Liquid immersed pumped solid state laser

A liquid immersed pumped solid state lasing system comprising a light source and a lasing element spaced from the light source. The light source and the lasing element are mounted in an insulated container. The top of the container is open for inputting a clear cryogenic cooling liquid into the container to totally immerse the light source and the lasing element in the liquid. Heat transfer occurs by conduction from the light source and the lasing element to the liquid thereby cooling the light source and the lasing element to cryogenic temperatures. The container has a window for the output of laser light. A plurality of electrical leads which are superconducting at cryogenic temperatures are attached to the light source. When the leads are connected to a power supply outside the container, the light source directs light on the lasing element so that the lasing element is excited and transmits a light output through the window.