Edge- and Surface-Emitting Lasers Applying TM Mode Confined at the Distributed Bragg Reflector-Air Interface

Surface-trapped electromagnetic waves can be localized at a boundary between a semiconductor distributed Bragg reflector (DBR) and the air. These waves enable a novel class of both in-plane-emitting and vertically-emitting optical devices including edge-emitting lasers, disk microlasers, near-field fiber-coupled lasers as well as vertical cavity surface emitting lasers (VCSELs). In oxide-confined VCSEL structures the surface-trapped mode can be used for engineering of coupled modes in the oxidized periphery region outside the aperture having a large overlap integral with the VCSEL modes inside the aperture region. Depending on the thickness of the distributed Bragg reflector layers, the thickness of the oxide layers and of the design of the top VCSEL cap layers, the interaction of these non-orthogonal optical modes can result in the lateral leakage of the VCSEL emission into the oxidized periphery. High order transverse VCSEL aperture modes having a higher intensity at the aperture boundary can have preference for such leakage. Mapping of the VCSEL wafers in areas with the variable aperture diameters
$D(\sim 3\ \mu \mathrm{m}\ \text{to} \sim 5\ \mu \mathrm{m})$
shows non-monotonous behavior of side mode suppression ratio (SMRS) between the fundamental and the excited mode versus
$D$
oscillating in the range from 7 dB to ∼30 dB with three clearly revealed maxima in the SMSR at particular aperture diameters. VCSELs manufactured show 40 Gb/s data transmission over 1.4 km OM5 multimode fiber without pre-emphasis or equalization.