Silica waveguide (SiWG) based Dynamic Gain Equalizing Filter (DGEF)

摘要

Equalization of power divergence over the wavelength spectrum is very important in optical WDM networks for optimizing the link performance and maximizing the transmission distance of the link, thereby reducing the cost/bit/km of transmission. In addition to extending the reach of optical networks, the ability from a remote terminal to dynamically equalize power level changes resulting from long-term aging of fibers and components, reduces system maintenance costs of today's point-to-point links. As the network evolves to include optical cross-connects and re-configurable optical add-drop nodes for wavelength agility and dynamic provisioning of bandwidth-on-demand, the dynamic gain equalization function allows the ability to compensate gain variation of the optical amplifiers resulting from varying input power levels. In this presentation we will talk about the DGEF based on silica-on-silicon technology. The device is based on cascading an arrayed waveguide grating (AWG) based demultiplexer which separates the wavelengths into different bands, an array of Mach-Zhender interferometer (MZI) based attenuators, and an AWG-based multiplexer which recombines all the wavelength bands in to one fiber, all of which are monolithically integrated on one die. The dynamic tuning of the attenuation is achieved by varying the phase of one of the arms of the MZI using the thermo-optic effect. We will present the theory of the DGEF, talk about the control algorithm that is used to obtain the control parameters, and discuss the limitations of the device.