All-fiber-based optical frequency generation from an Er-doped fiber femtosecond laser

Generating precise optical frequencies with a functional power is necessary in many fields of science and technology. Here we demonstrate an all-fiber-based apparatus built to generate near-infrared frequencies directly from an Er-doped fiber femtosecond laser. In our apparatus, only a single resonance mode is extracted at a time on demand via a composite fiber filter comprised of a Fabry-Perot etalon with a Bragg grating. The extracted mode having weak 40 nW power is amplified to 20 mW by means of optical injection locking to a distributed-feedback laser diode under phase-stabilization control. The amplified final output signal yields a frequency stability of 2 parts in 10(15) at 10 s averaging with a narrow linewidth of less than 1 Hz. This apparatus is precise and immune to environmental disturbance, thereby being well suited to on-site near-infrared applications of frequency calibration, spectroscopy, and optical clocks.