No abstract

No abstract

Seventeen glasses in the Ge-As-Se ternary glass-forming region have been fabricated and analyzed to provide input for optical design data and to establish composition-and structure-based relationships to aide development of novel chalcogenide glasses with tailored optical functionality. While known that Ge addition to binary As-Se glasses enhances the mean coordination number (MCN) of the network and results in increased T g and decreased CTE, this work highlights the impact on optical properties, specifically mid-wave (k = 4.515 lm) index and thermo-optic coefficient (dn/dT). Trends in property changes were correlated with an excess or deficiency of chalcogen content in the glassy network as compared to stoichiometric compositions. Transitions in key optical properties were observed with the disappearance of Se-Se homopolar bonds and creation of As-As homopolar bonds which are associated with the Se-rich and Se-deficient regions near the stoichiometry, respectively. A second transition was observed with the creation of GeSe ethane-like structures, which are only present in strongly Se-deficient networks. Fitting dn/dT values with a simplified version of the thermal Lorentz-Lorenz formulation yielded a linear relation between the quantity (n À3 •dn/dT) and the CTE, which can be used to predict compositions with the near-zero dn/dT required for athermal optical systems.

This work reports the processing and properties of a new chalcogenide glass film that can be photo-patterned by multiphoton lithography (MPL) with enhanced post-fabrication stability. Thermally evaporated germanium-doped arsenic selenide [Ge 5 (As 2 Se 3) 95 ] thin films were photo-patterned using the output of a mode-locked titanium:sapphire laser. The morphology, chemical structure, and optical properties of the material were studied before and after photo-patterning and compared for their long-term aging behavior and stability to previously investigated arsenic trisulfide (As 2 S 3) films fabricated using similar MPL conditions. Relative to As 2 S 3 , thermally deposited Ge 5 (As 2 Se 3) 95 is found to offer higher photosensitivity and greater chemical stability after photo-patterning, as evidenced by lack of ageinduced crystallization and reduced feature degradation over a four year aging period. These findings demonstrate the suitability of a new photo-patternable material for the creation of robust, long-lived functional infrared anti-reflective coatings and meta-optics.