We report wavelength-tunable operation of a Tm-doped silica fiber laser by using a force-induced long-period fiber grating (LPFG) formed in a fiber ring resonator. The laser output wavelength is tuned by moving the transmission passband that is generated between adjacent resonance wavelengths due to the force-induced LPFG. By changing the grating period around 900 μm, we control the laser output wavelength between 1845 and 1930 nm.

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We present an all-fiber tunable bandpass filter based on a combination of a force-induced long-period fiber grating and a fiber coil made along a double cladding fiber. The transmission wavelength can be tuned to be in a range of more than 100 nm by changing the grating period mechanically. We can control the transmission amplitude of the bandpass filter by adjusting the periodic force on the double cladding fiber. The ambient temperature causes a positive shift in the transmission wavelength. Such a device is useful for tunable laser applications and fiber-optic sensors.

We present wavelength tuning operation of a Tm-doped silica fiber laser pumped by a laser diode emitting at 1.63 µm. Wavelength tuning is achieved by two nonidentical mechanical long-period fiber gratings (LPFGs) induced in a single-mode fiber using coil springs. The inter-resonance-mode passband, which is formed between the rejection bands due to the core-to-cladding mode coupling, dominates the gain peak in the fiber laser resonator. The oscillation wavelength is controlled between 1865 and 1972 nm by tuning the grating periods of the two LPFGs.

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