Reconfigurable branching unit for submarine optical communication networks

A system for optical communication comprising:

• a reconfigurable branching unit (BU), configured to receive an input signal from a terminal, wherein the BU enables bidirectional transmission between any two terminals;
• at least one demultiplexer configured to demultiplex the input signal into at least one individual waveband;
• two or more 2×2 optical switches configured to pass each demultiplexed waveband through the two or more 2×2 optical switches, with two or more corresponding 2×2 optical switches for the same demultiplexed waveband provided for transmission in the reverse direction, wherein the optical switches are interlinked, operate concurrently, and have the same switching state;
• a demultiplexer-switch-multiplexer (DSM) architecture configured to perform independent per-waveband switching;
• and
• at least one multiplexer configured to combine signals from different sources by multiplexing each demultiplexed waveband at each output port, and transmitting combined signals to a destination terminal.

A method for optical communication comprising:

• receiving an input signal from a terminal at a reconfigurable branching unit (BU);
• splitting the input signal into at least two paths using at least one 1:2 optical splitter;
• demultiplexing the input signal into at least one individual waveband using at least one demultiplexer;
• selecting and filtering channels of interest of the input signal using a waveband blocker (WB);
• passing each demultiplexed waveband through at least one 1×2 optical switch, with at least one corresponding 1×2 optical switch being provided for transmission of the same demultiplexed waveband in the reverse direction;
• performing independent per-waveband switching using a combined split-and-select (S&S) and demultiplexer-switch-multiplexer (DSM) architecture;
• and
• multiplexing each demultiplexed waveband using at least one multiplexer to combine wavebands from different sources into a wavelength division multiplexed (WDM) signal, and transmitting the WDM signal to a destination terminal.