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Vertical Bragg grating mirrors are realized by the anisotropic etching of Si using deep reactive ion etching (DRIE), thus producing multiple vertical interfaces between Si and air. The Bragg mirrors are used to realize two optical filter configurations. The first is a tunable Fabry–Pérot cavity composed of two mirrors, where tuning is achieved by moving one of the mirrors using silicon-on-insulator (SOI) electrostatic microelectromechanical system (MEMS) actuation. The second is a drop filter, where a tilted Bragg mirror acts as a wavelength selective reflector. The enhanced etching process involving a mix of cryogenic and Bosch DRIE processes is presented. The realized structures, fabrication process, as well as measured performance are also presented. [ABSTRACT FROM PUBLISHER]

In this work, we study the effect of shutter thickness on the optical attenuation of an opto-mechanical variable optical attenuator (VOA). Both experimental and simulation results show maximum shutter displacement in the received optical field, which increases with larger shutter thickness. This behaviour has not been reported or analysed previously. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 110–112, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10690 [ABSTRACT FROM AUTHOR]

Mid-infrared Fourier-transform infrared (FT-IR) spectroscopy of liquid biological samples is limited by the high absorption of water in this spectral range, which makes conventional transmission cuvettes unsuitable as their centimeter-scale length is already too big. The most common alternative relies on the use of attenuated total reflection (ATR) accessories, which provide a small interaction path length for light along the interface between the analyte and the expensive ATR crystals. In this work, we address this issue by proposing a disposable and low-cost micro-transmission cell. Its construction relies on a simple technique, which consists of dispersing plastic spherical microparticles in a liquid sample before dispensing it between two pieces of silicon assembled one onto the other and acting as windows for the cell. Consequently, the microparticles act as a spacer of very precise height in-between the two silicon windows. This technique allows easy construction of infrared absorption cells with near-optimum optical interaction path length just by selecting the most appropriate particle size. The concept is demonstrated by measuring the concentration of glucose in aqueous solutions using microspheres of diameter 20 μm then 40 μm and analyzing the corresponding glucose absorption peaks in the wavenumber range 950-1200 cm -1 . The performance is compared to that of standard ATR spectroscopy of the same samples. This resulted in a root-mean-square error of cross-validation (RMSECV) of 58.8 mg dl -1 as obtained for transmission measurements by partial least squares (PLS) regression, which is comparable to the RMSECV of 53 mg dl -1 for single-reflection diamond ATR measurements.

The present study designed to evaluate the healing power of platelet-rich fibrin (PRF) in terms of pain control and mucosal repair. A randomised, controlled, pilot clinical trial was conducted on 16 patients randomly distributed with 1:1 allocation ratio into two groups. The treatment group received PRF minced and mixed with orabase and the control group received clobetasol propionate 0.05% mixed with orabase. Pain reduction was evaluated as primary outcome along with mucositis healing as secondary outcome. A statistically significant difference in pain reduction was observed between the two groups (p ≤ 0.05). The clinical results at Day 7 has shown that PRF group had 100% pain reduction while, CP group had 32.5% reduction from base line. PRF offered superior clinical results providing rapid pain alleviation and accelerated ulcer healing compared to corticosteroids., (© 2022 The Wound Healing Society.)

A wide angle microscanning architecture is presented in which the angular deflection is achieved by displacing the principle axis of a curved silicon micromirror of acylindrical shape, with respect to the incident beam optical axis. The micromirror curvature is designed to overcome the possible deformation of the scanned beam spot size during scanning. In the presented architecture, the optical axis of the beam lays in-plane with respect to the substrate opening the door for a completely integrated and self-aligned miniaturized scanner. A micro-optical bench scanning device, based on translating a 200 μm focal length micromirror by an electrostatic comb-drive actuator, is implemented on a silicon chip. The microelectromechanical system has a resonance frequency of 329 Hz and a quality factor of 22. A single-mode optical fiber is used as the optical source and inserted into a micromachined groove fabricated and lithographically aligned with the microbench. Optical deflection angles up to 110 degrees are demonstrated.