| 摘要 |
<p>The invention provides a method an apparatus for imparting phase shift in one or more pulses. The apparatus comprises at least one optical diffraction grating element; where each one of the grating elements comprises a grating having a constant line spacing (d) and a dielectric body in light coupling arrangement with the grating. The dielectric body has a side through which the pulse traverses. The side is at an angle α (alpha) with respect to the grating. Alpha α defines a path of the pulse in the dielectric body corresponding to an incident angle Υi (theta incident) between the path and a plane normal to the grating. The incident angle υi and grating line spacing (d) cooperate to provide negative second-order dispersion (SOD) and negative third-order dispersion (TOD) so as to compensate for any positive SOD and any positive TOD initially present in the pulse.</p> |
