Remote Frequency Stabilization Technique by Using MZI-AWG and Supervisory Frame Transfer in Coexistence-Type WDM-PON

We propose a remote frequency stabilization technique for upstream signals in coexistence-type wavelength-division-multiplexed passive optical networks (WDM-PONs). It is based on dithering the transmission spectra of the demultiplexer to create a frequency monitor; supervisory frames that contain frequency information are transferred from the central office to the optical network unit through a downstream signal. To achieve a wide capture range for feedback control, the DEMUX is built as a new planer lightwave circuit that incorporates a Mach-Zehnder interferometer (MZI) and two arrayed waveguide gratings (AWGs). Experiments show that the deviation in laser-diode (LD) frequency can be suppressed to ±3.5 GHz by using the supervisory frames with the fixed time interval of 2 ms even though the LD frequency is expected to drift by ±25 GHz against the ITU-T grid over its lifetime. An analytical estimation also shows that the proposed technique can effectively reduce the power budget required for the transceivers for upstream signal transmission with no significant decrease in the main signal bandwidth.