A metasurface optical pulse shaper includes a metasurface with superpixels disposed on an entry side of the metasurface and a wire grid polarizer disposed on an exit surface of the metasurface for controlling a phase, amplitude, or polarization of an optical pulse, wherein the metasurface in combination with dispersers provide for optical shaping of the optical pulse. A process for optically changing a pulse shape includes dispersing a primary optical pulse; separating spatially, by frequency, primary frequency waves; changing, by superpixels, a relative phase of the primary frequency waves and producing phase waves that are separated spatially by frequency and phase; and producing a plurality of shaped frequency waves such that, from an individual phase wave, a shaped frequency wave is produced that separated spatially by frequency and phase, such that a superposition of shaped frequency waves produce a shaped optical pulse that has pulse shape that is different than the primary optical pulse.
Ultrafast laser pulse shaping is a well-developed field with available commercial products. Typically, the amplitude, phase or polarization of the light is controlled by placing a spatial light modulator (SLM) at the focus of the first mirror, in a technique known as Fourier-transform pulse shaping. The SLM controls each spectral component (color, in the case of visible light) present within the laser pulse separately. The main problem in pulse shaping today is the limited spectral resolution offered by an SLM due to the relatively small total size and relatively large pixel size. The holy grail in pulse shaping is the control over individual frequency comb lines in a wide pulse spectrum pulse train, which has not yet been accomplished via SLM due to the mentioned limitations. This problem is resolved with this new NIST technology. NIST uses a relatively new device known as a dielectric metasurface in place of the SLM to control independently the amplitude (through polarization) and phase of individual spectral components of an ultrafast pulse.
The metasurface has several advantages over an SLM. They offer lower cost, larger total size, smaller pixel size, higher diffraction efficiency, and higher damage threshold.