British Telecom’s Martlesham Laboratories may not have the world reknown of AT&T Bell Laboratories, but it has a string of firsts to its credit, and it is now claiming another breakthrough in the field of optical transmission. Even with monomode optical cables, repeaters are needed every 100 miles or so, and these presently involve converting the optical signal to an electrical one, amplifying it and generating a new optical signal. Now researchers at Martlesham have discovered a coating for a solid state laser which reduces reflectivity and causes it to operate as a simple optical amplifier, holding out the hope of replacing large and power-hungry repeaters that may have to be installed in inaccessable places, with a tiny crystal optical amplifier. There is no indication of how soon the device could be used commercially, but it has been successfully tested in a 75 mile optical link to Colchester.
