Optical filter

An optical filter, comprising:

• a first layer including a first material,
• the first material including an oxide;
• a second layer including a second material that is different from the first material,
• the second material including at least one of a tantalum pentoxide (Ta2O5) material, a magnesium fluoride (MgF2) material, a zirconium oxide (ZrO2) material, or an yttrium oxide (Y2O3) material, and
• the second layer being adjacent to the first layer;
• and
• a third layer including the first material,
• the third layer being a different layer from the first layer, and
• the first material in the third layer being adjacent to the second material in the second layer.

An optical filter, comprising:

• a first layer including a first material,
• the first material including at least silicon and hydrogen;
• a second layer including a second material that is different from the first material,
• the second material including an oxide, and
• the second layer being adjacent to the first layer;
• and
• a third layer including a third material that is different from the first material and the second material,
• the third material in the third layer being adjacent to the second material in the second layer.