A compact wavelength stabilization scheme for telecommunication transmitters

With the 100/200 GHz channel spacing of current commercial DWDM systems, severe restrictions are imposed on transmitter wavelengths in order to meet crosstalk specifications and ensure reliable operation of the system in all conditions of its 25 years lifetime. While very stable in the short-term, free-running DFB laser transmitters are expected to exhibit long-term wavelength drifts exceeding these requirements, leading to a need for practical wavelength monitoring and control. In this paper we describe a compact dither free wavelength stabilization method based on a Fabry-Perot (FP) filter. While the concept can be implemented in a stand-alone unit, its small footprint allows its incorporation into existing laser modules without increasing either real estate or dissipated power.