Thick volume hologram for microwave frequency band: design, fabrication, and test

Abstract

A method is proposed for the fabrication of thick volume holograms for applications in the microwave-frequency band. Artificial dielectric technology is used to realise the transverse modulation of the refractive index. Design guidelines and principles are explained. A prototype is fabricated based on the proposed method and is tested to demonstrate its validity. The efficiency of the prototype in the transmission mode is approximately 70%, which is a typical performance for ‘thick phase holograms’. To the best of the authors’ knowledge, this is the first time that a thick volume hologram is demonstrated in the microwave-frequency band. The same technology has then been used to design and fabricate a multiplexed hologram which contains two sets of interference patterns. Measurements demonstrate high coupling between the corresponding object and reference beams and low crosscoupling between the two sets. It is also demonstrated that this technology can be used to realise beam-splitting which has potential application in power-combining. These particular designs suggest the possibility of duplicating optical holographic applications of the hologram technology in the microwave-frequency band.