These stairs take you down to the train platform in Oncle Toms Hütte station (yes there is a station called Uncle Tom's Cabin, click on the link to learn more). Although this station was originaly opened in 1929, the lighting fixtures and bricks seem more modern to me.
There are a few stations that are "aboveground" on the southern end of line 3 and this is one of them. Here you can see the fantastic glass ceiling that brings natural light onto the platform. It's a nice place to wait on a sunny day!