For applications in portable electronic devices and machine vision, a small sized focus-tunable lens or lens system is highly desired. Materials with electrically tunable optical refractive indices are required in these fields. A functional material consisting of a WS₂ thin film on a SiC substrate was synthesized and reported in our investigation. A 15-nm-thick WS₂ film was deposited on an n-doped SiC substrate (7.37  ×  10¹⁹  cm^−  3) by pulsed laser deposition. The optical refractive index of the WS₂  /  SiC material was found to be electrically tunable. The value of the effective optical refractive index ranged from 4.03 to 5.84, which implies a 44.9% variation in the refractive index change, at a wavelength of 460 nm under an applied external DC voltage modulated in the range of 0 to 7 V. We also found experimentally that the focal length of the plane lens was tunable from 184 to 156 mm at a wavelength of 650 nm with the applied voltage ranging from 0 to 7 V. Our investigation presents a new way to modulate the refractive index and make the compact focus-tunable lens design convenient.

Photoelectric functional material WS₂ thin film on SiC substrate was synthesized. Both 15 and 150 nm thickness of WS₂ film were deposited on an n-doped SiC substrate (7.37  ×  10¹⁹  cm^−  3) by pulsed laser deposition method. Optical properties of the WS₂  /  SiC material were discovered. (I) a photovoltaic effect: (1) there is a cutoff wavelength λ_c (661 nm), which means the wavelength of an incident monochromatic light must be less than λ_c in order to have the photovoltaic effect; (2) the incident light must be polarized. (3) It was found that the maximum open circuit voltage output is 6.3 V in a condition of 40 mW @ 532 nm. (II) Wavelength blueshift: when a laser of 532 nm is used in the experiment to incident perpendicularly through the thin layer WS₂  /  SiC film stack, which is driven by an external electric field, it is found that the 532-nm photons are blueshifted 1.33 nm under a 30 V (DC) voltage. We also find that the blueshift of the laser wavelength is tunable with the applied voltage. Inverse Compton scattering of the photon by both electron and hole is used to explain this blueshift, the consistency of experimental results and the theoretical calculation for the wavelength blueshift was found.