Table 3 Comparison of OAM Manipulation Technologies for FSO Terminals.
Parameter | SLM | Dielectric metasurface | Notes |
|---|---|---|---|
Phase control | Programmable (8–12 bit resolution) | Static (pre-fabricated) | SLM offers dynamic reconfiguration; the metasurface profile is fixed. |
Refresh rate | \(\le\) 1 kHz | Not applicable | SLM refresh limits real-time switching speed. |
Insertion loss | 10–20% | 20–40% | Metasurface loss varies with material and design. |
Crosstalk (SXR) | 15–20 dB | 15–25 dB | Higher-order OAM modes show increased sensitivity to imperfections. |
Field of view | Limited (pixel-constrained) | Wide (typically >30\(\vphantom{0}^\circ\)) | SLM field of view is restricted by pixel count and fill factor. |
Cost | Significantly higher | Potentially lower at scale | Metasurfaces benefit from batch fabrication and semiconductor-process compatibility. |
Integration potential | Moderate | High | Metasurfaces enable ultra-thin, planar integration with detectors. |
Alignment sensitivity | High (\(\mu\)rad-level precision) | Moderate | SLM requires precise angular and translational alignment. |
