Proton-Implanted Photonic Crystal and Holey Vertical -Cavity Surface -Emitting Lasers

81 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2007.Etched photonic crystals and wedge-shaped holes are fabricated in the top mirror of proton-implanted vertical-cavity surface-emitting laser (VCSEL) diodes to achieve single-fundamental-mode operation. A model of the effective transverse index of refraction profile for both cases is presented. The holes are etched a variety of depths for various designs to study the influence on single-mode emission. To investigate both the index confinement provided by the etched pattern and its effect on optical loss, continuous-wave and pulsed excitation experiments are performed. It is shown that proper pattern design leads to improved fundamental-mode output power, decreased threshold, and increased efficiency relative to unetched, but otherwise identical implant VCSELs. These improvements indicate a significant reduction in diffraction loss to the fundamental mode due to the index guiding provided by the etched pattern. Etching to shallow depths provides the ability to scale to large aperture sizes while etching deeply allows single-mode emission of small diameter devices. Optimized designs are then used in the fabrication of high-speed VCSELs with coplanar contacts on polyimide. The effect of photonic crystal design, and its associated improvements to loss and increased parasitic resistance, on small-signal modulation bandwidth is studied. Optimized devices exhibit a record 15-GHz small-signal modulation bandwidth.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD