Generation of 2-26 cm{sup}(-1) bandwidth near-transform limited pulses in mid-IR via difference frequency mixing of chirped pulses

摘要

Time-resolved infrared spectroscopy requires spectral resolution ranging from as good as ～cm{sup}(-1) for spectrally complex systems to <100 cm{sup}(-1) for simpler molecules. This sets the usable pulse durations from ～15 p5 to >150 fs respectively assuming near bandwidth-limited light pulses, that are desirable to obtain the best time resolution. Optical parametric amplification (OPA) is a well-established technique to produce wavelength tunable pulses in IR spectral region. However, a particular OPA system usually produces pulses of fixed duration, which reduces its range of applicability. An OPA producing pulses with tunable bandwidth would be of great value. This would allow maximizing the time resolution for a specific experiment without sacrificing the spectral resolution.