K. M. Geib

Comparison of wavelength splitting for selectively oxidized, ion implanted, and hybrid vertical-cavity surface-emitting lasers

The wavelength splitting between the LP/sub 01/ and LP/sub 11/ modes of selectively oxidized, ion implanted, and hybrid ion implanted/selectively oxidized vertical-cavity surface-emitting lasers is studied by experiment and theory. Measured splittings at threshold show marked differences between the different laser structures due to the effects of index guiding and thermal lensing. Theoretical results were obtained using a vector optical mode solver and show good agreement with experimental results. The hybrid lasers exhibited behavior intermediate between the ion implanted and selectively oxidized lasers and could be optimized for high power single transverse mode emission.

Transverse mode measurements in index guided vertical cavity semiconductor lasers

Summary form only given. Vertical cavity surface-emitting semiconductor lasers (VCSELs) have many applications in information technology, particularly communications and data storage. These applications require careful control of their emission spectra, transverse modes and polarisation properties. Index-guided VCSELs using oxide confinement are particularly promising due to their generally low lasing thresholds, high efficiencies and excellent electrical properties. However, there have been no systematic studies of their transverse mode properties. In this paper we describe recent measurements of transverse modes in oxide confined AlGaAs VCSELs of aperture sizes ranging from 1 to 20 /spl mu/m square.

Advanced Concepts for High-Power VCSELS and 2-Dimensional VCSEL Arrays

We have developed high power vertical cavity surface emitting lasers (VCSELS) for multimode or single mode operation. We have characterized new cavity designs for individual lasers and 2-dimensional VCSEL arrays to maximize output power. Using broad area high power VCSELS under pulsed excitation, we have demonstrated the triggering of a photoconductive semiconductor switch (PCSS) with a VCSEL. We also have developed designs for high output power in a single mode. The first approach is to engineer the oxide aperture profile to influence the optical confinement and thus modal properties. A second approach focuses on leaky-mode concepts using lateral modification of the cavity resonance to provide the lateral refractive index difference. To this end, we have developed a regrowth process to fabricate single-mode VCSELS. The overall objective of this work was to develop high-power single-mode or multimode sources appropriate for many applications leveraging the many inherent advantages of VCSELS.

Size dependence of selectively oxidized VCSEL transverse-mode structure

We report the spectral and modal properties of small (0.5- to 5-/spl mu/m current aperture) VCSELs and identify Joule heating as a dominant effect in the resonator properties of the smallest lasers. The lasers studied here were AlGaAs structures with semiconductor distributed Bragg reflectors (DBRs), where the selectively oxidized confinement layer is pulled back three mirror periods from each side of the active region to produce a lateral effective index difference of 0.05.

The technology and applications of selective oxidation of AlGaAs

Wet oxidation of AlGaAs alloys, pioneered at the University of Illinois a decade ago, recently has been used to fabricate high performance vertical-cavity surface emitting lasers (VCSELs). The superior properties of oxide-confined VCSELs has stimulated interest in understanding the fundamentals of wet oxidation. We briefly review the technology of selective oxidation of III-V alloys, including the oxide microstructure and oxidation processing as well as describe its application to selectively oxidized VCSELs.

Engineering the optical properties of selectively oxidized vertical cavity lasers

control of the absorber voltage bias will lead to high frequency modulation. As our experiments demonstrate, variation of the voltage on the absorber region within the VCSEL mirror stack proves to be an effective optical modulation technique. We anticipate better frequency chirping characteristics, lower ac drive power, and better modulation efficiency as compared with direct current modulation.