eous Absolute Frequency Control of Laser nsmitters in both 1.3 and 1.55 pm Bands r tiw avelength Cornrnunic ation S y sterns

Abvtract-Absolute frequency control will be an essential part of future Dense WDM systems. In this paper, we demonstrate two promising techniques that allow the absolute frequency control of an ensemble of laser transmitters operating in both the 1.3 and 1.55 pm bands. First, a Michelson interferometer is absolutely calibrated by means of a frequency-stabilized master UFB laser. This interferometer provides an ensemble of evenlyspaced absolute frequency references that covers both the 1.3 and 1.5s pm regions. Lasers are frequency-locked to transmission nulls of this interferometer with a precision of a few hundred MHz. The second technique allows full flexibility in channel frequency assignment and relies on frequency offset control of an ensemble of Laser sources relative to a master reference laser. The frequency comparator is based on a surface-emitting nonlinear semiconductor multilayer waveguide. This technique provides simultaneous frequency measurement and control of lasers in both bands with a precision of a few GHz.