have the advantage that they can be made inexpensively in a standard silicon MEMS technology and that their resonances can be finely tuned through post processing.
The interest in MEMS based Micro-Spectrometers is increasing due to their potential in terms of flexibility as well as cost, low mass, small volume and power savings.
This interest, especially in the Near-Infrared and Mid- Infrared, ranges from planetary exploration missions to astronomy, e.g. the search for extra solar planets, as well as to many other terrestrial fields of application such as, industrial quality and surface control, chemical analysis of soil and water, detection of chemical pollutants, exhausted gas analysis, food quality control, process control in pharmaceuticals, to name a few. A compact MEMS-based Spectrometer for Near- Infrared and Mid-InfraRed operation have been conceived, designed and demonstrated. The design based on tunable MEMS blazed grating, developed in the past at CSEM [1], achieves state of the art results in terms of spectral resolution, operational wavelength range, light throughput, overall dimensions, and power consumption.
Diffractive MEMS are interesting for a wide range of applications, including displays, scanners or switching elements. Their advantages are compactness, potentially high actuation speed and in the ability to deflect light at large angles.
We have designed and fabricated deformable diffractive MEMS grating to be used as tuning elements for external cavity lasers. The resulting device is compact, has wide tunability and a high operating speed.
The initial design is a planar grating where the beams are free-standing and attached to each other using leaf springs. Actuation is achieved through two electrostatic comb drives at either end of the grating. To prevent deformation of the free-standing grating, the device is 10 μm thick made from a Silicon on Insulator (SOI) wafer in a single mask process.
At 100V a periodicity tuning of 3% has been measured. The first resonant mode of the grating is measured at 13.8 kHz, allowing high speed actuation. This combination of wide tunability and high operating speed represents state of the art in the domain of tunable MEMS filters.
In order to improve diffraction efficiency and to expand the usable wavelength range, a blazed version of the deformable MEMS grating has been designed. A key issue is maintaining the mechanical properties of the original device while providing optically smooth blazed beams. Using a process based on anisotropic KOH etching, blazed gratings have been obtained and preliminary characterization is promising.
The EUSO (Extreme Universe Space Observatory) project is developing a new mission concept for the scientific
research of Ultra High Energy Cosmic Rays (UHECRs) from space. The EUSO wide-field telescope will look down
from space onto the Earth night sky to detect UV photons emitted from air showers generated by UHECRs in our
atmosphere. In this article we concentrate on the mitigation strategies agreed so far, and in particular on the
implementation of a careful early selection and testing of subsystem materials (including optics), design and interfaces of
the subsystem and an optimization of the instrument operational concept.
Diffractive MEMS are interesting for a wide range of applications, including displays, scanners or switching elements. Their advantages are compactness, potentially high actuation speed and in the ability to deflect light at large angles.
We have designed and fabricated deformable diffractive MEMS grating to be used as tuning elements for external cavity lasers. The resulting device is compact, has wide tunability and a high operating speed.
The initial design is a planar grating where the beams are free-standing and attached to each other using leaf springs. Actuation is achieved through two electrostatic comb drives at either end of the grating. To prevent deformation of the free-standing grating, the device is 10 μm thick made from a Silicon on Insulator (SOI) wafer in a single mask process.
At 100V a periodicity tuning of 3% has been measured. The first resonant mode of the grating is measured at 13.8 kHz, allowing high speed actuation. This combination of wide tunability and high operating speed represents state of the art in the domain of tunable MEMS filters.
In order to improve diffraction efficiency and to expand the usable wavelength range, a blazed version of the deformable MEMS grating has been designed. A key issue is maintaining the mechanical properties of the original device while providing optically smooth blazed beams. Using a process based on anisotropic KOH etching, blazed gratings have been obtained and preliminary characterization is promising.
Silicon has been widely used as the material of choice for the fabrication of MEMS I MST devices. The compatibility of MEMS manufacturing equipment with standard IC equipment presents one ofthe main reasons for this choice. However, over the past years, we have seen new equipment dedicated to MEMS fabrication enter the market place. One such example is the Deep Reactive Ion Etcher, which is capable of vertically etching silicon at a rate of several microns per minute. This type of equipment, now available from several vendors, has revolutionized the MEMS fabrication capabilities and has opened the door to a whole new family of MEMS devices [1].
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