Rapid-scanning interferometer for ultrafast pump-probe spectroscopy with phase-sensitive detection

A modified Mach-Zehnder interferometry that uses a rapid-scanning translation stage in combination with a fused-silica photoelastic modulator is described. The interferometer is capable of recording pump-probe absorption-difference signals without loss of intrinsic time resolutions; high sensitivity is possible even when pulse-repetition reduction methods, such as pulse picking or cavity dumping, are used. The interferometer provides the advantage of rapid-scanning methods with phase-sensitive detection without the penalty of pulse distortion.