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OT: Physicist Herbert Kroemer, 95, developed laser technology that helps humankind stay connected

(Wash Post Obituaries)

Herbert Kroemer, Nobel winner who developed laser tech, dies at 95

The German-born physicist developed a new kind of semiconductor that became crucial to the development of cellphones, CD players, fiber-optic networks and other touchstones of the Information Age

By Harrison Smith
March 28, 2024 at 7:19 p.m. EDT

Herbert Kroemer in the lab at the University of California at Santa Barbara in 2000. He was awarded a share of the Nobel Prize in physics that year. (Tony Mastres/UC Santa Barbara)

Herbert Kroemer, a Nobel Prize-winning physicist who spearheaded the development of a new kind of semiconductor, leading to Information Age advances at the heart of everything from bar-code scanners, CD players and cellphones to satellite communications and fiber-optic networks, died March 8 at 95.

His death was announced by the University of California at Santa Barbara, where he had been on the faculty for nearly 50 years. A statement from the school’s chancellor, Henry T. Yang, did not say where or how he died but credited Dr. Kroemer with “transforming UC Santa Barbara into a leader in engineering and materials science.”

A German-born researcher with a thick white beard and heavy skepticism of scientific authority, Dr. Kroemer was awarded a share of the Nobel Prize in physics in 2000 for developing semiconductor heterostructures, layered devices that proved foundational to advanced lasers and high-speed transistors.


He shared his half of the prize with the Russian physicist Zhores Alferov, who worked independently but in parallel to develop the devices; the other half went to Jack Kilby, a researcher at Texas Instruments who played a central role in the invention of the integrated circuit, or microchip.

Together, their work “laid a stable foundation for modern information technology,” the Nobel committee said.

Dr. Kroemer launched his scientific career at research labs in West Germany and the United States in the mid-1950s, shortly after the creation of the transistor. The device helped usher in the development of modern electronics, replacing the vacuum tube as an electronic switch and amplifier. Although it was typically built from a single material, usually silicon, Dr. Kroemer proposed creating a faster transistor using a kind of sandwich, or heterostructure, comprising different materials.


In 1963, he applied his heterostructure research to lasers, which had been invented just three years earlier but could work only at low temperatures and for short pulses. Dr. Kroemer developed a way to circumvent those issues, coming up with the basic principle of a device known as the double heterostructure laser, the foundation of the first commercial semiconductor laser.

The devices “are used worldwide in fiber optic networks and enabled the internet, transforming the world,” his colleague John Bowers, director of UC Santa Barbara’s Institute for Energy Efficiency, said in a tribute.

“It was a question of making something possible that without heterostructures simply couldn’t have been done at all,” Dr. Kroemer told the New York Times after winning the Nobel. Without the structures, he added, “there would be no CD players and no CDs,” along with no LED lights and countless other electronic devices.


Dr. Kroemer started out as a theoretical physicist — his first employer, a telecom lab run by the German postal service, insisted that he stay away from research equipment for fear that he would break something — and said that when he developed the idea of the heterostructure laser, he was interested only in the fundamental science behind the concept.

“I really didn’t give a damn about what the uses were,” he told IEEE Spectrum, the flagship magazine of the Institute of Electrical and Electronics Engineers.

But his bosses at Varian Associates, a Silicon Valley research firm, refused to grant him resources to develop the technology, “on the grounds that ‘this device could not possibly have any practical applications,’ ” he recalled in his Nobel lecture. Other researchers, including Alferov, went on to build and refine the first heterostructure lasers.


“It was really a classical case of judging a fundamentally new technology, not by what new applications it might create, but merely by what it might do for already existing applications,” Dr. Kroemer said in his lecture, calling for institutions to focus less on the question of what cutting-edge science might be “good for.”

“The problem is pervasive, as old as technology itself,” he added, noting that the double heterostructure laser “was simply another example in a long chain of similar examples. Nor will it be the last.”

Dr. Kroemer in 2000 at his office at UC Santa Barbara. (Scott Nelson/AFP/Getty Images)
The oldest of three sons, Herbert Kroemer was born in Weimar, Germany, on Aug. 25, 1928. His father was a civil servant, his mother a homemaker. Neither had a high school education, nor did they have much of an interest in science. Still, they sought to encourage Dr. Kroemer’s natural affinity for math, physics and chemistry, including by buying a roughly 20-volume encyclopedia for him.


Looking for additional reading material as a teenager during World War II, Dr. Kroemer went to the library twice a week, making his way through the science section and becoming fascinated by “the realization that from a small set of very fundamental laws one could draw very, very far-reaching conclusions,” as he put it in an oral history.

After graduating from high school in 1947, he enrolled at the University of Jena, where he studied under the physicist Friedrich Hund during the city’s postwar Soviet occupation. As the social climate became increasingly repressive, lecture attendance dwindled; some of his more liberal classmates vanished without explanation.

“You never knew whether they had fled to the West, or had ended up in the German branch of Stalin’s Gulag,” he recalled in an autobiographical essay.

While working for the Siemens company in Berlin during the summer of 1948, Dr. Kroemer decided to resettle in West Germany, getting a seat aboard a return flight of the Berlin airlift. He enrolled at the University of Göttingen and received a PhD in physics in 1952, writing his dissertation on “hot electron” effects in transistors.

Dr. Kroemer conducted some of his early heterostructure research at RCA Laboratories in Princeton, N.J., and settled in California in 1959, joining Varian Associates in Palo Alto. He moved there with his wife, Marie Louise, and their young children, including a 2-year-old daughter, Sabine, who drowned in a pool shortly after they arrived, according to a report in the local Peninsula Times Tribune.

His wife died in 2016. Information on survivors was not immediately available, but they had five children, according to IEEE Spectrum.

Dr. Kroemer joined the faculty at the University of Colorado in 1968 and moved to UC Santa Barbara in 1976, eventually holding joint appointments in the electrical and computer engineering department and the materials department. He received one of Germany’s highest governmental honors, the Grand Cross of the Order of Merit, in 2001, and was awarded the IEEE Medal of Honor the next year.

Dr. Kroemer, left, receives the 2000 Nobel Prize in physics from Swedish King Carl XVI Gustaf in Stockholm. (Henrik Montgomery/Scanpix Sweden/AFP/Getty Images)

After receiving the Nobel Prize, Dr. Kroemer gained a burst of attention, which he largely tried to ignore. “You get a lot of invitations where you know darn well you’re being invited for decoration. Those I mostly turn down,” he told a UC Santa Barbara interviewer. “But there is one kind of invitations where I feel I can give back to society — invitations talking to students,” whom he spoke with at elementary and high schools.

“Society has been good to me,” he said, “and that’s one way I can return that.”

https://www.washingtonpost.com/obituaries/2024/03/28/herbert-kroemer-dead/