By Neal Singer
The first steps toward reducing the size and enhancing the functionality of devices in the terahertz (THz) frequency spectrum have been taken by Sandia researchers. By combining a detector and laser on the same chip to make a compact receiver, the researchers rendered unnecessary the precision alignment of optical components formerly needed to couple the laser to the detector.
“Similar to moving from discrete transistors to integrated chips in the microwave world and moving from optical breadboards to photonic integrated circuits in the visible/infrared world, this work represents the first steps toward reduction in size and enhanced functionality in the THz frequency spectrum,” Sandia lead researcher Mike Wanke says.
The ridge waveguide of a THz quantum-cascade laser (QCL) is seen extending into and out of this image. A Schottky diode detector is placed into the laser core through a small opening in the top metal contact. A coplanar waveguide connected to the diode carries signals off the chip at the difference frequency between a QCL mode (seen leaving the laser in green) and an external signal (seen entering the laser in blue).
The new solid-state system puts to use the so-called “neglected middle child” frequency range between the microwave and infrared parts of the electromagnetic spectrum.
Terahertz radiation is of interest because some frequencies can be used to “see through” certain materials. Potentially they could be used in dental or skin cancer imaging to distinguish different tissue types. They also permit improved nondestructive testing of materials during production monitoring. Other frequencies could be used to penetrate clothing and possibly identify chemical/biological weapons and narcotics.
Since the demonstration of semiconductor THz quantum cascade lasers (QCLs) in 2002, some researchers have speculated that these devices could offer unprecedented advantages in technologies used for security, communications, radar, chemical spectroscopy, radioastronomy, and medical diagnostics.
Until now, however, sensitive coherent transceiver systems could only be assembled from a collection of discrete and often very large components.
The work, described in the June 27, 2010, issue of Nature Photonics, represents the first successful monolithic integration of a THz quantum-cascade laser and diode mixer to form a simple, but generically useful terahertz photonic integrated circuit — a microelectronic terahertz transceiver (transmitter/receiver).
With investment from Sandia’s Laboratory Directed Research and Development (LDRD) program, the lab focused on the integration of THz QCLs with sensitive, high-speed THz Schottky diode detectors, resulting in a compact, reliable solid-state platform. The transceiver embeds a small Schottky diode into the ridge waveguide cavity of a QCL, so that local-oscillator power is directly supplied to the cathode of the diode from the QCL internal fields, with no optical coupling path.
The Sandia semiconductor THz development team, headed by Mike Wanke, also included Erik Young, Christopher Nordquist, Michael Cich, Charles Fuller, John Reno, Mark Lee — all of Sandia — and Albert Grine of LMATA Government Services in Albuquerque. Young recently joined Philips Lumileds in San Jose, Calif.
The paper is available online (abstracts are available to everyone, full text only to subscribers) at http://dx.doi.org/10.1038/NPHOTON.2010.137. -- Neal Singer
By Neal Singer
Sandia researchers — competing in an international pool that includes universities, start ups, large corporations, and government labs — received four R&D 100 Awards this year, and played a role in at least one more.
R&D Magazine presents the awards each year to researchers whom its magazine editors and independent judging panels determine have developed the year’s 100 most outstanding advances in applied technologies.
The awards, with their focus on practical effects rather than pure research, reward entrants on their products’ design, development, testing, and production.
Winners are expected to participate in a formal awards banquet at the Renaissance Orlando Hotel in Florida on Nov. 11.
DOE Secretary Steven Chu said, “The large number of winners from the Department of Energy’s national labs every year is a clear sign that our labs are doing some of the most innovative research in the world. This work benefits us all by enhancing America’s competitiveness, ensuring our security, providing new energy solutions, and expanding the frontiers of our knowledge. Our national labs are truly national treasures, and it is wonderful to see their work recognized once again.
The four Sandia award winners are:
1. “Multifunctional Optical Coatings by Rapid Self-Assembly.” The technique inexpensively forms film-like coatings already widely used in consumer electronics, semiconductor devices, and high-performance glass and ceramics. Rather than requiring high temperatures and/or the considerable vacuum of current commercial operations, the Sandia method disperses commercially available polymers by inserting them in common solvents under ambient conditions and then uses simple spin, dip, or spray techniques to coat surfaces. Evaporation of the solvents induces the polymers to self-assemble into multifunctional nanoparticles as well as films with tailored optical properties and a nanostructured surface. Because the process is compatible with conventional spray processing, it can be applied directly to the coating of large or complex parts, which current commercial methods are less able to do. The work was led by Sandian Hongyou Fan (1815) and his group as a joint entry with Lockheed Martin. Researchers from University of New Mexico also participated.
