  An efficient plasma compression scheme by azimuthally-polarized (AP) light is
proposed. An AP light possesses a donut-like intensity pattern, enabling it to
compress and accelerate ions toward the optical axis across a wide range of
parameters. When the light intensity reaches the relativistic regime of
$10^{18}$ $\mathrm{W}/\mathrm{cm}^{2}$, and the plasma density is below the
critical density, protons can be compressed and accelerated by the toroidal
soliton formed by the light. The expansion process of the soliton can be well
described by the snow-plow model. Three-dimensional (3D) particle-in-cell (PIC)
simulations show that within the soliton regime, despite the ion density
surpassing ten times of the critical density, their energy is relatively low
for efficient neutron production. When the light intensity increases to
$10^{22}$ $\mathrm{W}/\mathrm{cm}^{2}$, and the plasma density is tens of the
critical density, deuterium ions can be compressed to thousands of the critical
density and meanwhile accelerated to the MeV level by a tightly-focused AP
light during the hole-boring (HB) process. This process is far more dramatic
compared to the soliton regime, and can produce up to $10^{4}$ neutrons in a
few light cycles. Moreover, in the subsequent beam-target stage, neutron yield
is assessed to reach over $10^{8}$. Finally, we present a comparison with the
results by a radially-polarized (RP) light to examine the influence of light
polarization.
