Femtosecond fiber lasers together with nonlinear fibers are compact, reliable, all-fiber supercontinuum sources. Maintaining an all-fiber configuration, however, necessitates pulse compression in an optical fiber, which can lead to nonlinearities for subhundred femtosecond, nanojoule pulses. In this work we show that using large-mode-area fibers for pulse compression mitigates the nonlinearity, resulting in compressed pulses with significantly reduced satellite pulses. Consequently, supercontinua generated with these pulses are shown to have as much as a 10 dB increase in coherence fringe contrast. By using a hybrid highly nonlinear fiber-photonic crystal fiber, the continuum can be extended to visible wavelengths while still maintaining high coherence.

Supercontinuum extending to visible wavelengths is generated in a hybrid silica nonlinear fiber pumped at 1560 nm by a femtosecond, erbium-doped fiber laser. The hybrid nonlinear fiber consists of a short length of highly nonlinear, germano-silicate fiber (HNLF) spliced to a length of photonic crystal fiber (PCF). A 2 cm length of HNLF provides an initial stage of continuum generation due to higher-order soliton compression and dispersive wave generation before launching into the PCF. The visible radiation is generated in the fundamental mode of the PCF.

We have built and tested an interferometric fiber-optic gyroscope made with photonic crystal fiber. This paper reports the test results and examines the advantages of photonic crystal fiber for this type of gyroscope.

A silica optical fiber doped with Sb is fabricated with a refractive-index profile that is comparable with standard single-mode fiber. In D(2)-loaded samples, we observe UV photosensitivity with an initial refractive-index-modulation growth rate six times higher than that of the equivalent Ge-doped standard fibers. Enhanced temperature stability of the Bragg grating strength up to 200 degrees C is also observed. Grating growth kinetics in the Sb-doped fiber is compared with those of other Ge-doped photosensitive fibers.

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