Deterministic generation of tailored subcycle optical waveforms---from unipolar to multipeak structures---remains a challenge in ultrafast science. We propose an approach based on space-time field transformation via structured plasma mirrors. It is shown that tailored plasma density profiles can produce customizable subcycle optical waveforms---from rectangular to multipeak profiles---via direct spatial-to-temporal mapping. The underlying single-atom dynamics are validated by three-dimensional time-dependent Schr\"odinger equation simulations. A scaling relation =2L/c is established, linking the spatial period L of the density modulation to the temporal separation between waveform features. This relation may be viewed as a temporal analog of Bragg diffraction. The methodology provides a route to optical field control in attosecond science and petahertz electronics, where spatial material structure directly influences temporal light structure. The extension of this approach to solid-state platforms, including composition-modulated superlattices, is briefly discussed.
Arkhipov et al. (Tue,) studied this question.