Session C17 - Lasers/Semiconductor Devices.
FOCUS session, Monday morning, March 12
Room 304, Washington State Convention Center
The polarization properties of monochromatic and quasi-monochromatic electromagnetic radiation are well understood. A circularly polarized (CP) field, for example, is described in the time domain by an electric field vector that follows a circular or nearly circular trajectory of slowly varying radius. For an electromagnetic pulse of single-cycle duration, however, this picture breaks down. We show that the correct description of the orthogonal field components is no longer a simple shift in time, as in circular motion. Rather, a more general Hilbert transform relationship between the orthogonal field components must be applied. These predictions have been verified through the use of single-cycle pulses of far-infrared radiation generated by optical rectification from femtosecond laser pulses and transformed into the CP state by a Fresnel rhomb. Real-time measurements of the electric field vector of the CP far-IR pulses are performed by electro-optic sampling of the field with a time synchronized femtosecond laser pulse. Possible applications of this radiation for far-infrared spectroscopy will be discussed.