Single‐Mode VCSELs for Sensing Applications

This chapter describes single‐mode vertical cavity surface emitting lasers (VCSELs) and their applications in several sensors. Semiconductor lasers oscillate in different modes that depend on the dimensions of the optical resonator. The chapter focuses on true single‐mode lasers, meaning operation in a single polarization and single spectral mode. The ability to adjust the wavelength of a laser, particularly of single‐mode lasers, is very attractive in many applications. Many of the applications for single‐mode‐VCSELs have a unique requirement that forces the users to a single‐mode device. One of the most ubiquitous applications of lasers is in printing, where nearly every office and many homes have at least one laser printer. Gas sensors work by tuning a laser to the atomic absorption spectrum of the subject molecule. Atomic clocks are used to create timing standards in telecommunications systems and for precise synchronous detection of events such as in oil field exploration.