Unipolar and Subcycle Extremely Short Pulses: Recent Results and Prospects (Brief Review)

In recent years, progress has been made in obtaining extremely short electromagnetic pulses up to single-cycle and unipolar half-cycle pulses. For pulses with such a dependence of the electric field strength on time, the behavior and properties of such radiation and its interaction with matter acquires a number of new features. For extremely short unipolar pulses an important role in the interaction with matter is played by the electric pulse area (the integral of the electric field strength over time at a given point in space). The review presents the latest theoretical and experimental results in the field of obtaining and interaction of extremely short pulses with extended resonant media and individual microobjects (atoms, molecules, nanostructures). The results of new publications are discussed, in which phenomena are predicted that arise during the coherent propagation of extremely short pulses in resonant media—self-compression and self-stopping of a pulse in a homogeneous medium. Particular attention is paid to the effect of ultrashort pulses on microobjects from the point of view of the recently introduced concept of “interference” of pulse areas (electrical area and envelope area). The research results presented in the review relate to a new direction in modern optics that has emerged recently—“Optics of unipolar and subcycle light,” which is becoming an actively developing area of modern physics.