What does the 光 in 时间之光 mean?
时间之光 is the long version of 时光.

时间之光 ＝ 时光 ＝ 韶光 ＝ 光阴 ＝ time

光 ＝ 时 ＝ time

《重编国语辞典》[名]4


  时间。如：“光阴”、“时光”。
  唐．李白〈前有一樽酒行〉二首之一：“青轩桃李能几何？流光欺人忽蹉跎。”


 国学大师 - 光 〈名〉(8)


  光阴,时光 [time]
  始屏忧以愉思,乐兹情于寸光。——南朝宋· 鲍照《观漏赋》


They all have the same meaning, the time.

穿过时间之光 is just a writing technique.
It is the same as 随着时间, with time.

We can also interpret as follows.

The light won't stop.

穿过时间之光 is similar to 经过时间的流逝 or 随着时间的流逝, as time goes by.