Sandia: Hongyou Fan (PI, 1815); Huimeng Wu (postdoc, 1815); UNM: Zaicheng Sun, Feng Bai; Davidson College: Dan Boye (sabbatical professor in Hongyou Fan’s group); Lockheed Martin: Earl Stromberg (Lockheed Martin, Aeronautics Company)
2. “Acoustic Wave Biosensor for Rapid Point-of-Care Medical Diagnosis.” The device, a joint effort of Sandia and the University of New Mexico Health Sciences Center, is essentially a handheld, battery-powered, portable detection system capable of identifying a wide range of medically relevant pathogens from their biomolecular signatures. Detection can occur within minutes, not hours, at the point of care, whether that care is in a physician’s office, a hospital bed, or at the scene of a biodefense or biomedical emergency. According to the researchers, “The Acoustic Wave Biosensor provides fast, low-cost diagnostic results with as good or better sensitivity than traditional techniques.” The device’s sensor array works like a miniature analytical balance, weighing the amount of pathogen that binds to its surfaces. The pathogen-bound sensor acts like a spring with a small weight bouncing at one end. As more pathogens stick to the surface, the weight on the spring increases, causing the spring’s bouncing speed to decrease by a measurable amount. The sensors detect minute weight differences by this method. A variety of sticky substances (ligands) attach to different pathogens. Surface tension draws the sample over the sensor, so no pumps or valves are required. This makes the sensors smaller, more reliable, and less expensive to manufacture, and extends the operating time of the rechargeable batteries. System control, data analysis, and reporting are performed by a personal digital assistant.
Sandia: Susan Brozik, Darren Branch, Thayne Edwards, and David Wheeler (all 1714); UNM: Richard Larson, Brian Hjelle, David Brown, Pam Hall, and Marco Bisoffi
3. “CANARY: Event Detection Software.” How does a country whose water supply is as dispersed as that of the US act to rapidly and accurately detect contamination of any of it, whether due to natural causes or terrorist activities? Sandia researchers, led by Sean McKenna (6731), working with the US Environmental Protection Agency’s National Homeland Security Research Center, have developed software that enables immediate contaminant detection by continuously analyzing signals from networked sensors for unusual responses. The software is designed to be compatible with sensor technologies and information technology programs existing at most water utilities, and it can be easily modified by the end-user for specific applications and for utility-specific customization. But this isn’t just a war-and-disease prevention program — several utilities have reported that using the software has enhanced the day-to-day water quality management within their distribution networks. Sean says, “I think this project has been a great example of staff with different backgrounds and expertise coming together from across the Lab (three divisions and four centers) to solve a security problem that is making an impact both nationally and internationally. For example, Singapore has been running CANARY on its national drinking water system since July of 2009.”
From Sandia: Sean McKenna (6731); David Hart (6731); Katherine (Kate) Klise (6731); Eric Vugrin (6371); Mark Koch (5433); Shawn Martin (1415); Bill Hart (1415); US EPA National Homeland Security Research Center: Regan Murray, Terra Haxton, John Hall; EPA Office of Water: Katie Umberg
4. “Micro Power Source.” You’ve accepted that batteries run out of power and that newer batteries are rechargeable in wall electric sockets. But why should you go through all that? Why not a battery covered by a thin photovoltaic film? Just like on rooftops, the photovoltaic surface could harvest sunlight and turn it into electricity, recharging the battery in an ongoing process. This work, a joint effort with Pacific Northwest National Laboratory and Front Edge Technology Inc. in Baldwin Park, Calif., was originally part of a Defense Advanced Research Projects Agency program, but commercial applications were “evident from the start,” the researchers wrote. The most likely immediate applications of the durable batteries are self-powered environmental sensors, self-powered tags for material tracking, and self-powered “smart” cards to enhance user features and security. The key feature for the micropower source is a volume of only one microliter, yet a high peak-power density greater than 1,000 watts per liter. This makes the device useful for powering wireless microsystems that sense, record, transmit, and/or actuate. The photovoltaic battery stack itself is only five millimeters in diameter and approximately 50 micrometers thick. (A human hair is approximately 70 micrometers thick.)
Sandia team includes Todd Bauer (1746); David Stein (1726); Carlos Sanchez (1746); Rob Jarecki (1746); Randy Shul (1746); Darlene Udoni (1726); Doug Greth (LMATA); and Chris Ford (LMATA); with assistance from the MESAFab staff. LMATA Government Services, a small business joint venture created by L&M Technologies, Inc., and ATA Services, Inc., is dedicated to the recruitment and staffing of professional, support, and administrative personnel.
5. Another Sandia effort aided researchers at Los Alamos National Laboratories in developing another winning effort: “The Solution Deposition Planarization.”
-- Neal Singer
W.J. “Jack” Howard’s dedication to his life’s work becomes obvious even after a short visit with him, in the way he talks about his 36 years at Sandia and by glancing at the book sitting on the end table near the recliner where he sits. It’s Brotherhood of the Bomb by Gregg Herken, about the lives of Robert Oppenheimer, Ernest Lawrence, and Edward Teller.
The former Sandia executive VP — who was a valued national adviser on US nuclear policy and an advocate for nuclear weapons safety and control — has become the third Sandian to be inducted into the Labs’ Hall of Fame. The honor recognizes former employees who made pivotal contributions that have significantly enhanced Sandia.
