Tunable VCSEL

Vertical-cavity surface emitting lasers (VCSELs) are now key optical source s in optical communications, Their main application is currently in local a rea networks using multimode optical fibers. VCSELs are also being rapidly commercialized for single-mode fiber metropolitan area and nide area networ k applications, The advantages of VCSEL include simpler fiber coupling, eas ier packaging and testing, and the ability to be fabricated in arrays. In a ddition, VCSELs have an inherent single-wavelength structure that is well s uited for wavelength engineering. All these advantages promise to lead to c ost-effective wavelength-tunable lasers, which are essential for the future intelligent, all-optical networks. In this paper, I will review the advances on wavelength-tunable VCSELs. I w ill summarize some of the early breakthroughs in wavelength engineering of VCSELs and then concentrate on the designs and properties of micromechanica l tunable VCSEL.