A system (2900; 3000; 3100; 3200), comprising: an optical beam source configured to generate an optical beam; a first length of fiber (104; 204; 1100; 1200; 1300; 1400; 1406; 1500; 1500; 1600) operably coupled with the optical beam source and configured to receive the optical beam therefrom, the first length of fiber comprising a first refractive index profile (212; 1102; 1202; 1302; 1402; 1412; 1504; 1602); a perturbation device (110; 210) operably coupled with the first length of fiber and configured to modify the optical beam traversing through the first length of fiber; a second length of fiber (108; 208; 1700; 1800; 1900; 2000; 2100) operably coupled with the first length of fiber and configured to receive the modified optical beam therefrom, wherein the second length of fiber is a multicore fiber including a plurality of confinement regions (216, 218, 220; 1704, 1706, 1708; 1808, 1810, 1812; 1904, 1906, 1908, 1910; 2004, 2006, 2008; 2104, 2106, 2108; 2922, 2924, 2926, 2928; 3016; 3018; 3020; 3110, 3112, 3114; 3216, 3218) defining a second refractive index profile (1702; 1802; 1902; 2002; 2102) that is different from the first refractive index profile, the plurality of confinement regions including a first confinement region and a second confinement region, wherein the second length of fiber is configured to confine the modified optical beam to at least one of the confinement regions; and a beam shaping assembly (2920; 3002; 3102; 3202) operably coupled with the second length of fiber, wherein the beam shaping assembly is configured to receive the modified optical beam from the second length of fiber, adjust one or more beam characteristics of the modified optical beam, and direct the adjusted optical beam to a downstream process. an optical beam source configured to generate an optical beam; a first length of fiber (104; 204; 1100; 1200; 1300; 1400; 1406; 1500; 1500; 1600) operably coupled with the optical beam source and configured to receive the optical beam therefrom, the first length of fiber comprising a first refractive index profile (212; 1102; 1202; 1302; 1402; 1412; 1504; 1602); a perturbation device (110; 210) operably coupled with the first length of fiber and configured to modify the optical beam traversing through the first length of fiber; a second length of fiber (108; 208; 1700; 1800; 1900; 2000; 2100) operably coupled with the first length of fiber and configured to receive the modified optical beam therefrom, wherein the second length of fiber is a multicore fiber including a plurality of confinement regions (216, 218, 220; 1704, 1706, 1708; 1808, 1810, 1812; 1904, 1906, 1908, 1910; 2004, 2006, 2008; 2104, 2106, 2108; 2922, 2924, 2926, 2928; 3016; 3018; 3020; 3110, 3112, 3114; 3216, 3218) defining a second refractive index profile (1702; 1802; 1902; 2002; 2102) that is different from the first refractive index profile, the plurality of confinement regions including a first confinement region and a second confinement region, wherein the second length of fiber is configured to confine the modified optical beam to at least one of the confinement regions; and a beam shaping assembly (2920; 3002; 3102; 3202) operably coupled with the second length of fiber, wherein the beam shaping assembly is configured to receive the modified optical beam from the second length of fiber, adjust one or more beam characteristics of the modified optical beam, and direct the adjusted optical beam to a downstream process. <EOS>