New research on perovskite-based solar cells pioneered in the U.K. suggests that they can double up as a laser as well as photovoltaic device. By sandwiching a thin layer of the lead halide perovskite between two mirrors, the Univ. of Cambridge team produced an optically driven laser which proves these cells “show very efficient luminescence”, with up to 70% of absorbed light re-emitted.
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Associated with unhappy visits to the dentist, “cavity” means something else in the science of optics. An arrangement of mirrors that allows beams of light to circulate in closed paths, or cavities, help us build laser and optical fibers. Now, a research team pushed the concept further by developing an optical “nanocavity” that boosts the amount of light that ultrathin semiconductors absorb.
Photonic devices are typically built using customized methods that make them difficult and expensive to manufacture. But at the Optical Fiber Communication Conference and Exposition next month, two new devices, a modulator and a tunable filter, are being presented that are not only as energy-efficient as some of the best devices around, but were built using standard CMOS process technology.
One of the main challenges for engineers trying to make practical terahertz wave devices is making the lasers powerful and compact enough to be useful. Engineers in the U.K. have reported their new quantum cascade terahertz laser exceeds 1 W output power. The new record more than doubles landmarks set by the Massachusetts Institute of Technology and subsequently by a team from Vienna last year.
Scientists at the Univ. of Strathclyde, U.K., have successfully demonstrated two notable high-power laser research developments: the first ever tunable diamond Raman laser and the first continuous-wave (CW) laser. Both lasers use synthetic diamond material made by California’s Element Six. The breakthrough is a significant achievement in solid-state laser engineering.
The most efficient way to convert light into different wavelengths for use in spectroscopy or laser applications is to use nonlinear optical crystals, but these tend to suffer crystal damage at high laser intensities. Oleg Louchev of the RIKEN Center in Japan and colleagues have discovered that such crystal damage arises from small localized temperature rises due to photon absorption and electric field effects within the crystal.
It's hard to study individual molecules in a gas because they tumble around chaotically and never sit still. Researchers in California overcame this challenge by using a laser to point them in the same general direction, like compass needles responding to a magnet, so they could be more easily studied with an x-ray laser. It’s a key step toward producing movies that show how a single molecule changes during a chemical reaction.
Ultra-short laser pulses provide a fast and precise way of processing a wide range of materials without excessive heat input. Scientists from Bosch, TRUMPF, Jena Univ. and Fraunhofer Institute in Germany have turned the ultra-short pulse laser into an effective series-production tool. This type of laser can remove, or ablate, tiny areas measuring just a few nanometers.
Photolithography uses light beams to design thin geometric patterns on the substrates of semiconductors used in microelectronic devices, but the phenomenon of light diffraction does not permit highly accurate patterns. A new quantum lithography protocol from a scientist in Russia now makes it possible to improve the accuracy of photolithography by addressing its physical limitations.
Researchers in Spain, working with the firm Luz WaveLabs, are developing an innovative terahertz generator that improves signal quality by one million times as compared to the best device of this kind currently on the market. They have achieved this level of quality through the use, in part, of a specialized optical frequency comb and modifications to the laser source.
In the early morning hours of Oct. 18, NASA’s Lunar Laser Communication Demonstration made history, transmitting data from lunar orbit to Earth at a rate of 622Mbps. That download rate is more than six times faster than previous state-of-the-art radio systems flown to the moon.
The direct emission of terahertz radiation would be useful in science, but no laser has yet been developed which can provide it. A team headed of researchers have now demonstrated that graphene meets an important condition for use in novel lasers for terahertz pulses with long wavelengths: It permits population inversion, a key prerequisite for stimulated radiation emission.
Researchers have demonstrated a new method for measuring laser power by reflecting the light off a mirrored scale, which behaves as a force detector. Although it may sound odd, the technique is promising as a simpler, faster, less costly and more portable alternative to conventional methods of calibrating high-power lasers used in manufacturing, the military and research.
