H ELECTRICITY
H01 ELECTRIC ELEMENTS
H01S DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
5/00 Semiconductor lasers
H01S5/30 Structure or shape of the active region; Materials used for the active region
H01S5/34 comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers
H01S5/3401 having no PN junction, e.g. unipolar lasers, intersubband lasers, quantum cascade lasers
H01S5/3402 intersubband lasers, e.g. transitions within the conduction or valence bands