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Edison’s Heir: Bob Hall’s Invention Lit Up The Future

Todd Alhart
December 01, 2016
You could argue that the future was born in GE’s labs in 1962. That was the year Robert N. Hall demonstrated the first semiconductor laser, which made possible everything from price code scanners to CD players to the 3D printing of metal parts for jet engines.
It was a heady time for inventors in Niskayuna, New York, the headquarters of GE Global Research. Ivar Giaever’s groundbreaking work on semiconductors in 1960 would eventually earn him a Nobel Prize. Nick Holonyak Jr. invented the first visible LED later in 1962 and also furthered Hall’s work by demonstrating the red-light semiconductor laser. But it was Hall’s work that has perhaps the most visible impact today.

“There is so much in our lives we take for granted today that traces back to Bob’s diode laser,” says Marshall Jones, a principal engineer at GE Global Research and another laser pioneer. “Nobody could get the photons out of the semiconductor crystals,” Holonyak told GE Reports. “But we used a process called stimulated emission to get them out. We knew that in 1962, and Bob is the next person I would have given the Nobel Prize.”

Hall, who obtained 43 patents in his more than 40 years at GE, died on Nov. 7. He was 96.

Robert Hall and Laser Top and above: Robert Hall in his lab. Image credit: GE Global Research

Born in New Haven, Connecticut, Hall became an inventor at an early age and was tapped to attend the California Institute of Technology on a scholarship. After several interruptions in his education, including a stint at GE during World War II, he finally joined the company full time in 1948.

Hall’s early work at GE focused on PIN rectifiers, which are components that control power transmission inside systems. In 1962, he learned about research studying emissions of invisible infrared light from a material called gallium arsenide and realized he could use it to build the first semiconductor laser. “I came up with a structure that we could build and I thought might work and rounded up a group with the necessary talents to tackle the job,” Hall said in an oral history compiled by the Semiconductor Museum.

As with most significant inventions, the laser had many inventors. The first functioning laser had been created at Hughes Research Laboratories, in Malibu, California, in May 1960. A team at IBM was also working on similar semiconductor-based technology in 1962, but Hall’s team beat them by just two weeks.

Hall’s work on lasers was notable because most laser applications, including CD players and price code scanners, use diode lasers derived from the one he created in 1962.

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Lasers are also inside the most advanced 3D printers. GE introduced the first 3D-printed parts on commercial jet engines earlier this year and recently announced plans to build an entire standalone business around additive manufacturing. One of the big reasons additive manufacturing has taken off is because of advances in laser technology. In 3D metal printers, lasers are used to melt or etch layers of metal powders precisely into the shape of a part being made.

When asked how it felt at the time to have made such a big discovery, Hall remarked that he wasn’t sure he would live to celebrate it. His patent was awarded during the Cuban Missile Crisis, with the threat of nuclear war looming. He later worked on silicon photovoltaic technology and invented the “polka-dot solar cell.” He was inducted into the National Inventors Hall of Fame in 1994. Hall retired from GE in 1987.

“Nobody knew how to turn the semiconductor into the laser,” Holonyak, told GE Reports. “We arrived at the answer before anyone else.”

Top image: Robert Hall in his lab. Image credit: GE Global Research