RESUMEN
We investigate an innovative multipass-pumping technique in a short photonic crystal fiber laser. The technique is based on simple optical elements and shows, in a power oscillator configuration, highly efficient CW and Q-switched operation of an extremely short fiber laser. We report significantly higher absorption of the pump light, compared to a single-pass configuration, which results in an impressive fourfold increase in slope efficiency, up to 60%. Moreover, we show pulse energy of 1.22 mJ and pulse duration shorter than 12 ns, corresponding to a peak power of more than 100 kW.
RESUMEN
We demonstrate a high peak power, Q-switched pulsed, intracavity coherently combined fiber laser system. The system is based on two Yb-doped, rod-type, photonic crystal fibers which are passively phase-locked and combined into the single output beam in a power oscillator configuration. Experimental evidence indicate that this oscillator system provides record high peak power of â¼ 0.7 MW with pulse duration of â¼ 10 ns at 1 kHz repetition rate. The measured beam quality shows near-diffraction-limited operation of the coherently combined system.
RESUMEN
CF4 gas has a relatively high Raman cross section and a relatively small Raman shift and is an excellent candidate for a gas-filled hollow-core photonic bandgap (HC-PBG) fiber Raman wavelength converter. Here we investigate experimentally the onset and competition between stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS) processes in high-pressure CF4 gas. We focus 532 nm laser pulses into a high-pressure gas cell and measure the SBS and SRS response. The thresholds for both processes decrease with pressure, as expected. However, with short focusing geometries, the SBS threshold is lower than the SRS threshold, and with long focusing geometries, it is the opposite. We further show that with HC-PBG fiber geometry SRS dominates.