sentences:  The invention of the first room-temperature diode laser in the Soviet Union occurred during a climate of intense Cold War competition and secrecy, albeit with sporadic scientific contacts at international conferences and during politically sanctioned international visits.The question of primacy of the invention was debated over the years.Today, however, semiconductor laser scientists agree that the key design concept that enabled the room-temperature diode laser, namely the double-heterostructure design, was invented in the Soviet Union in 1964 by Rudolf F. Kazarinov and Zhores Alferov, as recorded in a Russian patent application filed that year.