Any glass shop should have what you need. Home improvement centers too.
If you are wanting something other than glass, I use two thin sheets,of mirror back to back instead for clients. Gives the illusion of glass with total privacy. Looks awesome.
If you’re talking about dual pane window exterior glazing, you’ll need to go to the manufacturer.
Not quite enough information to understand what type of application you're looking for. Exterior? Interior? Privacy?
One of the coolest things I've seen is a large mural type landscape scean poster cut to fit the spaces to create a faux view through the French door.