High precision self-referenced phase retrieval of complex pulses with multiple-shearing spectral interferometry

We show that using multiple shears in spectral shearing interferometry is a powerful technique for improving precision, thus enabling the measurement of more complex pulses and resolving phase ambiguities. We derive an efficient and robust optimal phase reconstruction algorithm for extracting the spectral phase from interferograms taken at an arbitrary number of different shears. We show that if the shear is easily adjustable then a multishear measurement always offers a superior precision, even when considering the loss of precision of the raw data necessitated by multiple acquisitions. We present numerical examples and demonstrate an experimental implementation of the measurement of a double pulse using two shears.