We demonstrate stable single-frequency and polarization operation of a traveling-wave, Er(3+)-doped fiber loop laser by incorporating an unpumped Er(+3)-doped fiber section butted against a narrow-band feedback reflector. The saturable absorber acts as a narrow bandpass filter that automatically tracks the lasing wavelength, thus ensuring single-frequency operation. Output powers up to 6.2 mW at 1535 nm were obtained for launched pump powers of 175 mW at 1064 nm. At this output, the relative intensity noise was less than -112 dBy/Hz at frequencies above 200 kHz and a laser linewidth of less than 0.95 kHz, whereas the lasing frequency was observed to drift slowly (~170 MHz/h) because of environmental effects.

Abstract:We report the fabrication of a large mode area tellurite holey fiber from an extruded preform, with a mode area of 3000μm 2 . Robust single-mode guidance at 1.55μm was confirmed by both optical measurement and numerical simulation. The propagation loss was measured as 2.9dB/m at 1.55μm. A broad and flat supercontinuum from 0.9 to 2.5μm with 6mW output was obtained with a 9cm length of this fiber.

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We propose and demonstrate a polarimetric Er(3+) -doped fiber distributed-feedback laser sensor in which a force applied transversely along the fiber laser induces a birefringence that gives rise to a change in the beat frequency between the two orthogonally polarized laser modes. We measure a sensitivity of ~9.6 GHzysNymmd, a wide dynamic range with stable two-mode operation for frequency separations up to 50 GHz, and high sensor resolution owing to the narrow beat frequency bandwidth of <10 kHz. The temperature sensitivity is dominated by the temperature dependence of the inherent birefringence, which was measured to be -130 kHz/ degrees C. The sensor permits independent pressure-force and temperature measurements.