Yb-doped Photonic Crystal Fiber Laser Research Articles

980-nm Q-switched photonic crystal fiber laser by MoS2 saturable absorber

We demonstrate a 980-nm Q-switch Yb-doped photonic crystal fiber laser by a multilayer molybdenum sulfide polymer composite as the broadband saturable absorber which is prepared by the chemical vapor deposition method. We achieve passively Q-switching operations at 978 nm with the pulse width of 2.7 and 0.63 μs, corresponding to the repetition rate of 212 and 221 kHz, respectively. The maximum output power is 127 mW. It is the first time that MoS2 Q-switched Yb-doped photonic crystal fiber laser at 980 nm is demonstrated. The experimental results show that few-layer MoS2 is a promising broadband saturable absorber material.

Study on self-pulsing dynamics in Yb-doped photonic crystal fiber laser

In this paper, we present the experimental and analytical study of self-pulsing dynamics in Yb-doped photonic crystal fiber laser in single-end and double-end pumping configurations. It has been found that the intensity of self-pulses is considerably higher in the single-end pumping configuration as compared to that for double-end pumping configuration. In both the cases, it was noted that when the pump power was sufficiently high, intensity and occurrence of the self-pulses were reduced. However, the reduction in the intensity of self-pulses was significant in the double-end pumping. Experimental study shows that occurrence of self-pulses is due to the initial relaxation oscillations and re-absorption and there is no role of nonlinear phenomena in the generation of self-pulses. The rate equation analysis shows that the non-uniformity in single pass distribution of upper level population along the fiber length is responsible for re-absorption and hence self-pulsing. In the case of single-end pumping, single pass distribution of upper level population along the fiber length has more non-uniformity as compared to the double-end pumping, and hence stronger self-pulsing is observed.

Design and fabrication of Gires–Tournois interferometers for Yb-doped photonic crystal fiber laser system

A Gires–Tournois interferometer (GTI) with large dispersion compensation was designed and fabricated according to the requirement of the Yb-doped photonic crystal fiber laser system. The designed GTI can provide an average group delay dispersion (GDD) of −1500 fs2 and a high reflectance (>99.7%) from 1030 to 1050 nm. The Ion-assisted Deposition (IAD) technique was utilized to manufacture the mirror. Good agreement between the measured and designed results both for reflectance and GDD was achieved. The reflectance during 1030–1050 nm was above 99.5% and the GDD ripple was less than ±300 fs2. The GTI was used both in the intracavity dispersion compensation and extracavity pulse compression for the Yb-doped photonic crystal fiber laser system. A mode-locked soliton pulse with a 506-fs duration was recorded. An extracavity pulse compression test showed that the GTI had identical pulse compression capability as the conventional grating pairs while the energy loss was obviously reduced. Our results demonstrated that the HDM, which was able to provide quite a large amount of negative dispersion (∼−8×104 fs2), could be an ideal alternative to replace the dispersive compensating grating pairs for the dispersion compensation of the Yb-doped photonic crystal fiber laser system.

Millijoule-level Yb-doped photonic crystal fiber laser passively Q-switched with AlGaInAs quantum wells

We report on a millijoule-level Yb-doped photonic crystal fiber (PCF) laser passively Q-switched with AlGaInAs quantum wells (QWs). Three types of AlGaInAs devices with different QW numbers are fabricated to investigate the performance. With 50 groups of three AlGaInAs QWs as a saturable absorber (SA), the PCF laser generates an average power of 7.1 W with a pulse repetition rate of 6.5 kHz at a pump power of 16 W, corresponding to the pulse energy of 1.1 mJ. The maximum peak power is up to 110 kW.

High power Q-switched Yb-doped photonic crystal fiber laser producing sub-10 ns pulses

We report on a Q-switched fiber laser producing pulse durations well below 10 ns by using a short-length ytterbium-doped rod-type photonic crystal fiber as gain medium. At repetition rates up to 100 kHz pulse energies up to 0.5 mJ and average powers in excess of 30 W have been obtained in single-transverse mode beam quality. The compact short pulse laser system possesses further power and energy scaling potential.