Research and Innovation

From the 1920s, AT&T became renowned for invention and innovation, not just in the field of telephony, but also in the fields of sound recording and electronic engineering. In 1924, it pioneered commercial facsimile services by developing the technology for “telephotography,” the transmission of photographs by telephone line. Photographs were successfully sent from Chicago and Cleveland to New York. This system became widely used by the newspaper industry. The next step after the transmission of still images by phone was the transmission of moving images. In 1927, before television broadcasting existed, Bell System demonstrated long-distance television transmission by sending live images of Herbert Hoover, the secretary of commerce, from Washington, D.C., to New York. Bell System had introduced the concept of electrical sound recording in 1915, by demonstrating that the carbon microphone used as the telephone mouthpiece was equally suitable for capturing sound for phonographic reproduction. In 1931, engineers at Bell Laboratories developed an improved technique for “cutting” gramophone records, whereby the stylus vibrated up and down rather than from side to side. They went on to develop a method for stereophonic recording in 1933 that eventually became standard in the 1940s, although the first stereo experiments had been carried out in Britain two years earlier.

Perhaps the most significant single invention ever to emerge from Bell Laboratories was the transistor, which began the micro-electronics revolution. This stemmed from wartime research into the properties of semiconducting crystals, such as silicon and germanium, in relation to radar. In December 1947, three Bell research engineers—John Bardeen, William Shockley, and Walter Brattain—developed the n-type semiconductor diode. The three received the 1956 Nobel Prize in physics for their work on the transistor. Further research into silicon revealed that sunlight caused a release of energy from silicon that could be converted to electric current. The first solar cell, or battery, was created at Bell Laboratories in 1954. The physicist Arthur Leonard Schawlow joined the research team at Bell Laboratories in 1951. Schawlow developed existing ideas on the laser (light amplification by stimulated emission of radiation), an optical version of the maser (microwave amplification by stimulated emission of radiation). In 1961, the first continuous-beam laser was made at Bell Laboratories. It was the combination of the laser and optical fiber cables that enabled telephone service capacity to be increased in the 1980s.

AT&T became involved in research into computer operating systems and computer languages from its perspective as a user of computers for the control of switching systems and call routing. The nature of its computer use meant that it took an early interest in the development of systems that were interoperable and accommodated multiple users. In 1969, Bell Laboratories developed the UNIX operating system. In the early 1970s, the Bell researchers refined the language on which UNIX was based to create C, a high-level, general-purpose computer language. This made UNIX compatible with virtually any of the existing minicomputers. UNIX became widely used on networked computers. By the early 1980s, C was becoming restrictive for more demanding computer applications. In 1983, a Bell Laboratories researcher, Bjarne Stroustrup, added the principles of object-oriented programming to C to create C++, which has become one of the most widely used programming languages.