Fabrication and characterization of integrable GaAs-based high-contrast grating reflector and Fabry-Pérot filter array with GaInP sacrificial layer

Integrable GaAs-based high-contrast gratings (HCGs) are fabricated and characterized, targeting applications in high-speed vertical-cavity surface-emitting lasers (VCSELs). A Ga 0.51 In 0.49 P sacrificial layer beneath the GaAs layer is employed to create a low index surrounding HCG strips by selective etching. Experimental results show that the finite-size HCG has a reflectivity of 93% from 1270 to 1330 nm for the transverse magnetic polarization, which is consistent with the calculated results. An HCG-based Fabry-Perot filter array formed by the different HCGs, air gap, and GaAs substrate is demonstrated. The measured resonance wavelengths of the filter arrays are consistent with the theoretical results, which implies that the resonance wavelength of such filters can be tuned by parameters of the HCG itself

GaAs-based subwavelength grating on an AlOx layer for a vertical-cavity surface-emitting laser

© 2020 Optical Society of America. Users may use, reuse, and build upon the article, or use the article for text or data mining, so long as such uses are for non-commercial purposes and appropriate attribution is maintained. All other rights are reserved.A GaAs-based subwavelength grating on a thick (∼3/4*λ at 1300 nm) AlOx layer is designed, fabricated, and characterized. The AlOx layer as a low-index medium is oxidized from a 640-nm Al0.9Ga0.1As layer. The layer contraction of the Al0.9Ga0.1As layer after wet oxidation to AlOx is 4.9%. We fabricated GaAs-based subwavelength gratings on the AlOx layer showing a high reflectivity of 90% in the 1300-nm wavelength range, consistent with the simulation results. Such GaAs-based subwavelength gratings can be used as high-contrast grating mirrors for narrow-linewidth VCSELs, improving the mechanical stability and simplifying the device fabrication

The Development of a Site Plan and Flatwork Design for Good Rest Orphanage

Good Rest Orphanage, located in Croix Des Bouquets, Haiti, has been supported by Children’s Heritage Foundation (CHF) for over 15 years and was in need of basic site plans and a flatwork design. Proper in field data was collected on a trip to Haiti during the summer of 2019. This material was then assembled in AutoCAD to create six pages of detailed drawings. A flatwork, or sidewalk system was then designed in AutoCAD based off the assembled model. Next an estimate for the cost to construct the sidewalks was developed and refined in excel. Various obstacles were overcome in the process of developing these drawings and estimate from a lack of proper surveying equipment to missing in-field information. The estimate will provide CHF with the necessary information to bid and install a proper flatwork system at Good Rest Orphanage which will increase its resident’s quality of life. These drawings will now be used in all reconstruction and new construction efforts for the future of Good Rest Orphanage

Thermal analysis of high-bandwidth and energy-efficient 980 nm VCSELs with optimized quantum well gain peak-to-cavity resonance wavelength offset

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Appl. Phys. Lett. 111, 243508 (2017) and may be found at https://doi.org/10.1063/1.5003288.The static and dynamic performance of vertical-cavity surface-emitting lasers (VCSELs) used as light-sources for optical interconnects is highly influenced by temperature. We study the effect of temperature on the performance of high-speed energy-efficient 980 nm VCSELs with a peak wavelength of the quantum well offset to the wavelength of the fundamental longitudinal device cavity mode so that they are aligned at around 60 °C. A simple method to obtain the thermal resistance of the VCSELs as a function of ambient temperature is described, allowing us to extract the active region temperature and the temperature dependence of the dynamic and static parameters. At low bias currents, we can see an increase of the −3 dB modulation bandwidth f−3dB with increasing active region temperature, which is different from the classically known situation. From the detailed analysis of f−3dB versus the active region temperature, we obtain a better understanding of the thermal limitations of VCSELs, giving a basis for next generation device designs with improved temperature stability

Protein-DNA force assay in a microfluidic format

The detailed study of protein-DNA interactions is a core effort to elucidate physiological processes, including gene regulation, DNA repair and the immune response. The molecular force assay (MFA) is an established method to study DNA-binding proteins. In particular, high-affinity binder dissociation is made possible by the application of force. Microfluidic lab-on-a-chip approaches have proven helpful for parallelization, small sample volumes, reproducibility, and low cost. We report the successful combination of these two principles, forming a microfluidic molecular force assay and representing a novel use for the established MITOMI chip design. We present, characterize, validate and apply this integrated method. An alternative confocal fluorescence microscopy readout and analysis method is introduced and validated. In a multiplexing application, EcoRI binding is detected and characterized. This method paves the way for quantitative on-chip force measurements. It is suited for integration with DNA micro-spotting and in vitro expression of transcription factors to form a high-throughput chip for detailed DNA-protein interaction studies