Infrared absorption in a quantum wire in the presence of spin-orbit coupling: a technique to measure different types of spin-orbit interaction strengths

We show that the dominant absorption peak due to inter-subband transition in a gated quantum wire, with two occupied subbands, will split into a main peak and two satellite peaks if both Rashba and Dresselhaus spin-orbit interactions are present. One satellite peak will be red-shifted, and the other blue-shifted. From the relative intensity of either satellite peak, and the magnitude of the red- or blue-shift, we can determine both Rashba and Dresselhaus interaction strengths separately, if we also carry out a Hall measurement to determine the carrier concentration and a quantized conductance step measurement to determine the energy separation between subbands. This method may be a convenient alternative to usual magneto-transport measurements used to measure spin orbit interaction strengths. It is also more powerful because it allows us to measure the strengths of the two types of interactions separately.