Vertical cavity surface emitting laser

[shanker]

The vertical-cavity surface-emitting laser (VCSEL) is a type of semiconductor laser diode with laser beam emission perpendicular from the top surface, contrary to conventional edge-emitting semiconductor lasers (also in-plane lasers) which emit from surfaces formed by cleaving the individual chip out of a wafer.There are several advantages to producing VCSELs when compared with the production process of edge-emitting lasers. Edge-emitters cannot be tested until the end of the production process. If the edge-emitter does not work, whether due to bad contacts or poor material growth quality, the production time and the processing materials have been wasted. VCSELs can be tested at several stages throughout the process to check for material quality and processing issues. For instance, if the vias have not been completely cleared of dielectric material during the etch, an interim testing process will flag that the top metal layer is not making contact to the initial metal layer. because VCSELs emit the beam perpendicular to the active region of the laser as opposed to parallel as with an edge emitter, tens of thousands of VCSELs can be processed simultaneously on a three inch Gallium Arsenide wafer. even though the VCSEL production process is more labor and material intensive, the yield can be controlled to a more predictable outcome.

[gyanasagar]

In an information society, where the primary preoccupation in life is the generation, dissemination and management of information, there is an ever-increasing appetite for computing power and interconnection bandwidth. In the coming era of teraflop computing and multi terabyte storage, multiple processors and large data stores will be interconnected with up to terabit per second aggregate bandwidth over distance extending from just centimeters to hundreds of meters. VCSEL based optical interconnections can meet the speed, distance and density demands at affordable costs. Free space links based on arrays of VCSELs may provide just the high density two dimensional interconnects needed to relieve current processor I/O bottle necks and pave the way to massively parallel tereflop processors. We will take a closer look at VCSEL and conventional sources like edge emitting lasers and LED s to see why VCSEL s are generating so much excitement.