We report a new approach to obtaining linear-polarization operation of a rare-earth-doped fiber amplifier in which the gain fiber is coiled under tension to induce birefringence. We demonstrated this method by constructing an Er/Yb-doped, double-clad, single-mode fiber amplifier with an output power of 530 mW and a polarization extinction ratio of >17 dB (when seeded with linearly polarized light) at a wavelength of ~1.5 µm . The technique is achromatic, permits single- or multiple-pass operation of the amplifier, requires no additional components in the optical path, leaves the fiber ends unobstructed, and is inexpensive to implement.
© 2000 Optical Society of America
(060.2320) Fiber optics and optical communications : Fiber optics amplifiers and oscillators
(060.2420) Fiber optics and optical communications : Fibers, polarization-maintaining
(140.3510) Lasers and laser optics : Lasers, fiber
(140.4480) Lasers and laser optics : Optical amplifiers
(260.1440) Physical optics : Birefringence
Jeffrey P. Koplow, Lew Goldberg, Robert P. Moeller, and Dahv A.V. Kliner, "Polarization-maintaining, double-clad fiber amplifier employing externally applied stress-induced birefringence," Opt. Lett. 25, 387-389 (2000)