  We utilize an exact variational numerical procedure to calculate the ground
state properties of a polaron in the presence of Rashba and linear Dresselhaus
spin-orbit coupling. We find that when the linear Dresselhaus spin-orbit
coupling approaches the Rashba spin-orbit coupling, the Van-Hove singularity in
the density of states will be shifted away from the bottom of the band and
finally disappear when the two spin-orbit couplings are tuned to be equal. The
effective mass will be suppressed; the trend will become more significant for
low phonon frequency. The presence of two dominant spin-orbit couplings will
make it possible to tune the effective mass with more varied observables.
