Vertically emitting annular Bragg lasers using polymer epitaxial transfer

Fabrication of a planar semiconductor microcavity, composed of cylindrical Bragg reflectors surrounding a radial defect, is demonstrated. A versatile polymer bonding process is used to transfer active InGaAsP resonators to a low-index transfer substrate. Vertical emission of in-plane modes lasing at telecom wavelengths is observed under pulsed optical excitation with a submilliwatt threshold

Technique for producing wind-tunnel heat-transfer models

Inexpensive thin skinned wind tunnel models with thermocouples on certain surface areas were fabricated. Thermocouples were designed for measuring aerodynamic heat transfer in wind tunnels

Electrically pumped two-dimensional Bragg grating lasers

We demonstrate electrically pumped InGaAsP two-dimensional Bragg grating (2DBG) lasers with two line defects. The 2DBG structure uses a weak 2D index perturbation surface grating to control the optical modes in the plane of the wafer. Measurements of the 2DBG lasers show that modal control in both the longitudinal and transverse directions is due to the gratings and defects. The 2DBG lasers are promising candidates for single-mode, high power, and high efficiency large-area lasers

Assessment of lithographic process variation effects in InGaAsP annular Bragg resonator lasers

Optical microresonators based on an annular geometry of radial Bragg reflectors have been designed and fabricated by electron-beam lithography, reactive ion etching, and an epitaxial transfer process. Unlike conventional ring resonators that are based on total internal reflection of light, the annular structure described here is designed to support optical modes with very small azimuthal propagation coefficient and correspondingly large free spectral range. The effect of lithographic process variation upon device performance is studied. Laser emission wavelength and threshold optical pump power are found to vary between similar devices given different electron doses during electron-beam lithography. As the resonance wavelength and quality factor of these resonators are very sensitive to environmental changes, these resonators make ideal active light sources that can be integrated into large arrays for gas and liquid sensing applications and are easily interrogated

Leadership judgment: Without it nothing else matters

No abstract.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/58085/1/277_ftp.pd

Process Evaluation of a Peer-Driven, HIV Stigma Reduction and HIV Testing Intervention in Latino and African American Churches.

Purpose: Faith-based organizations may be effective in addressing HIV-related disparities, but few interventions have been implemented across diverse churches. The Facilitating Awareness to Increase Testing for HIV (FAITH) intervention harnessed peer leadership to decrease HIV stigma and promote HIV testing in African American and Latino congregations. A pilot study found more consistent effects among Latino congregations. This process evaluation evaluates implementation of FAITH to better understand the pilot study's findings. Methods: Data sources included HIV education and peer leader workshop evaluation forms, participant views of the community's perspective of HIV, and peer leader follow-up interviews. Data were triangulated with systematic observation notes and analyzed using process-related themes of recruitment, reach, context, implementation, dose-delivered, and fidelity. Results: At the Latino churches (compared to the African American church), facilitators spent more time addressing community-based misconceptions about HIV. The peer leader model was well received, especially among Latino participants, and most said that after the workshop they felt comfortable speaking with others about HIV-related topics. Latino peer leaders reported speaking with up to 20 people within their social networks (particularly with family members); African Americans reported up to 4. Implementation challenges at the African American church may have contributed to the limited intervention effects. Nevertheless, we found the peer motivator model feasible and acceptable across diverse faith settings. Conclusion: Peer-based models within faith settings are promising for addressing HIV. However, differences among groups in HIV knowledge, social network characteristics and norms, and church preferences may influence overall effectiveness

Hybrid InGaAsP-InP Mach-Zehnder racetrack resonator for thermooptic switching and coupling control

An InGaAsP-InP optical switch geometry based on electrical control of waveguide-resonator coupling is demonstrated. Thermooptic tuning of a Mach-Zehnder interferometer integrated with a racetrack resonator is shown to result in switching with ON-OFF contrast up to 18.5 dB. The optical characteristics of this unique design enable a substantial reduction of the switching power, to a value of 26 mW in comparison with 40 mW for a conventional Mach-Zehnder interferometer switch. Modulation response measurements reveal a 3 dB bandwidth of 400 kHz and a rise time of 1.8 µs, comparing favorably with current state-of-the-art thermooptic switches

The 1988 Solid Waste Management Act -- Facing Up to the Garbage Component of Florida\u27s Burgeoning Growth

Due in part to the high rate of population growth in Florida and the increasing rates of solid waste generation by Floridians, the problem of solid waste management has generated serious statewide concern. In an effort to address this critical environmental issue, the Florida Legislature during the 1988 Regular Session passed the Solid Waste Management Act. In this Article, Mr. Preston and Mr. DeRose outline the development of this significant new legislation, summarize its main provisions, and highlight the Act\u27s funding sources as well as the new regulatory and rulemaking activities that will be undertaken to implement the Act

Active coupled-resonator optical waveguides. II. Current injection InP-InGaAsP Fabry-Perot resonator arrays

We investigate active, electrically pumped coupled-resonator optical waveguides (CROWs) in the form of InP-InGaAsP Fabry-Perot resonator arrays. We discuss the fabrication of these devices and present measurements of the transmission spectra. The signal-to-noise ratio is found to be a strong function of wavelength and degraded rapidly along the resonator chain away from the input. Our results highlight a number of ingredients toward practical implementations loss-compensated and amplifying CROWs

Two-dimensional Bragg grating lasers defined by electron-beam lithography

Two-dimensional Bragg grating (2DBG) lasers with two quarter-wave slip line defects have been designed and fabricated by electron-beam lithography and reactive ion etching. Unlike conventional two-dimensional photonic crystal defect lasers, which use a large refractive index perturbation to confine light in a plane, the 2DBG structures described here selectively control the longitudinal and transverse wave vector components using a weak index perturbation. Two line defects perpendicular to each other are introduced in the 2DBG to define the optical resonance condition in the longitudinal and transverse directions. In this article, we describe the lithography process used to pattern these devices. The 2DBG lasers were defined using polymethylmethacrylate resist exposed in a Leica Microsystems EBPG 5000+ electron-beam writer at 100 kV. A proximity correction code was used to obtain a uniform pattern distribution over a large area, and a dosage matrix was used to optimize the laser design parameters. Measurements of electrically pumped 2DBG lasers showed modal selection in both the longitudinal and transverse directions due to proper design of the grating and defects, making them promising candidates for single-mode, high power, high efficiency, large-area lasers