Reconfigurable branching unit for submarine optical communication networks

1. A method for optical communication with a submarine optical network, comprising:

receiving an input signal from a terminal at a reconfigurable branching unit (BU), wherein the BU enables bidirectional transmission between any two terminals;

demultiplexing the input signal into at least one individual waveband using at least one demultiplexer;

passing each demultiplexed waveband through 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;

performing independent per-waveband switching using a demultiplexer-switch-multiplexer (DSM) architecture; and

multiplexing each demultiplexed waveband at each output port using at least one multiplexer to combine signals from different sources, and transmitting combined signals to a destination terminal;

signal switching and dummy light reuse with an interconnected bidirectional architecture and a dual fiber pair between the BU and the branch terminal that allows spectrum reuse between two trunk terminal to branch terminal paths, wherein the dummy light enables amplifier power balancing; and

switching waveband to reduce hardware and enables flexible grid network operation with a uniform loss that offers automatic optical power equalization.

2. The method of claim 1 , wherein the two or more 2×2 optical switches are employed to achieve latching.

3. The method of claim 1 , wherein each signal passes through each of the at least one demultiplexer, the at least one multiplexer, and the two or more 2×2 optical switches at least once.

4. The method of claim 1 , wherein the input signal is demultiplexed into at least one individual wavelength using the at least one demultiplexer.

5. 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, wherein signal switching is done with an interconnected bidirectional architecture and a dual fiber pair between the BU and the branch terminal that allows spectrum reuse between two trunk terminal to branch terminal paths, wherein the dummy light enables amplifier power balancing and waveband switching reduces hardware and enables flexible grid network operation with a uniform loss that offers automatic optical power equalization.

6. The system of claim 5 , wherein an optical network is a submarine optical network.

7. The system of claim 5 , wherein the two or more 2×2 optical switches are employed to achieve latching.

8. The system of claim 5 , wherein each of the at least one demultiplexer, at least one multiplexer, and the two or more 2×2 optical switches pass each signal through at least once.

9. The system of claim 5 , wherein the at least one demultiplexer demultiplexes the input signal into at least one individual wavelength.

10. 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;

signal switching and dummy light reuse with an interconnected bidirectional architecture and a dual fiber pair between the BU and the branch terminal that allows spectrum reuse between two trunk terminal to branch terminal paths, wherein the dummy light enables amplifier power balancing; and

switching waveband to reduce hardware and enables flexible grid network operation with a uniform loss that offers automatic optical power equalization.

11. The method of claim 10 , wherein an optical network is a submarine optical network.

12. The method of claim 10 , wherein latching is achieved by employing at least one passive, static multiplexer and at least one passive, static demultiplexer.

13. The method of claim 10 , wherein one or more latching 1×2 optical switch is employed to achieve latching.

14. The method of claim 10 , wherein the input signal is demultiplexed into at least one individual wavelength using the at least one demultiplexer.