Social media web site Facebook (Palo Alto, CA) has some 300 million active users and attracts millions of new users every week. Among the many challenges for the company that come along with such popularity is keeping up with the consequent demand for bandwidth. Last year, Facebook network architect Donn Lee noted his company's need for 100 Gbit/s networking (see http://bit.ly/c4EjrF). And now the first commercial 100 Gbit/s link is up and running. Turned on last December by Verizon, this high-speed fiber-optic link connects Paris and Frankfurt and represents an impressive optical communications milestone–though it's been a long time coming, says contributing editor Jeff Hecht (see page 51). Other 100 Gbit/s link deployments are already in the works and there seems little doubt that additional milestones will be announced this month at the OFC/NFOEC conference in San Diego, CA (see www.ofcnfoec.org).
The field of optical biological imaging in various forms has been very active of late, reaching some of its own milestones. Besides the emergence of a strong OCT market, in vivo optical molecular imaging is poised to move into clinical use (see http://bit.ly/c3eY9m), and in the lab regular advances enable, for instance, tracking a single cell in vivo during its growth. A novel technique called swept field confocal microscopy improves live-cell imaging by enabling dynamic events to be captured quickly in high resolution (see page 55).
Two other articles this month highlight very different aspects of photonics. Our cover story describes how computer-controlled motorized mirror mounts enable rapid recycling of the world's largest x-ray generator by providing unattended realignment of its beam-steering optics (see cover and page 31). And efforts to keep up with the demand for more peak power from petawatt-class solid-state lasers have led to fabrication of the world's largest Ti:sapphire crystals–200 mm in diameter. Crystal size is a factor limiting the output energy in these lasers, and even larger 250 mm diameter crystals are close behind as manufacturers keep pushing their crystal growth technology (see page 37).