  Indium arsenide (InAs) nanowires (NWs) are a promising platform to fabricate
quantum electronic devices, among others they have strong spin-orbit
interaction (SOI). The controlled tuning of the SOI is desired in spin based
quantum devices. In this study we investigate the possibility of tuning the SOI
by electrostatic field, which is generated by a back gate and two side gates
placed on the opposite sides of the NW. The strength of the SOI is analyzed by
weak anti-localization effect. We demonstrate that the strength of SOI can be
strongly tuned by a factor of 2 with the electric field across the NW, while
the average electron density is kept constant. Furthermore a simple
electrostatic model is introduced to calculate the expected change of SOI. Good
agreement is found between the experimental results and the estimated Rashba
type SOI generated by the gate-induced electric field.
