Broadband tuning of a long-cavity all-fiber mode-locked thulium-doped fiber laser using an acousto-optic bandpass filter.

A long-cavity passively mode-locked thulium-doped all-fiber laser is reported incorporating a tapered acousto-optic tunable bandpass filter (AOTBF). The operation of the AOTBF relies on the intermodal coupling between core and cladding modes when a flexural acoustic wave propagates along an 80 µm tapered fiber. The filter works in transmission and exhibits a 3 dB bandwidth of 9.02 nm with an insertion loss of 3.4 dB. The laser supports ultrashort pulse generation at a low repetition rate of 784.93 kHz. Optical pulses with 2.43 nm of optical bandwidth and 2.1 ps pulse duration were obtained in a broad tuning range from 1824.77 to 1905.16 nm.

Abrupt-tapered fiber filter arrangement for a switchable multi-wavelength and tunable Tm-doped fiber laser.

A switchable and tunable multi-wavelength Tm-doped fiber laser is successfully demonstrated using a filter constructed with two tapered fiber elements in the cavity. The proposed system design uses a low-cost simple filter that allows stable dual, triple, quadruple, and quintuple-wavelength emission operation in the region around 1.9 µm. In the dual wavelength regime, the laser is capable of independently tuning each wavelength. For switching and tuning, a curvature is applied to the tapered fibers.

Initial conditions for dissipative solitons in a strict polarization-controlled passively mode-locked Er-Fiber laser.

We report the dynamics of dissipative solitons in a ring cavity passively mode-locked fiber laser with a strict control of the polarization state. We study the relation between the polarization state of the pulses propagating in the cavity and the regimes of generation. We have found that at pulse ellipticities between 5° and 15°, the laser generates one bunch of pulses in the cavity, while at higher ellipticities the laser generates multiple bunches. At constant ellipticity we rotated the polarization azimuth and observed a regime transition from the generation of noise-like pulses (NLP) to that of soliton crystal. The NLP regime was found when the azimuth was rotated towards smaller low-power transmission through the polarizer. The number of solitons in the soliton crystal also depended on the azimuth in a straightforward way: the higher the initial transmission, the bigger the number of solitons.