The basic idea of light waveform synthesis can be described as follows: First, the spectrum of a light waveform is decomposed into its constituent spectral components by a disperser, then, adequate modulators acting on each of this spectral components individually modifies the relative phase (or delay), the amplitude and polarization of these components before they are coherently superimposed again by a combiner to create a desired tailored waveform (Figure 2a)41.
Although, any arbitrary field waveform can be composed by applying the above idea, in reality the arbitrariness is sensitive to two key parameters. These are: first, the spectral resolution of the disperser ( ) which defines the temporal window (T) with in which the control can be exerted. Second, the total bandwidth ( ), this defines the shortest temporal feature ( ) that can be sculpted upon the intensity profile of …show more content…
The supercontinuum is generated based on the nonlinear propagation of the multi-cycle laser pulses, carried at central wavelength ~790nm, and τFWHM pulse duration is ~ 22 fs (in intensity) at 1mJ., in a gas filled hollow core fiber (HCF). Hence, these pulses are focused by a bi-convex lens (f=1.8 m) into the hollow core fiber entrance. The beam size at the focus is ~ 200 µm. The converging beam enters the HCF apparatus chamber, which is schematically illustrated in Figure 3a, through a ~0.5mm fused silica (anti-reflection coated) entrance window mounted in far distance (~80 cm) to reduce the self-phase modulation. The Ne gas pressure has been adjusted inside the chamber to ~2.2bar, in order to yield the broadest spectra. This broadband spectrum exits the capillary through a thin (~0.5 mm) UV-grade fused silica window, which is mounted at Brewster’s angle of ~790 nm at the end of the HCF`s chamber, in order to provide efficient transmission over a broad spectral