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2DSI - Two Dimensional Shearing Interferometry

Developed in close collaboration with MIT, Two-Dimensional Spectral Shearing Interferometry (2DSI) is a pulse measurement system that measures an ultrashort pulse envelope by interfering neighboring spectral components, similar to SPIDER. In contrast to SPIDER, however, 2DSI encodes the spectral group delay in the spectrum of a single nonlinearly transformed pulse, rather than two. This avoids the need to calibrate the delay between two pulses to high precision, a potential complication with SPIDER for few-cycle pulses and below. The 2DSI geometry inherently avoids having the pulse pass through any dispersive materials, and uses Type II upconversion with a phase matching bandwidth of nearly an octave.

This makes 2DSI ideally suited to the rigors of measuring sub-two-cycle pulses and beyond.

The interferogram produced by 2DSI is a direct representation of the spectral group delay of the pulse, allowing for reconstruction of the pulse shape without the need for iterative search algorithms. This allows 2DSI to accurately measure the spectral group delay of pulses with time-bandwidth products in excess of 20, precisely resolving all pulse features, such as weak satellite pulses, which other techniques can miss. In fact, 2DSI has measured the spectral phase of a few-cycle pulse to within a phase delay precision of 40 attoseconds over a 400 nm bandwidth around 800 nm. This makes 2DSI one of the most precise and sensitive measurements of ultrafast waveforms available today.

Raw 2DSI tarces from octave spanning laser with spectral group delay overlaid to demonstrate the simple interpretation of the fringes.

Screenshot of the user interface for the 2DSI.

Idesta’s 2DSI implementation automates the measurement process so that the only user intervention required is the initial alignment, which is made simple by a unique green counter propagating alignment laser. The mechanical set-up is based on our proven flexure stage design for all critical components. Long-term hands-off operation was one of the major design goals. A high quality, high dynamic range spectrometer allows to capture the 2DSI as well as the fundamental signal simultaneously.

Specifications

2DSI Sell Sheet