Dynamic gain induced pulse shortening in Q-switched lasers
ABSTRACT We describe a novel mechanism of pulse shortening in a Q-switched laser induced by the gain compression effect under strong pumping conditions. The pulse shortening requires a large variation of the gain excursion during the saturation process and benefits from the large volume of the gain medium. The effect has been experimentally demonstrated using a passive Q-switched Tm/Ho-doped fiber laser that shows gain-induced pulse compression from 800 ns down to 160 ns when the pump threshold is exceeded by 15 times.
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- "The pulse repetition rate increased from ß35 to ß60 kHz when the pump power was enlarged, while the output pulse width decreased from ß3.54 to ß1.71 μs. These temporal behaviours that depended on the pump power are a phenomenon typically observed in saturable absorber-based passively Q-switched lasers , , . Finally, we measured the average output power and its corresponding pulse energy, as shown in Fig. 7. "
ABSTRACT: We experimentally demonstrate that a bulk-structured Bi2Te3 topological insulator (TI) film deposited on a side-polished fiber can act as an effective Q-switch for a 1.89-μm laser. Our bulk-structured Bi2Te3 TI film with a thickness of ~31 μm, was prepared using a mechanical exfoliation method, and the fabricated film was transferred onto a side-polished SM2000 fiber to form a fiberized saturable absorber based on evanescent field interaction. By incorporating the saturable absorber into a thulium (Tm)-holmium (Ho) co-doped fiber-based ring cavity, it is shown that Q-switched pulses with a minimum temporal width of ~1.71 μs can readily be produced at a wavelength of 1.89 μm. The output pulse repetition rate was tunable from ~35 to ~60 kHz depending on the pump power. The maximum output pulse energy was ~11.54 nJ at a pump power of 250 mW. The output performance of our laser is compared to that of the 1.98-μm Q-switched fiber laser based on a nanosheet-based Bi2Se3 TI demonstrated previously by Luo et al.IEEE Journal of Selected Topics in Quantum Electronics 07/2014; 21(1). DOI:10.1109/JSTQE.2014.2329934 · 3.47 Impact Factor
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ABSTRACT: We experimentally demonstrate the use of a side-polished birefringent fiber with index matching gel spread on the flat side as a passive Q-switch for the implementation of an all-fiberized, erbium-doped fiber (EDF)-based Q-switched laser. It is shown that Q-switched pulses with a ~2.5-μs temporal width are readily achievable from an EDF ring cavity using the side-polished birefringent fiber-based Q-switch. The tuning capability of the pulse width and the repetition rate by changing the pump power is also investigated.Applied Physics B 08/2013; 112(1). DOI:10.1007/s00340-013-5397-2 · 1.63 Impact Factor
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ABSTRACT: A technique for stabilizing the repetition frequency of a passively Q-switched laser is presented using an optically driven surface-normal semiconductor modulator. A method is capable of significant reduction of the timing jitter in a passively Q-switched laser by optical triggering the saturable absorber semiconductor reflector. The experimental demonstration using passively Q-switched ytterbium-doped fiber laser shows the jitter reduction by factor of 1.66??10(3) from 50 mus down to 30 ns.Optics Express 07/2008; 16(12):8720-6. DOI:10.1364/OE.16.008720 · 3.49 Impact Factor