Abstract: A method to increase the output power of monolithic narrow-linewidth Yb-doped fiber amplifiers by suppressing simulated Brillouin scattering. The fiber amplifier employs a co-propagating geometry and is seeded with broad- (source 2) and narrow- (source 1) linewidth signals that are sufficiently different in wavelengths to allow for efficient gain competition and favorable temperature profile at the output end of fiber. The broadband seed signal possesses the higher emission and absorption cross sections. If source 2 is also given sufficiently greater input power than source 1, it will be amplified to its maximum value as the seed signals reach the middle portion of the gain fiber. Beyond that portion, the signal having the lower emission and absorption cross sections (signal 1) will continue to experience gain by power transfer from both signal 2 and the pump light, attaining a power output well beyond what the maximum output would have been had the amplifier been illuminated with a single frequency beam.

Abstract: Stimulated Brillouin scattering (SBS) in a photonic crystal fiber is suppressed by doping the individual core segments such that the Brillouin frequency of each segment is sufficiently different from the neighboring segments that Brillouin scattered light from one core segment sees negligible gain from the other core segments, whereby higher power narrow-linewidth optical fiber amplifiers and lasers may be obtained. The optical properties of the guiding medium are preserved through the careful design of the core and the lattice structure.

Abstract: A method to increase the output power of narrow-linewidth rare earth-doped fiber amplifiers by suppressing simulated Brillouin scattering. The fiber amplifier is seeded with two or more lasers having frequencies and input powers that are sufficiently different. The seed signal with the highest emission cross section (e.g., signal 2) initially experiences the greatest gain. If signal 2 is also given sufficiently greater input power than signal 1, it will be amplified to its maximum value before the seed signals have reached the midpoint of the gain fiber. Beyond that point, the signal having the lower emission and absorption cross sections (signal 1) and significantly lower input power will continue to experience gain by power transfer from both signal 2 and the pump light, attaining a power output well beyond what the maximum output would have been had the amplifier been illuminated with a single frequency beam.

Abstract: Method and apparatus are provided for NLO switching by first providing a phase-matched SHG grating which outputs a reinforced SHG beam only when two input beams of frequency (.omega.) are present in two modes of such wg. The so encoded NLO switch is operated by directing at least two input pulsed laser beams of frequency (.omega.) into the two modes of the wg to generate a reinforced pulsed output SHG beam and output same from the wg in an NLO switching process. The two input beams desirably have a separate pulse train and the spatial and temporal overlap of the input beams are adjusted such that at least some of the pulses of each pulse train sufficiently overlap to generate and output reinforced SHG pulse signals and thus output an on-off data signal. A detector then reads and processes the output signals. Such NLO switch will allow integrated circuitry to operate at faster rates and to allow, eg.

Abstract: Method and apparatus are provided for NLO switching by first providing an amorphous waveguide (wg) encoded with gratings which produce phase-matched SHG in at least two wg modes. Then two input pulsed laser beams (preferably beams split from the same source) are directed into and propagate in the wg, one beam in each of the two modes so as to generate two phase-matched SHG beams in one mode by the use of gratings of the invention. The fundamental beams produce SHG beams which are about 180.degree. out of phase with each other. The two input beams are adjusted such that some of the pulses in their respective pulse trains overlap spatially and temporally, interfere and are cancelled to output a data signal in a resultant pulse train. A detector then reads and processes the output signals. Such NLO switch will allow integrated circuitry to operate at faster rates and to allow, e.g.