Investigation of short-wave edge in high power supercontinuum with different peak power

摘要

The peak power of pump pulse is a key factor in the generation of supercontinuum source. Observably, as the peakpower of the pump pulse increases, the spectral range of the supercontinuum becomes wider. In order to study the blueshift limit of PCF fiber at different peak powers, in our experiment, the change in peak power is achieved by introducinga different length of chirped fiber after the oscillator to vary the pulse width. The pump source is a self-made laser withpulse duration, operating wavelength and repetition rate of 12 ps, 1064 nm and 68 MHz, respectively, which are injectedinto the photonic crystal fiber after three stages of amplification. Finally, a supercontinuum with an average power of358 W in the spectral range of 466 nm to 2400 nm was achieved. Experiments have shown that the introduction of largepositive chirp has a significant effect on the supercontinuum of the 10 W class, but for a supercontinuum with asufficiently high average power (over 100 W level supercontinuum spectrum). after the peak power threshold isexceeded, further blue shift of the spectrum cannot be achieved by increasing the peak power, but the high peak powerhelps to improve the spectral flatness of the supercontinuum. The four-wave mixing, dispersive wave generation,radiation trapping with the soliton play much important role in the blue-shift of SC spectrum, but the short-wave edge islimited by the group velocity matching condition, which is determined by the dispersion characteristics of the PCF, notonly peak power of the pump pulse. In order to further extend the short-wave spectrum, other methods are required, forexample, changing the structural characteristic of the PCF, etc.