(Above: First room temp. CW semiconductor nanolaser with subwavelngth cavity presented at CLEO 2011. From K. Ding et al, CTuG2, CLEO 2011.)

Post by: Jim Van Howe, adapted with permission from Jim's CLEO Blog

The year 2012 marks the impressive 50th anniversary of the invention of the prolific and ubiquitous semiconductor laser. Almost every household in the industrialized world owns at least one--be it in a DVD player (maybe two if it is a Blue-ray), a CD player, an optical mouse--or depend on them indirectly for long-distance phone service, digital cable, or internet access. Besides making telecommunications a practical possibility, semiconductor lasers have paved the way for the development of silicon photonics and will be pivotal in the future of optical information storage and processing. Despite their primary use in mass consumer markets for communications, information processing, mutimedia, and teasing cats (you can even get semiconductor laser pointers with phase masks and lens attachments that project images mice or fish on the floor for your feline to chase), many subfields have profited from the low-cost and small-footprint of these robust laser sources. Take for example the handful of semiconductor sources offered commercially by Thorlabs for optical coherence tomography, or the inexpensive semiconductor laser diode sources used by the Ozcan group for field-portable, ultra-low footprint, holographic microscopes.

There are too many other technologies and subfields to name that have profited as well. All you need to do is think of the numerous optics applications that live at telecom wavelengths near 1300 nm or 1550 nm or DVD player wavelengths, 405 nm and 635 nm. Such lasers offer unbelievable device characteristics at such a low price that researchers and venture capitalists often build their technologies to fit these wavelengths instead of the other way around.

Amnon Yariv and Pochi Yeh write in their 2007 edition of the book Photonics that,

"The semiconductor laser invented in 1961 is the first laser to make the transition from a research topic and specialized applications to the mass consumer market...It is by economic standards and the degree of its applications, the most important of all lasers."

To celebrate the most important laser of lasers, CLEO will be hosting a special symposium with talks from pioneers of semiconductor laser technology. The list of speakers and subjects has been well-crafted to paint not only a historical picture, but to address current research and trends on this ever-evolving technology.

From a fundamentals perspective, Russel Dupuis from Georgia Tech will be talking about device materials. Nobel Laureate Herbert Kroemer of University of California Santa Barbara will discuss the double heterostructure which is still the basic framework for almost all semiconductor light sources and solar cells and which without there would be no continuous wave (CW) lasing in semiconductor devices at room temperature. To this end, Morton Panish, formerly of Bell Laboratories, will describe the development of the first room temperature semiconductor laser.

(Above: Evolution of threshold current. From Nobel Laureate Z. Alferov, IEEE J. Sel. Top. Quant. Elec. 6, 832, 2000.)

Charles Henry, formerly of Bell Laboratories, will discuss the quantum well structure which was pivotal in reducing active layer thickness and therefore significantly reducing threshold current, see the figure above. Yasuhiko Arakawa from the University of Tokyo will discuss quantum dot lasers which reduced threshold densities even further and remains a developing area of semiconductor laser physics research.

On the more practical side, Jack Jewell, of Green VCSEL will discuss the vertical cavity surface emitting laser (VCSEL) which among other important device attributes may be the best laser for high-yield production. VCSELs are grown, processed, and tested in wafer-form allowing parallel fabrication and testing, minimizing labor and maximizing yield. They also take up less space on a wafer- about three times less than edge emitters of similar power and can be made in 2-D arrays. Jewell will likely discuss the benefits of lower power consumption of VCSELs for use in short-reach, high-speed networks. My understanding is that the "green" in "Green VCSEL" refers to environmental considerations not wavelength.

There will also be talks discussing the semiconductor laser's role in telecommunications, quantum cascade lasers, integrated and hybrid optical circuits, high-power devices, as well progress in nanolaser structures with subwavelength volume (see the figure at the top).

Whether to learn the history, fundamental principles, pay homage to the pioneers, or to learn new trends, be sure to mark your calendar for the 50th Anniversary of the Semiconductor Laser symposium to celebrate "the most important of all lasers."

 Jim Van Howe (jamesvanhowe@augustana.edu) is an assistant professor of physics at Augustana Collage in Rock Island, Ill., U.S.A.

Nobel Laureates, Optics History, OSA History

By John N. Howard, OPN Contributing Editor

The May issue of Optics & Photonics News includes a profile that traces the fascinating life of Art Schawlow, Nobel laureate and former OSA president, as well as a history of the journal Applied Optics and how it came to publish some of the seminal papers on early laser development. This post explores where the two stories intersect...

In 1959 the Board of Directors of OSA decided that OSA should have a full-time executive secretary working in an executive office located in Washington, D.C. Professor Mary Warga of the University of Pittsburgh was recruited to fill that role. She was nearing retirement age from the physics department at Pittsburgh, and she looked forward with much enthusiasm to her new duties at OSA. A year later, in the fall of 1960, the OSA Board also voted to launch a new OSA journal, Applied Optics. The hope was that it would capture some of the interdisciplinary papers related to optics that did not seem to be flowing to the Journal of the Optical Society of America (JOSA).

Mary Warga introduced a new, one-page column, “From the Executive Office,” in JOSA, and she also began a program of visiting research centers that were oriented toward optics, to inform those researchers about OSA and to try to persuade those workers to join OSA and submit their research papers to JOSA and AO. One of the laboratories she visited in her first year at OSA was Bell Telephone Laboratories, which included a very distinguished research group located in Murrey Hill, N.J., U.S.A. When she visited there in 1960, her host was a bright young spectroscopist with a strong background in optics. His name was Arthur Schawlow.

Arthur Schawlow was born in suburban New York in 1921. His father was an emigrant from Latvia to America, and his mother was Canadian. When Arthur was three years old, the family moved to Toronto, where Arthur attended public schools, and then (at age 16) the University of Toronto. He originally thought he would be an engineer, but then he settled into physics. Presumably, he took the optics course offered by Professor W. E.K. Middleton. (Middleton was very active in OSA, and had served on the OSA Board of Directors. In 1933, Middleton had been the Ives Medalist of OSA.) After graduating with a bachelor’s degree from Toronto; Schawlow remained there for his graduate study. His thesis advisor was Malcolm Crawford, a spectroscopist.

Following his Ph.D. at Toronto, Schawlow served a post-doctoral fellowship at Columbia University, working under Charles Townes. He then joined Bell Labs in 1951.

So, when Mary Warga visited Bell Labs in 1960; Arthur Schawlow was a kind, sympathetic host. He immediately joined OSA and promised to urge several of his colleagues also to join. Futhermore, he promised Mary Warga that his group would submit a paper for the inaugural issue of Applied Optics. Mary returned to Washington following her visit to Murray Hill very pleased with the success of her visit. Schawlow became active in OSA and later served as president of OSA. He also went on to share a Nobel Prize in Physics in 1981 with Nicolaas Bloembergen. Schawlow is the only Nobel laureate to have also served as OSA president.  

Nobel Laureates, Optics History, OSA History, Physics History, Profiles Arthur Schawlow, Mary Warga, OSA, the Optical Society, physics history, optics history, optics, Optics & Photonics News, John N. Howard