Near-UV Gan VCSELs Enabled by Nanoporous Optical Engineering
Abstract
In response to the need of chip-scale atomic clocks based on Yb ions, we propose the development of a compact GaN-based vertical cavity surface-emitting laser (VCSEL) that will emit at 369.1nm with hop-free mode stability and a narrow spectral linewidth. At present the pumping of a Yb-ion transition in an atomic clock is enabled with a frequency-doubled, external-cavity laser that cannot be easily miniaturized. The wavelength of commercial solid-state diode laser is unfortunately limited to above 370 nm; these diode lasers are of the type of edge-emitting laser with a high power consumption (~0.5 W), multiple longitudinal modes, and a narrow free spectral range (FSR, .f < 70 GHz), consequently unsuitable as an effective source for pumping atomic transitions. The goal of this proposal is to develop a compact, low power, coherent, and single mode light source operated in the near-ultraviolet (~369 nm) spectral range. Such a compact and single mode source has not been realized but is expected to have broad applications in information processing, micro-display and projection, high-resolution printing, biophotonics, spectroscopic probing, and atomic optics, to name just a few. Vertical cavity surface emitting laser (VCSEL) is the most promising candidate for such a coherent light source. Wide bandgap AlGaInN semiconductor family has a direct bandgap that suitably covers this wavelength. In spite of a few reports of InGaN VCSELs in the blue and green, the processes of fabricating these microcavities have been exceedingly complicated, causing a severe downgrade in device performance (relative to other commercial III-nitride emitters). Furthermore, the processes described do not offer sufficient controllability and reproducibility. The purpose of this proposal is to investigate a new process in fabricating InGaN VCSELs using a special nanoporous GaN (NP-GaN) capable of circumventing these daunting challenges. Using such a NP-GaN, we have new freedom in optical engineering of microcavity design without the complex constraints in epitaxy or fabrication. More importantly, the NP GaN-based reflector will give the III-nitride material system, for the first time, a design option of a conductive mirror to support vertical current injection that is crucially vital in attaining high performance VCSELs.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 12, 2017
- Source ID
- W911NF1510378
Entities
People
- Jung Han
Organizations
- Army Contracting Command
- Office of the Secretary of Defense
- Yale University