Nanowerk January 31, 2020 The bulk photovoltaic effect is a way to convert light into electrical current. An international team of researchers (USA – Boston College, UCLA, Germany, Switzerland) developed microscopic devices based on the Weyl semimetal tantalum arsenide. They had larger bulk photovoltaic effect than seen before. The devices they developed absorbed mid-infrared light, an important wavelength for devices that conduct chemical and thermal imaging as well as waste heat recovery. The observed magnitude and wavelength range of the shift current advances our fundamental understanding of the effects of topology in materials. It also demonstrates the utility of Weyl […]
Category Archives: Photonics
Converting absorbed photons into twice as many excitons
Science Daily September 24, 2019 An international team of researchers (Japan, Finland) found that when light was exposed to the surface of a tetracene alkanethiol-modified gold nanocluster, they were able to convert singlet oxygen at a highly efficient conversion rate of 160%, far exceeding 100% conversion, in comparison to the number of absorbed photons. An increase in lifetime of about 10,000 times was achieved by greatly suppressing the rapid loss of excitation energy on the metal surface. These findings are expected to contribute to areas such as solar energy conversion, electronics, life sciences, and medical care in the future…read more. […]
Engineers using soundwaves to search through big data with more stability and ease
Phys.org September 19, 2019 Using three aluminum rods, enough epoxy to connect them and some rubber bands for elasticity researchers at the University of Arizona have demonstrated the possibility for acoustic waves in a classical environment to do the work of quantum information processing without the time limitations and fragility. They sent a wave of sound vibrations down the rods, then monitored two degrees of freedom of the waves: what direction the waves moved down the rods and how the rods moved in relation to one another. To excite the system into a nonseparable state, they identified a frequency at […]
Light Seems to Pull Electrons Backward
American Physical Society Focus August 2, 2019 It is long assumed that light hitting a metal surface at an angle pushes on the free electrons, moving them forward. A team of researchers in the US (NIST, University of Maryland, Brown University) aimed an infrared laser toward the metal surface at a glancing angle and placed an electrode at the far end of the metal sample to detect any voltage created if the light drove the electrons along the metal, which would create an excess of negative charge at the far end. As they varied the angle, the team measured a […]
New property of light discovered
Phys.org June 28, 2019 An international team of researchers (Spain, USA – University of Colorado) has discovered a new property of light—self-torque. Their experiments involved firing two lasers at a cloud of argon gas—doing so forced the beams to overlap, and they joined and were emitted as a single beam from the other side of the argon cloud. The result was a type of vortex beam. Then they changed the the orbitatl momentum so that the lasers had different orbital angular momentum and they were slightly out of sync. This resulted in a beam that looked like a corkscrew with […]
Multicolored light twists in new knotted ways
Phys.org June 10, 2019 An international team of researchers (Spain, Austria, USA- University of Colorado) has designed a beam of light with a polarization state that forms three-lobed trefoils at each point by combining light of different frequencies (w and 2w), and making the trefoils connect to each other in a way such that the light beam, as a whole, has the shape of a knot. They found new conservation laws for non-linear optics which hold even in extreme situations where tens or hundreds of photons get combined to form single high-frequency photons and a new optical singularity, robust against […]
Recovering scattered data from twisted light via ‘scattering-matrix-assisted retrieval technique (SMART)’
Phys.org March 14, 2019 Multiplexing multiple orbital angular momentum (OAM) channels enables high-capacity optical communication but decreases the orthogonality between OAM channels for demultiplexing and eventually increases crosstalk in communication. To overcome this an international team of researchers (China, USA – Caltech, Howard Hughes Medical Institute, the Netherlands, France) developed scattering-matrix-assisted retrieval technique (SMART) to demultiplex OAM channels from highly scattered optical fields and achieve an experimental crosstalk of –13.8 dB in the parallel sorting of 24 OAM channels after passing through a scattering medium. They demonstrated high-fidelity transmission of images under scattering conditions at an error rate of <0.08%. using […]
Device that ‘shakes’ light a breakthrough In photonics
Nanowerk March 12, 2019 The nonlinear optical effects which used for manipulating photon frequency are weak and require a very strong laser, which creates “noise”. To better control light particles researchers at Yale University have created a device that consists of a series of waveguides. Light and microwave sent through the device wends its way through alternating suspended and clamped waveguides on a single chip. This creates a positive and negative effect, corresponding to the microwave. The light spirals in each of the waveguides to prolong the interaction and maximize efficiency. The deeper the modulation, the better you can control […]
Entangling photons of different colors
Science Daily February 25, 2019 A team of researchers in the US (NIST, University of Maryland) created quantum-correlated pairs made up of one visible and one near-infrared photon. The visible-light partners can interact with trapped atoms, ions, or other systems that serve as quantum versions of computer memory while the near-infrared members of each couple are free to propagate over long distances through the optical fiber. The design methods can be easily applied to create many other visible-light/near-infrared pairs tailored to match specific systems of interest. In the future, by combining two of the entangled pairs with two quantum memories, […]
New 3D printer shapes objects with rays of light
Science Daily January 31, 2019 A team of researchers in the US (UC Berkeley, Lawrence Livermore National Laboratory) has developed printer called “replicator” that relies on a resin composed of liquid polymers mixed with photosensitive molecules and dissolved oxygen. Light activates the photosensitive compound which depletes the oxygen. Only in those 3D regions where all the oxygen has been used up do the polymers form the “cross-links” that transform the resin from a liquid to a solid. Unused resin can be recycled by heating it in an oxygen atmosphere. A lot of the underlying theory behind the printer can be […]