Multilevel amplified spontaneous emission in I2

We report the results of a study of amplified spontaneous emission (ASE) in the I2(B→X) system. For many (v′,v″) bands, several J′→J″ transitions contribute to the ASE in a cooperative manner. We present spectroscopic and kinetic data that contrast this cooperative stimulated emission to the emission in previously reported optically pumped lasers. Transitions that involve several cooperatively emitting levels produce efficient conversion of the pump laser to near-infrared output.