Abstract: Aspects of the disclosure provide for methods and systems for feedback control of mode MUX and DEMUX. An aspect of the disclosure provides for a method associated with a mode MUX. The method includes modulating each WDM signal of a first set of WDM signals with a pilot tone of different frequency. The method further includes spatially multiplexing the first set of WDM signals to generate a multi-mode signal. The method further includes detecting the pilot tones from the multi-mode signal. The method further includes tuning the mode MUX based on the detecting. Another aspect of the disclosure provides for a method associated with a mode DEMUX. The method includes spatially demultiplexing a multi-mode signal into a set of WDM signals. The method further incudes detecting pilot tones from the set of WDM signals and tuning the mode DEMUX based on the detecting.

Abstract: A system for laser phase noise compensation for a fibered communication path, the system being configured for connection with a node of the fibered communication path, including at least one signal splitter optically coupled to a laser source of the fibered communication path, the at least one signal splitter having two output communication path, the communication paths having a path difference therebetween; an integrated coherent receiver (ICR) optically coupled to the first output communication path and the second output communication path; and a digital signal processor (DSP) communicatively connected to the ICR, the ICR being configured to determine, based signals received from the first and second output communication paths, at least one phase noise indication related to phase noise of the laser source, the DSP being configured to determine an estimated laser phase noise based on at least the at least one phase noise indication.

Abstract: Aspects of the disclosure provide for methods and systems for feedback control of mode MUX and DEMUX. An aspect of the disclosure provides for a method associated with a mode MUX. The method includes modulating each WDM signal of a first set of WDM signals with a pilot tone of different frequency. The method further includes spatially multiplexing the first set of WDM signals to generate a multi-mode signal. The method further includes detecting the pilot tones from the multi-mode signal. The method further includes tuning the mode MUX based on the detecting. Another aspect of the disclosure provides for a method associated with a mode DEMUX. The method includes spatially demultiplexing a multi-mode signal into a set of WDM signals. The method further incudes detecting pilot tones from the set of WDM signals and tuning the mode DEMUX based on the detecting.