1962 · Semiconductor Laser Diode · Work 839 of 1,871
A research laboratory in Schenectady in the evening, a tall clear glass vacuum flask filled with liquid nitrogen with white vapour spilling over its rim, inside it on a copper rod a tiny brass mount holding a crystal chip one third of a millimetre across, brass supports and stand arms around the flask, beside it an oscilloscope with a single sharp green spike on its round screen, a hand in a rolled-up white shirt sleeve holding a short black infrared viewing tube aimed at the flask, subdued ceiling light, the vapour catching the light.
What it was used for
The injection laser is a gallium arsenide semiconductor diode that emits coherent light when current flows through its p-n junction. Robert Hall's group at the General Electric Research Laboratory in Schenectady polished two opposing faces of a roughly cubic diode crystal 0.44 mm on a side and so obtained the optical cavity; the report appeared in Physical Review Letters on 1 November 1962. In 1962 the device was usable only in the laboratory: all four of them ran at 77 K in liquid nitrogen and in pulsed mode, with pulses of about 100 ns at about 100 Hz.
What was new
What was new was not light from GaAs diodes - strong infrared emission had already been reported at conferences in the summer of 1962 - but the cavity that turned luminescence into laser light. Four groups got there within about five weeks: General Electric Schenectady (Hall), IBM (Nathan), General Electric Syracuse (Holonyak, visible red near 660 nm) and MIT Lincoln Laboratory (Quist, Rediker); three of the devices emitted near 840 nm. GE and IBM were published simultaneously on 1 November 1962, but the GE manuscript had been received 11 days earlier and showed a complete laser structure with polished end faces, whereas IBM reported line narrowing in an etched diode; GE also filed its patent application 11 days before IBM. Room-temperature continuous-wave operation took until 1970.
What the sources leave open: Hall's crystal dimension and the publication date from the American Physical Society; the operating conditions 77 K, 100 ns, 100 Hz, the wavelengths and the 1970 continuous-wave result with a 1600 A/cm² threshold from Marshall Nathan's own account at Optica. Both name four laboratories, Nathan within five weeks, the IEEE milestone proposal within "roughly one month". The APS names Hall as first, the IEEE proposal all four as independent first demonstrations; only ETHW mentions the patent lead.