World’s Longest Laser Created

World’s longest laser — channeled through a 270-kilometer fiber optic cable

A 270-kilometer optical fiber has been transformed into the world’s longest laser, a feat its inventors believe will lead to a radical new outlook on information transmission and secure communications. Engineering academics at Aston University are leading research into ultra-long fiber lasers, to create a platform capable of delivering next-generation information transmission, including telecommunications and broadband.

When normal telephone conversations or data sent over the internet are converted to light in order to travel through standard optical fibers the signals lose around five percent of their power for every kilometer they travel. The signals then have to be amplified to ensure they reach their destination, a process which creates background noise and affects the signal’s quality.

Using a physical process called the Raman effect — a natural phenomenon that affects light passing through a material — and fiber Bragg gratings to reflect light at both ends of the fiber, the team can create a uniform distribution of light through a cavity in the optical fiber. This scheme also presents an ultra-long fiber laser offering new opportunities for handling ultra-fast communications at a high operational capacity.

Sergei Turitsyn from Aston University’s Photonics Research team believes the ultra-long Raman fiber laser has pushed laser technology to completely new territories. It increases by a factor of three the Research team’s previous record result with a laser of 75 kilometers, reported in 2006. The UK team has been collaborating with the Instituto de Optica, Madrid, Spain, and Institute of Automation and Electrometry, Novosibirsk, Russia, to achieve this record result, which was presented in a recent issue of Physical Review Letters.

“The demands on communication systems are increasing significantly, particularly with the huge growth of Internet traffic. This technology offers a new platform for improving the speed, reliability and the operational capacity of future optical communication systems,” said Turitsyn. “However, even more interesting is a fundamentally new way the laser is used —as a transmission medium, rather than a source of coherent radiation. Despite extraordinary advances in laser science, only recently have the fundamental limits of laser cavity length become an area of exploration. One important new concept here is that an ultra-long laser cavity implemented in optical fiber can be seen as a new unique type of a transmission medium. This might lead to a radical new outlook on information transmission and secure communications.”