Thermal darkening of one-dimensional photonic crystal containing tellurium suboxide

• Published in: Optical materials 2019-02, Vol.88, p.167-175
• Main Authors: Kong, Heon, Lee, Hyun-Yong
• Format: Article
• Language: English
• Subjects: Defect layer; One-dimensional photonic crystals; Photonic band gap; Tellurium suboxide; Thermal darkening
• ISSN: 0925-3467; 1873-1252
• DOI: 10.1016/j.optmat.2018.11.032

The purpose of this study is to experimentally and theoretically evaluate the optical properties of a one-dimensional photonic crystal (PC) with a defect layer before and after an annealing procedure. A sputtering technique with high index (TeOx) and low index (SiO2) materials was used to fabricate the 1D PC with a defect layer. The chemical and structural analysis of a single layer TeOx thin film was evaluated by X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), and X-Ray Diffraction (XRD). The optical constant of the single layer was also determined based on the envelope method from transmittance spectra measured by ultraviolet visible near-infrared spectrophotometry (UV-VIS-NIR). The measured reflectance spectra of the 1D PC were compared with the results simulated using the transfer matrix method (TMM) before and after the annealing procedure. A photonic bandgap (PBG) appears within the desired, near-infrared (NIR), region. The defect mode in the 1D PC was observed at λ = 1455 nm within the PBG of λ = 1235–1723 nm (Δλ = 488 nm). The reflectance spectra overall shifted toward longer wavelength due to thermal darkening effect resulting from the thermally induced optical property changes. •TeOx thin film showed thermal darkening effect after annealing procedure.•Sputtered TeOx/SiO2 1D PC was analyzed before and after annealing procedure.•Measured reflectance spectra agreed well with the simulated results.•Reflectance spectra shifted toward longer wavelength after the annealing procedure.