Patent ID: 8380070

Claim:
An upgradeable low-density wavelength division multiplexing (WDM) system, comprising: a transmitter side, comprising an adjustable interleaved multiplexer or a coupler, one or more wavelength conversion units, one or more fixed wavelength multiplexing units, wherein an optical signal output by the wavelength conversion unit is multiplexed through the fixed wavelength multiplexing unit, the optical signal output by the fixed wavelength multiplexing unit is further multiplexed by the adjustable interleaved multiplexer or the coupler; a receiver side, comprising an adjustable interleaved demultiplexer, one or more fixed wavelength demultiplexing units, one or more wavelength conversion units, wherein the adjustable interleaved demultiplexer interleaves and demultiplexes the received optical signal, transfers the interleaved and demultiplexed optical signal to the fixed wavelength demultiplexing unit to complete the demultiplexing of a wavelength signal, and transfers the demultiplexed wavelength signal to the wavelength conversion unit; and a control unit, configured to transmit an adjust command to the adjustable interleaved demultiplexer when a wavelength usage of the low-density WDM system reaches a threshold; wherein the adjustable interleaved demultiplexer is configured to perform adjustment according to the received adjust command until requirements for a demultiplexing parameter of a high-density WDM system are met.