Seeded Raman amplifier in a nested configuration for generating a 1240 nm laser

摘要

A third-order Stokes signal at the desired output wavelength of 1240 nm and a zeroth-order Stokes pump wavelength at 1066 nm are seeded into a Raman amplifier comprised of two nested resonators tuned to the first-order Stokes line at 1118 nm and second-order Stokes line at 1176 nm, respectively. The pump wavelength is first amplified and then sequentially converted into the first and second-order Stokes wavelengths as the light traverses the nested resonators. The desired third-order Stokes output wavelength is then amplified by the second-order Stokes wavelength as it propagates through the outermost resonator. Each Raman resonator includes a photosensitive Raman fiber located between a pair of Bragg gratings. The linewidths of the various Stokes orders can be controlled through adjusting the resonant bandwidths of the Raman resonators by offsetting, through heating, the reflectivity bandwidths of each pair of Bragg gratings respectively located in the Raman resonators.

主权项

1. A method of generating a high-power laser having a narrow and controllable linewidth employing a seeded Raman amplifier, comprising:
a. supplying a zeroth-order Stokes wavelength seed signal at 1066 nm having a linewidth broad enough to prevent significant Stimulated Brillouin Scattering; b. passing the zeroth-order signal through a first isolator and then into a wavelength division multiplexer; c. supplying a third-order Stokes wavelength seed signal at an input power, having a wavelength equal to a desired output signal wavelength, and having a linewidth approximately equal to that of a desired output signal linewidth; d. passing the third-order Stokes signal through a second isolator and then into the wavelength division multiplexer concurrently with the zeroth-order Stokes signal; e. then inserting both the third-order and the zeroth-order Stokes signals into a rare-earth-doped amplifier, whereupon the zeroth-order Stokes signal is amplified into an amplified zeroth-order Stokes signal; and f. passing the amplified zeroth-order Stokes signal and the third-order Stokes signal output from the amplifier, sequentially through two long period or tilted Bragg gratings respectively tuned to 1176 nm and 1118 nm, situated in series, and then through two nested Raman resonators and a 1066 nm high-reflector Bragg grating tuned to the zeroth Stokes order line at 1066 nm, whereby g. a desired output signal having, the desired output signal wavelength and the desired output linewidth, is emitted with a power amplified relative to the input power.