A solid-state laser constructed like a semiconductor diode. At the junction of anode and cathode, electrons and holes come together; when an electron falls into a hole, bandgap radiation is emitted, as in a light emitting diode. Semiconductor lasers are constructed so that the resulting light tends to stimulate other nearby pairs of electrons and holes to undergo the same process, emitting more light. Also called diode laser, laser diode. See more at laser.