During his career, Howard, 87, of Albuquerque, was responsible for the early recognition that US nuclear weapons needed built-in controls to prevent unauthorized or inadvertent arming. He also participated in early nuclear weapons tests, established the first independent nuclear safety assessment group at Sandia and was the first director of Sandia’s site in Livermore, Calif.
At a ceremony June 30 attended by dozens of Howard’s friends and former colleagues, Executive VP Al Romig said the honor was “reserved for people with a tremendous enduring impact” on the Labs.
“Jack’s contributions to shaping the Laboratory as we know it today are immeasurable,” new Labs Director Paul Hommert said. “He is well qualified to join the ranks of those already in our Hall of Fame and stands as an exceptional example for all Sandians who will follow.”
Outgoing Labs Director Tom Hunter agrees, adding that, “I would describe Jack as one who laid the foundations not just for our nuclear weapons program but also for our values of national service and excellence.”
Jack, who was nominated for the Hall of Fame by Div. 1000 VP Steve Rottler, is the third inductee after former VP Glenn Fowler and former Executive VP Robert Henderson.
As a bronze bas-relief plaque of Jack’s likeness was unveiled at the ceremony, he smiled and clasped his hands together in a seeming gesture of thanks. The plaque will hang alongside the two others in the entrance lobby of Bldg. 800.
Colleagues say Jack, who retired in 1982 after serving nine years as executive VP, was a key executive in the Labs’ 60-year history and an excellent steward of Sandia. They describe him as a man of few carefully selected words who could motivate and mentor employees to make sure jobs got done right.
“He was a forward-looking person in a very pragmatic sense,” says Orval Jones, a former executive VP at Sandia who first worked with Jack in 1973. “Jack saw the need to really aggressively pursue nuclear weapons safety.”
Jack was born in Kimball, Neb., in 1922 and came to New Mexico with his family when he was a junior in high school.
Prior to joining Sandia, Jack graduated with a degree in mechanical engineering from what is now New Mexico State University and served in World War II. While he served at Clark Air Force Base in the Philippines, Jack described how he survived a mountain airplane crash that killed the pilot by hiking for six days along a stream with a shattered kneecap until he found help.
In 1946, Jack joined the Z Division of Los Alamos National Laboratory, which is now Sandia Labs, when he was in his mid-20s. Jack recalled in a recent interview shooting rattle snakes and eating lunch outdoors next to a bubbling spring in Coyote Canyon in those early days.
“The mission I had at the time was firing 10,000 pounds of usual explosives. I fired one one day and it blew out some big store windows in Albuquerque. There had been a [temperature] inversion,” he says. After the incident, “we got our own instrument for measuring the inversion of the air. If there was an inversion, we didn’t shoot that day,” he says.
Over the years, Jack racked up a notable list of achievements in weapons work at Sandia. He directed the ordnance engineering design and development of the first Polaris missile warhead, which led to Sandia receiving a Certificate of Merit from the US Navy. And he was the motivating force behind the concept of the nuclear warhead and delivery system, which led to what is known as the “Davy Crockett” infantry weapon system. The system was designed for use by the US infantry in Europe against Soviet troops during the Cold War.
Safety and use control
Safety and control of nuclear weapons also mattered to Jack. To prevent unauthorized detonation of nuclear weapons, Jack recognized early the need for built-in control of the arming sequence of US nuclear weapons. He participated in preliminary design of the Permissive Action Link (PAL) system that resulted. The PAL system is a coded switch inside a nuclear weapon that blocks the arming signal and requires an order from the president to pass through the proper channels to the officer-in-charge, who then would enter the code.
“All I did was ask the question,” Jack says, when asked about his role in PAL.
Jack was instrumental in establishing an independent nuclear safety assessment group at Sandia in 1969. The group oversaw an ongoing safety review of existing nuclear weapons, developed new safety technologies, and developed techniques for evaluating evolving safety concepts.
Perhaps Jack’s most visible achievement to the public is Sandia/California’s site in Livermore. Jack was assigned in 1956 to inaugurate the new laboratory to provide ordnance engineering support to what is now known as Lawrence Livermore National Laboratory. Jack recalled initially being located in dilapidated barracks, but a year later his employees moved to a new building.
Since Sandia/California was new, it had to be bold and innovative. But Jack says he was directed by a superior to “sing from the same sheet of music” with colleagues at Lawrence Livermore. “I said, ‘Yes, sir, but you’ve got to recognize there’s a heavy metal group just across the street,’” he says. Sandia/California has grown from that small initial group to about 1,100 employees today.
Jack also was appointed to national positions, including serving as a delegate to the Strategic Arms Limitation Talks in Geneva, Switzerland, in 1976. He became a valued adviser in formulating and guiding the implementation of national nuclear policy.
From 1963-1966, he served as assistant to the secretary of defense for atomic energy at DoD and was the chairman of the Atomic Energy Commission’s Military Liaison Committee. During this time, he assisted with ballistics support to locate a missing nuclear weapon near Palomares, Spain, after the collision of a B-52 and tanker aircraft during a refueling operation.
Defense Secretary Robert McNamara awarded Jack the DoD Medal for Distinguished Public Service for his work. -- Heather Clark