Opical Amplifier and Method

Abstract

An electro-optic beam controller, material processing apparatus, or optical amplifier, and corresponding methods, can include an actively controlled, waveguide-based, optical spatial mode conversion device. The conversion device can include a coupler, which can be a photonic lantern, configured to combine light beams into a common light beam; a sensor configured to measure at least one characteristic of the common light beam; and a controller configured to modulate optical parameters of the individual, respective light beams to set one or more spatial modes of the common light beam. Actively controlled and modulated devices can be used to maintain a stable, diffraction-limited beam for use in an amplification, communications, imaging, laser radar, switching, or laser material processing system. Embodiments can also be used to maintain a fundamental or other spatial mode in an optical fiber even while scaling to kilowatt power.

1 - 45 . (canceled) 
     
     
         46 . An optical amplifier comprising:
 an actively controlled, waveguide-based optical spatial mode conversion device configured to provide a common light beam; and   a waveguide-based amplifier configured to receive and amplify at least a portion of the common light beam to produce an amplified common light beam.   
     
     
         47 . The optical amplifier of  claim 46 , wherein the amplified common light beam has an optical power on the order of 10 W, 3 kW, or 12 kW. 
     
     
         48 . The optical amplifier of  claim 46 , further comprising:
 a waveguide coupler configured to combine individual light beams carried by respective, individual, optical waveguides into the common light beam to be carried by a common, multimode optical waveguide;   a sensor configured to measure at least one characteristic of the amplified common light beam; and   a modulation controller operationally coupled to the sensor and to a plurality of modulators, each modulator of the plurality of modulators configured to modulate at least one optical parameter of the respective, individual light beams, the modulation controller being further configured to control the plurality of modulators, based on the at least one characteristic of the amplified common light beam, to set one or more spatial modes of the waveguide-based amplifier.   
     
     
         49 . The optical amplifier of  claim 48 , wherein the respective, individual optical waveguides include single-mode or multimode optical fibers. 
     
     
         50 . The optical amplifier of  claim 48 , wherein the plurality of modulators includes at least one of a phase modulator, amplitude modulator, and polarization modulator. 
     
     
         51 . The optical amplifier of  claim 48 , wherein the modulation controller is further configured to control the plurality of modulators to set a fundamental spatial mode and to suppress other spatial modes of the amplified common light beam. 
     
     
         52 . The optical amplifier of  claim 48 , wherein the modulation controller is further configured to control the plurality of modulators to set a doughnut-shaped spatial mode of the amplified common light beam. 
     
     
         53 . The optical amplifier of  claim 48 , wherein the respective, individual, optical waveguides are input waveguides, and wherein the waveguide coupler further includes a plurality of individual, optical output waveguides tapered into the common, multimode optical waveguide, and wherein the modulation controller is further configured to set the one or more spatial modes of the amplified common light beam to route the amplified common light beam selectively to one or more of the output optical waveguides. 
     
     
         54 . The optical amplifier of  claim 48 , wherein the individual light beams carried by the respective, individual, optical waveguides are outputs from one or more photonic lanterns. 
     
     
         55 . The optical amplifier of  claim 48 , further including one or more waveguide-based pre-amplifiers optically upstream from the waveguide coupler and configured to pre-amplify one or more of the individual light beams. 
     
     
         56 . The optical amplifier of  claim 48 , wherein the plurality of modulators are phase modulators, and wherein the modulation controller is further configured to control the phase modulators to modulate an amplitude of the amplified common light beam. 
     
     
         57 . A method of optical amplification, the method comprising:
 applying active control to convert one or more optical spatial modes in a waveguide configured to provide a common light beam; and   receiving and amplifying at least a portion of the common light beam at a waveguide-based amplifier to produce an amplified common light beam.   
     
     
         58 . The method of  claim 57 , wherein combining individual light beams into the common light beam includes combining to produce an optical power on the order of 10 W, 3 kW, or 12 kW. 
     
     
         59 . The method of  claim 57 , wherein applying active control includes:
 combining a plurality of individual light beams carried by respective, individual optical waveguides into the common light beam to be carried by a common multimode waveguide;   monitoring at least one characteristic of the amplified common light beam; and   controlling at least one optical parameter in each, respective individual light beam of the plurality of individual light beams, based on the at least one characteristic of the amplified common light beam, to set one or more spatial modes of the amplified common light beam.   
     
     
         60 . The method of  claim 59 , wherein combining the individual light beams carried by the plurality of respective, individual optical waveguides includes combining the individual light beams from single-mode or multimode optical fibers. 
     
     
         61 . The method of  claim 59 , wherein controlling at least one optical parameter includes controlling at least one of a phase, amplitude, and polarization of the respective individual light beam. 
     
     
         62 . The method of  claim 59 , wherein controlling to set the one or more spatial modes of the amplified common light beam includes setting a fundamental spatial mode of the amplified common light beam and suppressing other spatial modes. 
     
     
         63 . The method of  claim 59 , wherein controlling to set the one or more spatial modes of the amplified common light beam includes setting a doughnut-shaped spatial mode of the amplified common light beam. 
     
     
         64 . The method of  claim 59 , wherein the respective, individual, optical waveguides are input waveguides, and wherein controlling further includes setting the one or more spatial modes of the amplified common light beam to route the amplified common light beam selectively to one or more output optical waveguides tapered into the common, multimode optical waveguide. 
     
     
         65 . The method of  claim 59 , further comprising receiving the plurality of individual light beams carried by respective, individual optical waveguides from one or more photonic lantern outputs. 
     
     
         66 . The method of  claim 59 , further comprising pre-amplifying one or more of the individual light beams at one or more waveguide-based pre-amplifiers optically upstream from the waveguide coupler. 
     
     
         67 . The method of  claim 59 , wherein controlling further includes adjusting the phase modulators to modulate an amplitude of the amplified common light beam. 
     
     
         68 . An optical amplifier comprising:
 means for applying active control to convert one or more optical spatial modes in a waveguide configured to provide a common light beam; and   means for receiving and amplifying at least a portion of the common light beam at a waveguide-based amplifier to produce an amplified common light beam.