Thickness‐Controlled Molybdenum Dielectric Lenses Designed for High‐Frequency Electro‐Optical Applications

Herein, molybdenum thin films of variable thicknesses (70–650 nm) are deposited onto glass substrates by the ion coating technique. The Mo films, which are designed as dielectric lenses, exhibited amorphous structure and stable surface roughness for layers of thicknesses larger than 100 nm. Optical investigations have shown that the transmittance and optical gap of Mo/MoO 3 decreases with increasing dielectric lens thickness. As dielectric lenses, while the dielectric constant increases with increasing film thickness when application is targeted at 1.50 eV and 2.50 eV, the optimum value of thickness suiting ultraviolet applications is 344 nm. Mo‐dielectric lenses showed a highly stable terahertz (THz) cutoff frequency ( ) value for all films thicker than 70 nm. On the other hand, fabricating planar waveguides using Mo‐dielectric lenses and imposing an AC signal between their terminals showed their ability to perform as high‐frequency waveguides with microwave cutoff frequency values exceeding 30 GHz and reaching 74 GHz for 450 nm thick lenses. Both of the photonic investigations and electrical investigations on Mo‐dielectric lenses showed their suitability for high‐frequency applications, including THz and gigahertz technology sectors. The value of the cutoff limit can be controlled by the lens thickness, which showed excellent engineering of the dielectric properties.