OPTICAL SWITCHES BASED ON MAGNESIUM LANTHANIDE ALLOY HYDRIDES

It is shown that thin layers of palladium coated magnesium lanthanide alloys reversibly go through an optical transition by variation of the hydrogen concentration, just as has recently been shown for pure lant hanides. With these layers optical switches can be constructed that ex hibit three different optical states: a color-neutral transparent stat e at high hydrogen concentration, a nontransparent dark absorbing stat e at intermediate hydrogen pressures, and a highly reflective metallic state at low hydrogen pressures. The ratio in transmission between th e transparent state and the reflecting state is more than 1000. (C) 19 97 American Institute of Physics.