Patent ID: 7199919

Claim:
A tunable Raman amplifier for amplifying a WDM optical signal in an amplification medium, comprising: a tunable multimode pump source that includes a tunable semiconductor laser module configured to emit light having multiple longitudinal modes with a center wavelength that is controllably tunable over a predetermined tuning range, and an optical fiber aligned to receive the light from the laser module; an optical coupler configured to optically interconnect the tunable multimode pump source with the amplification medium so as to apply the light to the amplification medium; and a tuning mechanism configured to controllably alter a control characteristic of said tunable semiconductor laser module based on only on a monitored portion of the optical signal in the amplification medium and change said center wavelength from a first wavelength to a second wavelength within the predetermined tuning range, and a controller configured to monitor said monitored portion of the optical signal via a tap downstream, in a signal propagation direction, of the optical coupler.