Process optimization of durable optical coatings for infrared optics

Date

2024-9-3

Author

Bulut, Oguzhan

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For harsh environments, outside windows must resist particle impact, humidity or marine conditions. To increase the durability of these windows, durable coatings must be applied to their outside surface. Possible hard coatings for these like applications are boron phosphide, diamond like carbon (DLC) and germanium carbide (GeC) coatings. GeC is a highly promising durable optical coating due to its excellent properties, including high hardness, high transmittance at infrared region, low absorption coefficient, low stress, and a refractive index that can be tailored by adjusting process parameters. To obtain more durable optical coatings, processes parameters are investigated in detail in this thesis. Environmental tests are conducted to make sure that this coating is suitable for harsh environments. To increase the mechanical durability of these coating DLC coating is applied onto this coating. After process optimization, durable optical coating can resist high humidity, particle impact and marine environment was obtained. With this study, durable GeC films with high hardness (10.1 GPa) and varying refractive indices (2.3-4.1 at 10 μm wavelength) have been produced. This enables the functionally graded coating of these films with different refractive indices, facilitating the creation of antireflection coatings for infrared applications. Using the RF reactive sputtering technique, GeC films with varying refractive indices were produced by altering the process parameters during the deposition.

Subject Keywords

Durable coatings, Germanium carbide, Diamond like carbon, Optical coatings

URI

https://hdl.handle.net/11511/111385

Collections

Graduate School of Natural and Applied Sciences, Thesis