Wavelength stabilization technique using dithering-induced AM cancellationfor DWDM systems

We proposed and demonstrated a novel wavelength stabilization technique fur dense wavelength division multiplexing (DWDM) systems using dithering-indu ced AM cancellation which improves both wavelength stability and data trans mission performance. Our wavelength stabilization technique consists of an optical frequency discriminating function and a function for canceling AM c omponents induced by frequency dithering of the light source. The frequency discrimination in this technique is based on an FM-AM conversion effect, o btained by interaction from frequency dithering of the light with the band- pass characteristic of an arrayed-waveguide grating (AWG) multiplexer. The AM cancellation function was added to suppress optical frequency discrimina ting Errors occurring due to AM components induced by frequency dithering i n this wavelength stabilization architecture. In this scheme, an electro-ab sorption (EA) modulator is employed not only for modulating high-speed data traffic but also for suppressing AM components induced by frequency dither ing on the light signal. Since the EA modulator is usually used for modulat ing high-speed data traffic, dedicated optical devices are not required for suppressing the AM components. The wavelength stability of a light sourer can therefore be enhanced with simple architecture. In the demonstration, a reduction of fluctuations within 50 MHz versus changes in the modulation i ndex, and long-term stability within 320 MHz after more than 60 hours was a chieved in 10 Gbit/s NRZ transmission. We also confirmed that the proposed AM cancellation technique effectively reduces the transmission penalties du e to frequency dithering in 10 Gbit/s NRZ data transmission performance.