Dual Etching Research Articles

High-performance ultra-compact polarization splitter-rotators based on dual-etching and tapered asymmetrical directional coupler

High-performance ultra-compact polarization splitter-rotators (PSRs) are designed and experimentally demonstrated, using dual etching and a tapered asymmetrical directional coupler. First, two novel PSRs are designed with nanowire and subwavelength grating cross-port waveguides and verified in simulations. Then, one of the two PSRs is fabricated. Experiment results reveal that the extinction ratio is higher than 28 dB or 32 dB at 1550 nm for the launched fundamental transverse magnetic or the transverse electric modes, while the corresponding insertion loss and polarization conversion loss are 0.33 dB and 0.18 dB, respectively.

Interface Between MTA and Dental Bonding Agents: Scanning Electron Microscope Evaluation.

Aims and Objectives:Nowadays, the material that offers the best sealing characteristic in the field of endodontic treatment is the mineral trioxide aggregate (MTA), nevertheless, this material necessities an adhesive bonding agent to perfectly join to the dental surface. The aim of this study was to analyze using a scanning electron microscope (SEM) the possible microgap between the adhesive, MTA, and the dental surface.Material and Methods:Fourteen extracted molars were divided into two groups – group A was prepared with MTA-component adhesive and group B was prepared with MTA and composite dual etching. The observations were carried out with a SEM Phenom G2 Pro mode S.E.I. JMP® software was used for statistical analysis, and a t-test was used for evaluating the difference between the two groups.Results:The gap of the areas at higher magnification (1000×) with a size greater than 5 microns in width and 20 microns in length were considered significant, and only group A recorded significant data.Conclusions:The SEM analysis performed in the group A with interposition of adhesive and flow between the dental pulp chamber and MTA demonstrates the presence of a marginal gap of considerable amplitude in the all of the samples investigated.

Enhanced Light Extraction from GaN-Based Vertical Light-Emitting Diodes with a Nano-Roughened <I>N</I>-GaN Surface Using Dual-Etch

The effect of the dual-etch surface roughening method consisting of dry etching and wet etching on the enhancement of light extraction of vertical light emitting diodes (VLEDs) is investigated. The surface of a VLED was roughened by dry etching using SiO2 spheres as the mask while a KOH solution was used for wet etching. After the surface of the VLED was roughened by the dual-etch method, the luminous efficiency of the VLED increased due to the formation of uniform, nano-scale cone shapes and the decreased flat area ratio of the total GaN surface. The VLED roughened by dual etching showed about 9.3% higher emitted luminous efficiency than the VLED roughened using wet etching.