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An optically controllable Er/Yb co-doped random fiber laser with a random multi-phase shifted fiber Bragg grating pumped by a 980 nm laser is proposed. We used a 980 nm laser diode to laterally pump an Er/Yb co-doped fiber with a random multi-phase shifted fiber Bragg grating. Through changing lateral pump location, control of laser outputs was achieved. As a result, outputs of one or two main laser peaks were obtained by changing the locations of the Er/Yb co-doped fiber being laterally pumped.

A tunable erbium-doped fiber (EDF) laser assisted by a random fiber grating introduced by an fs-laser and a tunable fiber Bragg grating is demonstrated. The tuning range is up to 4.45 nm（ 1548.04 -1552.49 nm）. Due to the half-opened laser cavity design and the efficient gain from the pumped EDF, the measured threshold pump power is 18 mW, and the slope efficiency is up to 13.2%.

In recent years, there is a very fast development in high power fiber laser technology. However, problems like strong nonlinear effect, thermal injury at the fiber end facet and so on arise with increase of the laser power. One of the promising methods is to use rare earth-doped photonic crystal fiber (PCF) with a large mode area as gain medium, but the commonly used free-space coupling method limits efficiency, flexibility and stability of fiber lasers. Here we use a kind of double-clad large-mode-area PCF of 500 μm outer diameter to splice with the traditional solid fiber and achieved a high power coupling ratio up to 72%. We also optimize the end facet quality of the PCF at the output port to obtain a good output.

A magnetic field sensor based on a novel phase-shifted fiber Bragg grating with magnetic fluid is proposed and experimentally demonstrated. It is fabricated by cleaving a uniform fiber Bragg grating at the center point, introducing a micrometre gap as a phase-shift and then filling the gap with magnetic fluid. External applied magnetic field changes refractive index of the magnetic fluid, leading to a wavelength shift of the phase-shifted induced transmission peak. By detecting transmission peak wavelength shift with magnetic field intensity, optical measurement of magnetic field is realized. Experimental results show a linear response of wavelength shift to magnetic field intensity with a high sensitivity of 2.4 pm/Oe in the testing magnetic field intensity range from 0 to 120 Oe.