Absolute frequency control of semiconductor lasers

Multiwavelength communication systems will require precise frequency setting of the laser sources to allow channel identification and avoid interference. Although semiconductor lasers already show very impressive frequency stability with time, their absolute frequency setting has to be controlled periodically by external mean. The unique way to achieve worldwide traceable and reproducible absolute frequency setting is to frequency-lock the laser to an atomic or molecular resonance. However, the available resonances are limited and are often positioned at odd values. Therefore, it is necessary to develop a mean to translate the characteristics of the master laser to more suitable laser frequencies