Patent ID: 7391562

Claim:
An apparatus, comprising: an input port at which an optical signal is received; a first optical isolator, coupled to the input port, receiving the optical signal from the input port and outputting a first optical isolator signal; a first stage optical amplifier, coupled to the first optical isolator, receiving the first optical isolator signal from the first optical isolator, and outputting a first stage amplified optical signal; an optical device, coupled to the first stage optical amplifier, including an optical filter and a second optical isolator, the optical device receiving the first stage amplified optical signal and outputting an optical device signal; a second stage optical amplifier, coupled to the optical device, receiving the optical device signal, and outputting a second stage amplified optical signal; a third optical isolator, coupled to the second stage optical amplifier, receiving the second stage amplified optical signal, and outputting an output optical signal; an output port outputting the output optical signal from the third optical isolator; and a pumping light source coupled to the first stage optical amplifier and the second stage optical amplifier via a fourth optical isolator.