Abstract: An optical fiber coupler configured to couple signal beams into a non-circularly shaped output optical beam or device is provided. The coupler includes an adiabatically tapered optical device. The tapered optical device has a core taper ratio equal to the ratio between a second core diameter and a first core diameter and a mode taper ratio equal to the ratio between a second mode field diameter and a first mode field diameter. The mode taper ratio is greater than the core taper ratio. A spacing between adjacent cores at the output end is less than a spacing between adjacent cores at the input end by approximately the core taper ratio, thereby increasing brightness of a combined output optical signal relative to the combined brightness of the plurality of input optical fibers by approximately a factor equal to the ratio of the mode taper ratio to the core taper ratio.

Abstract: Optical fiber source for providing polarized optical pulses, comprising a Q-switched fiber laser for providing substantially unpolarized seed pulses of optical energy, where the Q-switched fiber laser can comprise a laser cavity having a Q-switch and an optical fiber comprising a gain medium, where the optical fiber need not be a polarizing or polarization maintaining optical fiber; a passive polarizing element arranged to receive and substantially polarize the substantially unpolarized seed pulses; and a polarization maintaining fiber amplifier arranged for receiving the polarized seed pulses. The polarization maintaining fiber amplifier can comprise a selected polarizing or polarization maintaining fiber having a core comprising a gain medium for amplifying the substantially polarized seed pulses, where the core can be normally multimode at a an operating wavelength of the optical fiber source. The fiber amplifier can provide substantially polarized output pulses.

Abstract: Optical fiber source for providing polarized optical pulses, comprising a Q-switched fiber laser for providing substantially unpolarized seed pulses of optical energy, where the Q-switched fiber laser can comprise a laser cavity having a Q-switch and an optical fiber comprising a gain medium, where the optical fiber need not be a polarizing or polarization maintaining optical fiber; a passive polarizing element arranged to receive and substantially polarize the substantially unpolarized seed pulses; and a polarization maintaining fiber amplifier arranged for receiving the polarized seed pulses. The polarization maintaining fiber amplifier can comprise a selected polarizing or polarization maintaining fiber having a core comprising a gain medium for amplifying the substantially polarized seed pulses, where the core can be normally multimode at a an operating wavelength of the optical fiber source. The fiber amplifier can provide substantially polarized output pulses.