OPA-driven hollow-core fiber as a tunable, broadband source for coherent multidimensional spectroscopy

Despite the impressive abilities of coherent multi-dimensional spectroscopy (CMDS), its' implementation is limited due to the complexity of continuum generation and required phase stability between the pump pulse pair. In light of this, we have implemented a system producing sub-10 fs pulses with tunable central wavelength. Using a commercial OPA to drive a hollow-core fiber, the system is extremely simple. Output pulse energies lie in the 40-80 mu J. range, more than sufficient for transmission through the pulse shaping optics and beam splitters necessary for CMDS. Power fluctuations are minimal, mode quality is excellent, and spectral phase is well behaved at the output. To demonstrate the strength of this source, we measure the two-dimensional spectrum of CdSe quantum dots over a range of population times and find clean signals and clear phonon vibrations. This combination of OPA and hollow-core fiber provides a substantial extension to the capabilities of CMDS. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement