Fig. 2.

Process required to steer the beam is to (a) calculate the required phase pattern on the SLM and (b) display the phase pattern on the SLM and reflecting light off the SLM. Steps to calculate the phase pattern are as follows. (i) Assume there is an incident field $E_A$ with the desired steering angle incident on the metasurface (MS). Calculate the transmitted scattered field $E_B$. (ii) In order to match the SLM pixel size to the scattered field speckle size, $E_B$ is low-pass filtered to be $E_B^L$. (iii) $E_B^L$ is phase conjugated to get the phase pattern required on the SLM, $E_{\text{cal}}$. (b) The beam can then be steered by displaying the phase of $E_{\text{cal}}$ on the SLM and reflecting light off the SLM and into the metasurface. SLM, spatial light modulator.