LASER FREQUENCY STANDARDS IN THE NEAR-INFRARED, COINCIDING WITH THE OPTICAL-FIBER TRANSMISSION BANDS

Laser frequency standards in the 1.3- and 1.5-mum optical-fiber commun ication bands are reviewed in the wider context of laser frequency mea surement across the spectrum. A survey of the telecommunication indust ry has found a need for two standards per band, accurate to 1 part in 10(9). Some potential sub-Doppler standards are listed, which may meet this and higher-accuracy requirements. All are atomic transitions, ty pically in excited states or requiring frequency doubling to access th em; laser cooling is possible for rubidium. Wider benefit might accrue to frequency measurement from extending the use of point-contact meta l-insulator-metal diodes for frequency mixing, and from eventual trans mission of a standard frequency on fiber networks.