Dye laser. Researcher using a tabletop dye laser used to operate an atomic clock. 'Laser' is an acronym of Light Amplification by Stimulated Emission of Radiation. Dye lasers contain a glass cavity holding a solution of organic dye. Energy is pumped into this chamber and the excited dye molecules are then stimulated to release their energy as light of a very pure frequency. The dye laser is used in the clock to excite hydrogen ions contained in an ion trap. Once in this higher energy state, the ions start to oscillate between energy levels. Other lasers are used to count these oscillations to provide extremely accurate time keeping.