Supercontinuum generation in a photonic crystal fiber with two zero dispersion wavelengths

Abstract

We demonstrate supercontinuum generation in a highly nonlinear photonic crystal fiber with two closely lying zero dispersion wavelengths. The special dispersion of the fiber has a profound influence on the supercontinuum which is generated through self-phase modulation and phasematched four-wave mixing and not soliton fission as in the initial photonic crystal fibers. The supercontinuum has high spectral density and is extremely independent of the input pulse over a wide range of input pulse parameters. Simulations show that the supercontinuum can be compressed to ultrashort pulses.

Spectrally-broad coherent anti-Stokes Raman scattering hyper-microscopy utilizing a Stokes supercontinuum pumped at 800 nm

“…The FemtoWHITE CARS SCG module houses a microstructured fibre with two zerodispersion-wavelengths (ZDWs) at 775 nm and 945 nm [19,20]. Originally, the SCG spectra from the FemtoWHITE CARS were modeled using transform-limited 40 fs input pulses, and were studied as a function of pulse energy rather than peak intensity [19].…”

“…Originally, the SCG spectra from the FemtoWHITE CARS were modeled using transform-limited 40 fs input pulses, and were studied as a function of pulse energy rather than peak intensity [19]. With such short pulses, cascaded nonlinearities provide efficient wavelength shifting and broadening, rapidly evolving spectral weight beyond the ZDWs, and leaving the region between the pumping wavelength (790 nm) and the ZDWs largely devoid of spectral power.…”

“…In the future, careful power-tuning of the Stokes spectrum and a judicious choice of filters/combiners will allow access to lower frequencies and a broader span of the CARS spectrum. Furthermore, while the current work focused on power-tuning the supercontinuum generation in a commercial PCF module with a 12-cm fibre, studying the possibility of utilizing smaller lengths of the same fibre [19] to obtain higher spectral powers below 945 nm is a promising avenue for future research. …”

“…SF-CARS has been implemented using three distinct experimental approaches: by using two synchronized laser sources to generate pump/probe and Stokes [15]; by using a single spectrally-broad sub-25-fs laser source with intra-pulse filtering to generate the pump/probe and Stokes [16,18]; or by using a fs-laser-pumped photonic crystal fibre (PCF) source to generate a supercontinuum from which some (or all) of the pump/probe/Stokes beams are derived [5,9,10,14,19]. Implementations of SF-CARS that use a single spectrally-broad femtosecond laser source have been successful in performing both CARS imaging and dense spectral acquisition, albeit with the added challenges and costs of utilizing an ultra-broadband laser system.…”

“…The PCF most typically used for SF-CARS [20] has been selected by some groups for the stability and spectral density of its generated supercontinuum [14,[21][22][23]. Previous work by Hilligsoe et al highlighted this fibre's efficiency in generating supercontinuum beyond its two zero-dispersion wavelengths (ZDWs), which are 775 and 945 nm, using sub-70 fs input pulses [19]. However, within the two ZDWs, this fibre has not been shown to generate supercontinuum with enough spectral intensity to be useful for CARS.…”