How is a Thin Film filter fabricated?（）

• A、The glass core is doped with an Erbium in periodic segments of the fiber.
• B、Layers of high index ?and low index ?material are deposited on a glass substrate.
• C、Thin layers of silica glass are placed onto wafers to produce a prism-like effect.
• D、Fiber is etched with an ultraviolet laser that is precisely spaced for specific wavelength filtering.