Patent ID: 7630127

Claim:
An optical amplifier module, comprising: a first band-splitting module (BSM) coupled to a first communication fiber to receive a first signal propagating in a first direction; a second BSM coupled to a second communication fiber to receive a second signal propagating in a second direction; an amplifier; a third BSM coupled to the first BSM to receive the first signal, coupled to the second BSM to receive the second signal, and coupled to the amplifier, wherein the third BSM is configured to combine the first and the second signals and provide the combined signal traveling in a common direction to the amplifier; a fourth BSM coupled to the amplifier and configured to separate the combined signal into amplified first and amplified second signals; a first filter coupled between the first BSM and the fourth BSM to receive the amplified second signal from the fourth BSM and to propagate the amplified second signal to the first BSM, wherein the first BSM is configured to direct the amplified second signal to the first communication fiber; and a second filter configured to receive the amplified first signal from the fourth BSM and to propagate the amplified first signal to the second BSM, wherein the second BSM is configured to direct the amplified first signal to the second communication fiber, wherein the first and/or second filter is configured to increase an isolation loss of the amplified second signal and/or amplifier first signal, respectively, the increased isolation loss achieved based on the amplified first signal and/or amplifier second signal passing through more optical elements than the combined signal.