In this example, we will model an optical phased array using liquid crystals (LCs) which can be used for beam steering.
Beam steering using an LC optical phased array is considered in this example. The figure above shows the model of the phased array in FDTD. In this model, the orientations of the LCs rotate anti-clockwise from the bottom to the top as a function of y. Due to the change of the LC orientation, the light passing through the LC region feels different refractive index depending on the position y, which results in an optical path length difference as shown blow at the exit surface. As a result, the phase from is tilted and the beam steering can be achieved.
The following image shows the real part of Ey from the profile monitor where we can see the tilted phase fronts exiting the LC slab.
Applying far field transformation to the power monitor located just in front of the exit surface, which is named far field in the simulation file, we can get the angular distribution of far field intensity at 1m away from the device. The result is shown below and we can see that the beam is steered about 0.8 degrees. The following plot was generated by calculating the far field with an angular resolution of 5000 points.
- X. Wang, B. Wang, P. J. Bos, J. E. Anderson, J. J. Pouch, and F. A. Miranda, "Finite-difference time-domain simulation of a liquid-crystal optical phased array" J. Opt. Soc. Am. A Vol. 22, No. 2, pp. 346-354, (2005)