14 July 2000 Optical physics of VCSEL tapered oxide apertures
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Proceedings Volume 3944, Physics and Simulation of Optoelectronic Devices VIII; (2000) https://doi.org/10.1117/12.391427
Event: Symposium on Integrated Optoelectronics, 2000, San Jose, CA, United States
We present a theoretical analysis of the optical physics of tapered oxide apertures in long- and short-cavity VCSELs. We apply our quasi-exact vector finite element model to a USC (long cavity) and U. Texas (short cavity) VCSEL to compute the electric field distribution, transverse confinement factor, diffraction rate, and threshold gain of the fundamental lasing mode. Making qualitative reference to the Hegblom, et al model, we analyze our results to deduce the fundamental physical effects of the tapered oxide aperture. We find that tapered oxides reduce diffraction loss through two separate physical phenomena: (1) a reduction in transverse confinement yielding a flatter phase front, and (2) an effective lens which acts to refocus the naturally diffracting wave front. We further find that in most VCSELs an inherent trade-off exists between minimizing the diffraction loss and maximizing the optical mode-to-gain interaction. To achieve the ultimate goal of (near) thresholdless lasing, this trade-off must be overcome: diffraction loss must be eliminated while simultaneously minimizing the mode volume. We conclude with a suggestion for a novel cavity design, which in theory achieves this goal.
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Michael J. Noble, Michael J. Noble, Paul Sotirelis, Paul Sotirelis, James A. Lott, James A. Lott, John P. Loehr, John P. Loehr, "Optical physics of VCSEL tapered oxide apertures", Proc. SPIE 3944, Physics and Simulation of Optoelectronic Devices VIII, (14 July 2000); doi: 10.1117/12.391427; https://doi.org/10.1117/12.391427

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