We demonstrate a novel single-polarization Er(3+)-doped fiber Fabry-Perot laser. The all-fiber Fabry-Perot cavity is simple inasmuch as it is formed by only two fiber-based components, a fiber loop polarizer and a wavelength-selective fiber loop reflector. The threshold power is 6.5 mW, the slope efficiency is 12.2%, and the extinction ratio is approximately 25 dB.