Low cost wavelength and power settable source for deployment in WDM networks

A settable wavelength and power light source is presented where the power and wavelength can be chosen among a network/link power and wavelength plan. The laser characterisation method, laser control, hardware implementation and practical results are shown. The module is designed for insertion into an optical WDM (wavelength division multiplexing) network/link subject to a wavelength and power plan. e.g. one of the proposed frequency plans is 191.9 THz to 194.9 THz with a 0.2 THz channel spacing which corresponds to about 1.539 to 1.563 μm with a spacing of ~1.6 μm. A multisection laser is used in the module due to the ability to change its output wavelength and power by varying the currents on each section. Lasers of these type can be widely tuneable, with tuning range of 40 nm or very widely tuneable with tuning range of over 1OO nm, so the module can have a large settable wavelength range. With a knowledge of the laser output characteristics used in the module, the wavelength and power can be set to the desired values used in the WDM network/link wavelength and power plan. One of the main attractions of the presettable module is the ability to set the wavelength and power remotely and in-situ as the network requirements/configurations change. Two characterisation algorithms have been developed to gain this knowledge and are explained. The hardware implementation uses the operating points to change the wavelength and power of the laser by changing the section currents to each operation point using a steering algorithm