High performance lasers like the LMJ use special glass as the laser medium rather than gas or diodes. It is the only material capable of producing the enormous energy at exactly the wavelength required for fusion experiments.
SCHOTT has been one of the world’s leading manufacturers for more than 30 years. The glass for the LMJ is doped with small quantities of the chemical element neodymium that transmits the laser radiation. Formerly the laser glass was produced in the form of cylinders, but large sheets are also possible now. Amplification of the beam, known as laser pumping, is in consequence more uniform and more effective. The SCHOTT laser glass of the 21st century complies with the highest requirements as regards precision and purity. Because of the large amounts of energy involved, no residual particles of platinum, which are normally present from the production process, are permitted in the glass. They would heat up and destroy the glass. The significant breakthrough from the financial point of view came with the introduction of a continuous melting process for the manufacture of laser glass. The costs for over 4,000 glass plates would otherwise have been unrealistic right from the start.