  We investigate theoretically the electronic structure and transport for a
two-level quantum wire with Rashba spin-orbit coupling (SOC) under the
irradiation of an external laser field at low temperatures. The photon-induced
transitions between SOC-splitted subbands with the same lateral confinement
quantum numbers and between subbands with different confinement quantum number
are expected. Using the method of equation of motion (EOM) for Keldysh
nonequilibrium Green's functions (NGF), we examine the time-averaged density of
states (DOS) and the spin polarized conductance for the system with photon
polarization perpendicular to the wire direction. Through the analytical
analysis and some numerical examples, the interplay effects of the external
laser field and the Rashba SOC on both the DOS and the conductance of the
system are demonstrated and discussed. It is found that the external laser
field can adjust the spin polarization rate and the transport of the quantum
wire system with some proper Rashba SOC strengths.
