Ultrafast control of deeply subwavelength periodic gratings in resonant medium by few-cycle pulses

摘要

This work studies the possibility of creation of spatial periodic gratings by few-cycle pulses propagating in a resonant medium. Periodic spatial gratings are typically produced via interference of nearly monochromatic light beams but in this case the spatial period is limited by the light wavelength and pulses have to be long in duration and overlapping in space. As a result, it is impossible to achieve the subwavelength grating and to realize the ultrafast control of their parameters. The usage of few-cycle pulses allows to get over these limitations. It is demonstrated that a sequence of coherently propagating non-overlapping few-cycle pulses enables ultrafast control of the population inversion gratings in a resonant medium. Analytical and numerical treatment of the Maxwell-Bloch equations were performed for the density matrix elements and electric field without use of slowly varying envelope and rotating wave approximations. With proper selection of the delay between the successive pulses and their propagation directions it is possible to create and control a population inversion grating with deeply subwavelength spatial period.