a spaser or plasmonic laser is a type of laser which aims to confine light at a subwavelength scale far below rayleigh's diffraction limit of light, by storing some of the light energy in electron oscillations called surface plasmon polaritons. the phenomenon was first described by bergman and stockman in 2003. the word "spaser" is an acronym for "surface plasmon amplification by stimulated emission of radiation". the first such devices were announced in 2009 by three groups: a 44-nanometer-diameter nanoparticle with a gold core surrounded by a dyed silica gain medium created by researchers from purdue, norfolk state and cornell universities, a nanowire on a silver screen by a berkeley group, and a semiconductor layer of 90 nm surrounded by silver pumped electrically by groups at technical university of eindhoven and at arizona state university. while the purdue-norfolk state-cornell team demonstrated the confined plasmonic mode, the berkeley team and the eindhoven-arizona state team demonstrated lasing in the so-called plasmonic gap mode.