⁸¹Kr (t_1/2=229 ka) is a valuable isotope for radiometric dating of water and ice with a dating range from 30 ka to 1.5 Ma. It is produced by cosmic rays in the stratosphere and uniformly distributed in the atmosphere with an isotopic abundance of ⁸¹Kr/Kr ~ 1 ×10^-12. Based on laser cooling, Atom Trap Trace Analysis (ATTA) has enabled ⁸¹Kr analysis at extremely low isotopic abundance levels. However, it has been a challenge to apply ⁸¹Kr dating on ice cores where sample size is limited. Here, we present the realization of an all-optical ATTA system, reducing cross-sample contamination during ⁸¹Kr analysis by two orders of magnitude and the sample size requirement reduces to ~1 kg. Using all-optical ATTA system, we demonstrate ⁸¹Kr dating of 1-kg ice core samples from Taylor Glacier, Antarctica, whose gas ages are precisely known from their stratigraphic alignment. Moreover, we have performed ⁸¹Kr analysis on basal ice samples of GISP2 core, providing constraints on when Greenland Summit was most recently ice-free. The achieved sample size reduction facilitates ⁸¹Kr dating of ice-core sections to address open questions in paleoclimatology such as the evolution of glaciers on the Tibetan Plateau or the stability of the West-Antarctic ice sheet.