Self-wavelength initialization method for the Bragg-grating based tunable light source in WDM passive optical network.

We propose a self-wavelength initialization method for the waveguide Bragg-grating based tunable external cavity laser. Reflection characteristics of the Bragg-grating, and the wavelength routing property in the wavelength division multiplexing-passive optical network (WDM-PON) were used in our proposed method. By adding a cost-effective and low- power broadband light source in the central office, the tunable laser can align its output wavelength with the wavelength at the center of the pass band of the WDM multiplexer. This method can be applicable for the Bragg-grating based tunable laser, which is placed either in the central office or in the subscriber region. The operating principle and the feasibility of the proposed method were described by evaluating the transmission performance. By using our initialization method, a tunable laser with a Bragg-grating can be used as a true colorless light source for the WDM-PON.