Sponsor: National Science Foundation

Title: Gain and Recombination in InGaAsN and Their Impact on the Laser Output Behavior

Investigator(s): C.S. Menoni

Abstract
The scientific objective of the proposed research is to investigate the dominant recombination processes and the mechanisms that give rise to optical gain in InGaAsN/GaAs heterostructures lasers, and determine their impact on the laser output behavior. To accomplish this, the PI's will perform a comprehensive set of experiments on optimized ridge waveguide structures that include carrier lifetime, gain, gain recovery dynamics, and spontaneous emission measurement at different bias and temperature conditions. They will complement these investigations with optical spectroscopic studies of the heterostructure materials that will reveal the salient features of the electronic structure modifications upon nitrogen incorporation. The results from these experiments will allow us to build a model of the gain, determine the carrier-current density relations and thus develop a thorough understanding of the role of gain and recombination in affecting the threshold current and external efficiency of dilute nitride lasers. To complete these studies we also propose to assess the high speed potential of dilute nitride lasers through investigations of the intrinsic modulation bandwidth.

This research brings together the CSU group whose strength is in the characterization of laser diodes and their heterostructures, and the Sandia's groups specialists in the growth of III-V nitrides and modeling of fundamental laser diode behavior respectively. The synergy of these groups with complementary expertise, will create an exciting intellectual exchange that will greatly benefit the education of the graduate and undergraduate students participating in the project.

The proposed research will offer outstanding opportunities for the training of students at all levels. Graduate students will learn the arts of device fabrication, and characterization using high frequency electronics, optics and ultrafast techniques. They will also acquire in-depth understanding of the material's optical and electronic properties and develop skills to simulate basic laser diode behavior. Furthermore, the research will offer unique opportunities for the development of leadership skills through participation in conference presentations, manuscript preparation and mentoring activities. Exciting learning opportunities will also be available for undergraduate students who will take part in device fabrication efforts and in performing some of the simpler device and material characterization experiments. In undergraduate recruitment, Prof. Menoni will actively collaborate with the Louis Stokes Alliance for Minority Participation (COAMP) and the College of Engineering Women and Minorities Organization to attract talented students from traditionally underrepresented minority groups in the science and engineering. Basic research in laser diodes will also open up learning opportunities for K-12 students, who will be recruited from local high schools to participate in a month-long summer research experiences.