When Silke Pflueger attended her first ICALEO® in San Diego in the 1990s, she was a bit overwhelmed by having to give a talk about her work.
“The first presentation is scary,” she recalls. But that initial involvement has led Pflueger all the way to serving as congress general chair of ICALEO, the International Congress on Applications of Lasers & Electro-Optics, to be held Oct. 18-22 at the Sheraton Atlanta in the heart of the city. Now she is overseeing a team of conference chairs for the 2015 gathering, including:
Laser Materials Processing Conference: Christoph Leyens, Fraunhofer IWS
Nanomanufacturing Conference: Yongfeng Lu, University of Nebraska-Lincoln
Business Forum & Panel Discussion: Klaus Loeffler, TRUMPF, and Bo Gu, BOS Photonics
“With over 200 presentations and posters on the latest in laser research, strengthened by the peer-review process introduced last year, ICALEO will provide another outstanding opportunity to learn about advances in laser material processing,” Pflueger notes in her welcome message for the ICALEO advance program (available online at www.icaleo.org). Continue reading →
Photo of Charles Townes with a ruby maser amplifier courtesy of Bell Labs
In his 1999 book How the Laser Happened, the late Charles Hard Townes explained that, “Once invented, lasers found a myriad of uses” and noted that they had advanced to the point that “the smallest lasers are so tiny one cannot see them without a microscope.”
A far cry from the heady days of the 1950s. Imagine Townes conceiving and building a maser (microwave amplification by stimulated emission of radiation) at Columbia University before the heated race to pursue a patent for an optical maser — the laser. Imagine the fevered discussion in the scientific community as Townes and Arthur Schawlow at Bell Labs beat Gordon Gould and Technical Research Group to that first laser patent — two months before Theodore Maiman built his ruby laser for Hughes Research Laboratories in Malibu, CA, in 1960.
Patent, filed in 1958
Townes — who famously conceived the idea for the laser while sitting on a park bench in Washington, DC in 1951 — worked until his 99th year, maintaining an office at the physics department of the University of California, Berkeley. The campus honored him with a birthday celebration July 28, 2014; he passed away in January 2015. Continue reading →
Researchers at Arizona State University have created white laser light with an array of semiconductor lasers in a compact arrangement. The project helps pave the way toward better lighting and light-based wireless communication, as white lasers are more luminous and energy efficient than LEDs.
This schematic illustrates the novel nanosheet with three parallel segments created by the researchers, each supporting laser action in one of three elementary colors. The device is capable of lasing in any visible color, completely tunable from red, green to blue, or any color in between. When the total field is collected, a white color emerges. Photo by: ASU/Nature Nanotechnology
ASU researchers created a novel nanosheet — a thin layer of semiconductor that measures roughly one-fifth of the thickness of human hair in size and roughly one-thousandth the thickness of human hair — with three parallel segments, each supporting laser action in one of three elementary colors. The device is capable of lasing in any visible color, completely tunable from red, green to blue or any color in between. When the total field is collected, a white color emerges.
The advance puts lasers a step closer to being a mainstream light source and potential replacement or alternative to light emitting diodes. Lasers are brighter, more energy efficient, and can potentially provide more accurate and vivid colors for displays like computer screens and televisions. Ning’s group has already shown that their structures could cover as much as 70 percent more colors than the current display industry standard.
Another important application could be in visible light communication in which the same room lighting systems could be used for illumination and communication. The technology under development is called Li-Fi for light-based wireless communication, as opposed to the more prevailing Wi-Fi using radio waves. Li-Fi could be more than 10 times faster than current Wi-Fi, and white laser Li-Fi could be 10 to 100 times faster than LED based Li-Fi under development.
“The concept of white lasers first seems counterintuitive because the light from a typical laser contains exactly one color, a specific wavelength of the electromagnetic spectrum, rather than a broad-range of different wavelengths,” Ning explained. “White light is typically viewed as a complete mixture of all of the wavelengths of the visible spectrum.”
Sandia National Labs in 2011 produced high-quality white light from four large lasers. The researchers showed that the human eye is as comfortable with white light generated by diode lasers as with that produced by LEDs, inspiring others to advance the technology.
But “those independent lasers cannot be used for room lighting or in displays,” Ning said. “A single tiny piece of semiconductor material emitting laser light in all colors or in white is desired.”
Semiconductors, usually a solid chemical element or compound arranged into crystals, are widely used for computer chips or for light generation in telecommunication systems. They are used to make lasers and LEDs because they can emit light of a specific color when a voltage is applied to them. The most preferred light emitting material for semiconductors is indium gallium nitride, though other materials such as cadmium sulfide and cadmium selenide also are used for emitting visible colors.
The main challenge lies in the way light emitting semiconductor materials are grown and how they emit light of different colors. Typically a semiconductor emits light of a single color — blue, green or red — that is determined by a unique atomic structure and energy bandgap.
The “lattice constant” represents the distance between the atoms. To produce all possible wavelengths in the visible spectral range you need several semiconductors of different lattice constants and energy bandgaps.
“Our goal is to achieve a single semiconductor piece capable of laser operation in the three fundamental lasing colors. The piece should be small enough so that people can perceive only one overall mixed color instead of three individual colors,” said Fan. — Sharon Keeler, chief media officer, Ira A. Fulton Schools of Engineering. Read more about the research here.
Not resting on the laurels of its flagship conference, the Laser Institute of America instituted a peer-review process for its 33rd International Congress on Applications of Lasers & Electro-Optics (ICALEO®), held Oct. 19-23 in San Diego.
For the first time, ICALEO featured presentations given even more rigorous analysis than previous events; 56 of the 61 papers submitted for peer review were accepted. “It was quite a bit of a challenge” reviewing abstracts, said returning Congress General Chair Stefan Kaierle of Laser Zentrum Hannover. “We believe it was necessary… to change the way we present our work and especially to improve the quality.” At least two people reviewed each paper in the double-blind process. About 35 to 40 papers will be published in a special edition of the Journal of Laser Applications® (JLA), he said.
For the first time, presentations at the Laser Institute of America’s 33rd International Congress on Applications of Lasers & Electro-Optics (ICALEO®) will undergo a peer-review process that will bring even more scholarly rigor to the cutting-edge research presented at the conference.
“It’s my second year as general chair, but there have been a few more years of my being a member of the conference chairs,” says returning Congress General Chair Stefan Kaierle of Laser Zentrum Hannover. “The lessons I have learned have grown during that period, and one of my main findings is that we need a good team, composed out of the conference chairs, the advisory committees and the staff from the LIA in order to set up a good conference. Only if we all work closely together with intense information exchange, are we able to find the best solutions for changes to incorporate or just to decide on how successful parts of the conference can be further improved or maintained.” Continue reading →
