Patent ID: 8472486

Claim:
A method of generating a high-power laser output in the 1100 to 1500 nm spectral region with a narrow and controllable linewidth employing a seeded Raman amplifier, the method comprising: a. supplying a zeroth-order Stokes wavelength seed signal having a linewidth broad enough to prevent significant Stimulated Brillouin Scattering and passing the zeroth-order Stokes signal through an isolator to a wavelength division multiplexer; b. supplying a N th -order Stokes wavelength seed signal having a narrow linewidth approximately equal to that of a desired amplified output signal and passing the N th -order Stokes signal through an isolator to the wavelength division multiplexer wherein both the zeroth-order Stokes signal and the N th -order Stokes signal are injected into a core of an optical fiber; c. passing both the Nth-order and zeroth-order Stokes signals through a rare-earth-doped amplifier having at least one stage to amplify the zeroth-order Stokes signal; d. passing an amplified zeroth order Stokes signal and N th order Stokes signal through at least one long period or tilted Bragg grating; e. then passing the amplified zeroth order Stokes signal and the N th order Stokes signal through at least one Raman resonator comprised of a photosensitive Raman fiber with a highly reflective Bragg grating tuned to the zeroth-order Stokes wavelength signal located at an output end of the Raman fiber; f. the Raman resonator lying between a pair of highly reflective Bragg gratings tuned to a first order Stokes wavelength signal, and the pair of highly reflecting Bragg gratings lying between a pair of highly reflective Bragg gratings tuned to a second order Stokes wavelength signal, and repeating until an outermost pair of Bragg gratings is tuned to the N−1 th -order Stokes wavelength signal, and g. the zeroth-order Stokes signal being converted into a first-order Stokes signal, which in turn is converted into a second-order Stokes signal and repeating in turn until an N−1 th -order Stokes signal is obtained that amplifies the N th -order seed signal to generate an amplified N th -order seed signal, which comprises the desired high-powered narrow linewidth output signal.