Optical limiter based on epsilon-near-zero materials

The emerging class of epsilon-near-zero materials (ENZ) is a promising candidate for use in non-linear optical applications including optical limiting. The Army is soliciting proof-of-concept efforts to investigate whether limiting devices can be fabricated based on this novel class of materials. Third Floor Materials, Inc. proposes a feasibility study of such a limiting device, based on its expertise surrounding the highest performing ENZ material in the mid-wave IR (3-5 µm wavelength), donor-doped CdO. The proposed effort seeks to demonstrate the Army’s required specifications (one order of magnitude modulation depth, linear transmission) by coupling the non-linear properties of CdO with a resonant antenna system. Using this coupled-resonator approach, the combined optical properties of the system will leverage CdO’s demonstrated non-linear optical effects. The effort will combine FDTD simulations with experimentally derived non-linear optical properties of CdO. The proposal includes simulation methods to capture the energy dependent optical behavior of candidate structures and optimize the device characteristics, particularly modulation depth and linearity of transmission. This approach will allow efficient screening of device structures based on real-world optical properties. If successful, a potential Phase 1 option effort will experimentally demonstrate a proof-of-concept device.