2D SLM based optical time delay units (OTDUs) are introduced for radar and wideband signal processing applications. In particular, the mature nematic liquid crystal (NLC) SLM technology is considered for the proposed architecture. A 1 X 2 optical switch is demonstrated using a parallel-rub birefringent-mode NLC cell, a bulk optics cube polarizing beamsplitter, and a sheet polarizer. Switch measurements taken at 633 nm show a > 3400 : 1 or > 35 dB output port optical isolation. The 1 X 2 NLC switch is used to build a 1-bit, 3.33 ns duration free-space OTDU using mirrors and total internal reflection corner prisms. The unit demonstrated a > 30 dB optical signal-to-noise ratio for both delay and no-delay positions.
Nabeel A. Riza,
"Three-dimensional optical time delay units for radar", Proc. SPIE 2026, Photonics for Processors, Neural Networks, and Memories, (9 November 1993); doi: 10.1117/12.163576; https://doi.org/10.1117/12.163576