  Limited by the difficulty in acceleration synchronization, it has been a
long-term challenge for on-chip dielectric laser-based accelerators (DLA) to
bridge the gap between non-relativistic and relativistic regimes. Here, we
propose a DLA based on a spatio-temporal coupling (STC) controlled laser pulse,
which enables the acceleration of a non-relativistic electron to a sub-MeV
level in a single acceleration structure (chirped spatial grating). It provides
high precision temporal and spatial tuning of the driving laser via the
dispersion manipulation, leading to a synchronous acceleration of the velocity
increasing electrons over a large energy range. Additionally, the STC scheme is
a general method and can be extended to driving fields of other wavelengths
such as terahertz pulses. Our results bring new possibilities to MeV-scale
portable electron sources and table-top acceleration experiments.