Terahertz radiation is gaining attention due to its many applications. Traditional methods of generating terahertz radiation, however, usually involve large and expensive instruments, some of which also require cryogenic cooling. A compact terahertz source operating at room temperature with high power has been a dream device in the terahertz community for decades. A team from Northwestern Univ. has now brought this dream closer to reality.
Measuring the band offset faced by electrons jumping from one material to another is a key component of a nanoscale design process because it guides redesign and prototyping. Current methods don’t work on the nanoscale, however. Using laser-induced current in a nanowire device and its dependence on the wavelength of the laser, a team at Drexel Univ. devised a new method to derive the band offset.
When NASA’s Lunar Laser Communication Demonstration (LLCD) begins operation aboard the Lunar Atmosphere and Dust Environment Explorer (LADEE), it will attempt to show two-way laser communication beyond Earth is possible, expanding the possibility of transmitting huge amounts of data. This new ability could one day allow for 3-D high-definition video transmissions in deep space to become routine.
Standard drug-testing methods have shortcomings. Animal testing is expensive and unreliable, and the static environment of cells and cultures don’t mimic the behavior of the entire organism. An interdisciplinary research team at Lehigh Univ. is using microscopy and optical tweezers to develop a new finger-sized chip that can study the activities of cells at the nanoscale, possibly offering an alternative to traditional drug testing.
Bending light beams to your whim sounds like a job for a wizard or an a complex array of bulky mirrors, lenses and prisms, but a few tiny liquid bubbles may be all that is necessary to open the doors for next-generation, high-speed circuits and displays, according to Penn State researchers.
A U.K. team has developed a new type of high-performance, ultra-versatile Raman laser that harnesses diamonds to produce light beams with more power and a wider range of colors than current Raman lasers. Achievements by the team include the first “tunable” diamond Raman lasers, where the color of the light can be adjusted to meet specific needs, and the first continuously operating diamond Raman laser.
Random lasers are tiny structures emitting light irregularly into different directions, giving them a unique signature, like a fingerprint. Scientists in Austria have now shown that these exotic light sources, which differ greatly from conventional mirrored lasers, can be accurately controlled.
Built to handle oversized formats, the Trumpf TruLaser 8000 laser cuts sheet metal up to 52 feet in length. The machine is suitable for companies processing very large parts, or for job shops looking to expand their capacities and range of services.
A team in Germany has, for the first time, succeeded in functionally characterizing the active layer in organic thin-film solar cells using laser light for localized excitation of the material. This method, which relies on a highly modulated focused beam, enables them to directly map the spatial distribution of defects in organic thin films.
Most existing THz imaging devices employ prohibitively expensive technology or require several hours to generate a viable image. Researchers at Boston College recently reported a breakthrough in efforts to create accessible and effective THz imaging. Using both optical and electronic controls, the team developed a single-pixel imaging technique that uses a coded aperture to quickly and efficiently manipulate stubborn THz waves.
Researchers in Munich, Germany, have recently published work that describes experiments in which inexpensive semiconductor lasers have produced high-energy light pulses as short as 60 picoseconds without the drawbacks of previous approaches in terms of power consumption and device size. They say the new technique, based on the use of a new Fourier domain mode-locked laser, could open the door to subpicosecond pulses.
X-ray free-electron lasers (XFELs) produce higher-power laser pulses over a broader range of energies compared with most other x-ray sources. Although the pulse durations currently available are enormously useful for the study of materials, even shorter pulses are needed. Researchers at RIKEN have proposed a theoretical pulse-amplification scheme that allows for the production of ultrashort x-ray pulses at extremely high energies.
An international team of physicists working at King Abdullah University of Science and Technology in Saudi Arabia has demonstrated that chaos can beat order—at least as far as light storage is concerned. The researchers deformed mirrors in order to disrupt the regular light path in an optical cavity and, surprisingly, the resulting chaotic light paths allowed more light to be stored than with ordered paths.
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