High energy, low repetition rate, photonic crystal fiber generated supercontinuum for nanosecond to millisecond transient absorption spectroscopy

Abstract: High energy density per pulse (−15dBmnm−1) supercontinuum (SC) source has been developed as a probe for transient absorption (TrA) spectroscopy of systems with lifetimes from nanoseconds to a few milliseconds. We have generated a 600–1600nm, broadband SC by pumping a 15m photonic crystal fiber (PCF) with relatively high power, 7ns, 1064nm pulses. The SC generated at peak pump power of 7.1kW was randomly polarized and maintained a stable output (6.5% rms average power; 9.1% rms shot-to-shot power). Co-pumping with both 1064 and 532nm light extended the wavelength range of the SC by about 20%, to 500–1700nm. Power conversion efficiency and spectral flatness were improved as well. In the visible range, the single-pump SC shows a flatness of 5dB while the dual-pump SC exhibits 3dB. In the NIR (1100–1600nm), the flatness in single- and dual-pump configurations were 3 and 2dB, respectively. Optically induced fiber breakdown was characterized. [Copyright &y& Elsevier]