Sagnac Interferometer for Two-Dimensional Spectroscopy in the Pump-Probe Geometry

Bandgap Inhomogeneity of a PbSe Quantum Dot Ensemble from Two-Dimensional Spectroscopy and Comparison to Size Inhomogeneity from Electron Microscopy

“…The 2D spectrometer uses an actively stabilized Mach–Zehnder interferometer to generate the pump pulse pair and a Sagnac interferometer to enhance signal interference detection. , The collinear pump-pulse pair with delay τ = t b – t a excites the sample first and is followed by noncollinear pulse c after a relaxation time, T . At a given T , τ is scanned symmetrically and the spectrum of transmitted pulse c + signal is directly measured at every τ delay.…”