Abstract: A vertical-cavity surface-emitting laser (VCSEL) is provided that includes a mesa structure disposed on a substrate. The mesa structure defines an emission axis of the VCSEL. The mesa structure includes a first reflector, a second reflector, and a cascaded active region structure disposed between the first reflector and the second reflector. The cascaded active region structure includes a plurality of cascaded active region layers disposed along the emission axis, where each of the cascade active region layers includes an active region having multi-quantum well and/or dots layers (MQLs), a tunnel junction aligned with the emission axis, and an oxide confinement layer. The oxide confinement layer is disposed between the tunnel junction and MQLs, and has an electrical current aperture defined therein. The mesa structure defines an optical window through which the VCSEL is configured to emit light.

Abstract: Several VCSEL devices for long wavelength applications in wavelength range of 1200-1600 nm are described. These devices include an active region between a semiconductor DBR on a GaAs wafer and a dielectric DBR regrown on the active region. The active region includes multi-quantum layers (MQLs) confined between the active n-InP and p-InAlAs layers and a tunnel junction layer above the MQLs. The semiconductor DBR is fused to the bottom of the active region by a wafer bonding process. The design simplifies integrating the reflectors and the active region stack by having only one wafer bonding followed by regrowth of the other layers including the dielectric DBR. An air gap is fabricated either in an n-InP layer of the active region or in an air gap spacer layer on top of the semiconductor DBR. The air gap enhances optical confinement of the VCSEL. The air gap may also contain a grating.