Troubleshooting ultrashort pulse measurement: the coherent artifact and other issues

Abstract

Theoretical limitations of several ultrashort pulse measurement techniques are investigated. Particular attention is paid to the consequences of averaging over many pulses of different shapes. Averaging over many pulses is a very common practice, and if the pulse shape varies then the measurement result will be incorrect. This issue, referred to as a coherent artifact, is simulated for frequency-resolved optical gating using several nonlinearities, spectral interferometry for direct electric field reconstruction, two-dimensional spectral shearing interferometry, self-referenced spectral interferometry using cross-polarized wave generation, and multiphoton intrapulse interference phase scan. The role of measurement feedback in identifying pulse-shape instability is explored where possible. Several techniques receive additional analysis, such as searching for ambiguities or simulating convergence conditions. In addition, a method for intuitively displaying spatiotemporally distorted pulses is explored and developed.