The timeline presented here highlights the impact of physical sciences research on communication technology and on the communications industry during the last one hundred and twenty five years. Major milestones in key technologies (electronics and photonics) underlying the communications revolution are transistors, integrated circuits, microprocessors, semiconductor lasers, optical fibers and other light-wave components. Fundamental advances in solid-state physics, materials science and quantum optics during the last sixty years enabled these breakthroughs. These fields have their conceptual roots in electromagnetism and quantum theory and their rapid progress has in turn been dramatically accelerated by the electronics and photonics revolution.

This tight interplay of science and technology, so fruitful for the communications industry, has been the hallmark of Bell Laboratories since their inception. The chart contains hundreds of entries and illustrations highlighting important advances in R&D and products, organized in three eras: the Era of the Electron and Electromagnetism, the Era of Quantum Mechanics and Solid-State Physics, and the Era of Photonics. Selected non-Bell Labs contributions of major scientific or technological impact, including many Nobel Prize winning discoveries and inventions, are also indicated.