Actively tunable thin films for visible light by thermo-optic modulation of ZnO

作者：Battal Enes^*; Okyay Ali Kemal

来源：Physica Status Solidi A-Applications and Materials Science, 2016, 213(5): 1340-1345.

DOI：10.1002/pssa.201532393

• antireflection coatings
• ellipsometry
• Fabry-Perot resonance
• modulators
• thermo-optical materials
• zinc oxide

Applications of active control of light matter interactions within integrated photonics, hyper-spectral imaging, reconfigurable lasers, and selective bio-surfaces have enormously increased the demand for realization of optical modulation covering the spectrum from ultraviolet (UV) up to infrared (IR) wavelength range. In this study, we demonstrate ZnO-based actively tunable perfect absorber operating within UV and visible spectrum with more than 5 nm shift in the resonant absorption wavelength. Using spectroscopic ellipsometry technique, we extract temperature-dependent optical constants of atomic layer-deposited ZnO within 0.3-1.6 and 4-40mm spectra. We also observe bandgap narrowing of ZnO at elevated temperatures due to lattice relaxation verified by the red-shift of phonon-modes. At around its bandgap, refractive index variations up to 0.2 is obtained and ZnO is shown to exhibit thermo-optic coefficient as high as 9.17 x 10(-4) K-1 around the bandgap which is the largest among well-known large bandgap materials.

• 出版日期2016-5