Vapor cells having optical windows with multilayer coatings

A method of manufacturing a vapor cell, comprising:

• fabricating an optical window by:
• obtaining a substrate having first and second substrate surfaces on opposite sides of the substrate,
• forming a first multilayer coating on the first substrate surface, thereby defining a first window surface of the optical window, the first multilayer coating applying a first stress to the substrate, and
• forming a second multilayer coating on the second substrate surface, thereby defining a second window surface of the optical window, the second multilayer coating applying a second stress to the substrate that counteracts the first stress to the substrate;
• obtaining a dielectric body that has a cavity and an exterior surface that defines an opening to the cavity;
• and
• bonding the first window surface of the optical window to the exterior surface of the dielectric body, the first window surface extending across the opening to the cavity, the second window surface on a side of the optical window opposite the first window surface.