VCSELs, contrary to convention

SUSAN PETRIE, SENIOR EDITOR, susan.petrie@photonics.com

It’s easy to be impressed by a killer app. Apple’s iPhone X, for example, is equipped with a TrueDepth camera and Face ID, which are creating new baselines in biometric security. ExtremeTech describes how TrueDepth works: “[It] starts with a traditional 7 MP front-facing ‘selfie’ camera. It adds an infrared emitter that projects over 30,000 dots in a known pattern onto the user’s face. Those dots are then photographed by a dedicated infrared camera for analysis. There is a proximity sensor, [and] an ambient light sensor helps the system set output light levels.”

The sophisticated enabling technology behind Face ID is the VCSEL (vertical-cavity surface-emitting laser), used in arrays, transmitting huge amounts of data with ultralow power at low cost.

I’m impressed by the technology, of course, but not blinded. I’m equally curious to know about the early sparks that led to an idea for a laser that operates contrary to convention. A VCSEL beam — unlike traditional edge-emitting lasers — emits perpendicular to the top surface. The thinking, like the photons, diverged.

Rarely is it possible to trace the history of contrary ideas, or any ideas; they do not emerge smoothly from an unbroken chain of events. Instead, they erupt, flow, confront, emerge. In German, the word entstehung loosely translates as “formation” or “genesis,” but it also carries connotations of the messy interplay necessary for ideas to mature.

Beyond the first spark, the researchers, scientists, and explorers involved in the decadeslong maturation of an idea persist. From my desk in Massachusetts, I have a vision of their persistence; I imagine notes, sketches, equations, late-night conversations — a slow “turning over of stones” and a ferment that has evolved into today’s fast and powerful technology.

When considering VCSELs, here are a few names to know, visionaries who persisted — implicit in the ferment.

Ivars Melngailis. Kenichi Iga. Larry Coldren. Sam McCall. Axel Scherer. Jack Jewell. Jim Tatum.

Click here to learn how their contrary laser is impacting us today.