Mode control using transversal bandgap structure in vcsels

Abstract

A vertical cavity surface emitting laser (VCSEL) having a photonic band gap (PBG) region formed within or adjacent to a first and/or a second mirror, or within a spacer layer positioned between a gain region and at least one of the mirrors. The PBG region has a predetermined periodicity which substantially prevents the generated light from propagating the region, and defines a light aperture without the periodicity so as to allow the generated light to propagate through the aperture. The PBG region does not extend through the gain region, thereby allowing the full gain region to be used. Controls the efficiency of laser action by suppressing or preventing laser action in certain modes without losses, rather the modes are made forbidden. Energy from the forbidden modes is eventually coupled back to the allowed mode(s). Provides a separation of the confinement of the gain region and the mode control without introducing energy losses.