State Of Polarization Controller Research Articles

Dual-wavelength passively Q-switched ytterbium-doped fiber laser using Fe3O4-nanoparticle saturable absorber and intracavity polarization

We have experimentally demonstrated the operation of a dual-wavelength passively Q-switched ytterbium-doped fiber laser by using a saturable absorber (SA) based on Fe3O4 nanoparticles in a magnetic fluid. The SA was fabricated by depositing magnetic fluid at the end of an optical fiber ferrule. By performing adjustments to the pump power and polarization controller state in the cavity, a stable dual-wavelength lasing operation was generated without intracavity spectral filters or modulation elements. The Q-switched laser output was achieved at a pump threshold of 80 mW with a maximum output pulse energy of 38.8 nJ, a repetition rate of 73.4 kHz and a minimum pulse width of 3.4 µs. To the best of the authors’ knowledge, this is the first demonstration of a dual-wavelength passively Q-switched fiber laser using Fe3O4 nanoparticles as the SA in the 1.0 µm operation region.

Generation of stable nanosecond dual-pulse in an erbium-doped fiber laser with normal dispersion

Because of the special needs for nanosecond double pulse applications in micromachining and material processing, we demonstrated a stable nanosecond dual-pulse erbium-doped fiber laser based on nonlinear polarization rotation technology. The fiber laser operates in a normal dispersion regime with a length of 256m OFS-980 fiber. With the pump power of 1120mW, the laser generates a highly stable dual-pulse train with the pulse widths of 6.2ns and 1.2ns respectively. By simply changing the pump power, the pulse width of one of dual-pulse can be tuned from 2.1 to 6.2ns while the other pulse keeping almost the same duration of 1.2ns. The maximum dual-pulse energy is about 72.5nJ with a repetition rate of 783.3kHz. The formation of such nanosecond dual-pulse is attributed to the pulse splitting and depends on the parameters of the laser cavity, such as the cavity-length and the state of polarization controller. The experiment of a single square pulse splitting into different shapes of nanosecond dual-pulse was demonstrated.