Principles of squeezed state generation in semiconductor lasers and light emitting diodes (LEDs) are discussed. Shot noise suppression in electron transport in macroscopic conductors is ultimately due to Pauli exclusion principle for fermion particles, electrons. Shot noise suppression in electron injection in macroscopic pn junctions originates from collective Coulomb blockade effect for changed particles, electrons. Regulated single photon generation in mesoscopic pn junctions is also discussed. © 1997 Elsevier Science S.A.