Oxide-confined quantum-well microcavity vertical-cavity surface-emitting lasers (VCSELs) of three-diameters (aperture size dA ∼2, 2.5, and 3.5 μm) have been fabricated that operate as nearly single-mode lasers at ultralow thresholds ITH =0.15, 0.16, and 0.20 mA. Relative spectral intensities are measured at a set higher bias current I=0.8 mA for the three VCSEL sizes to determine the dependence on mode spacing between the fundamental and second order modes, which at increasing diameter are Δ λ∼2.2, 1.6, and 1.0 nm. By studying the side-mode suppression ratio and the optical microwave frequency response of the microcavity VCSELs throughout a spread-out group of modes, we are able to resolve the dependence of signal amplitude and time response on the difference in mode spacing, Δ λ, higher speed response occurring at larger Δ λ.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)