Science Daily August 12, 2019 A team of researchers in the US (UC San Diego, City University of New York, Johns Hopkins University) present an experimental demonstration of light guiding in an atomically thick tungsten disulfide membrane patterned as a photonic crystal structure. In this scheme, two-dimensional tungsten disulfide excitonic photoluminescence couples into quasi-guided photonic crystal modes known as resonant-type Wood’s anomalies. These modes propagate via total internal reflection with only a small portion of the light diffracted to the far field. Such light guiding at the ultimate limit provides more possibilities to miniaturize optoelectronic devices and to test fundamental […]
Tag Archives: Photonics
‘Tsunami’ on a silicon chip: A world first for light waves
Science Daily July 3, 2019 An international team of researchers (Singapore, Australia) has shown CMOS‐compatible, on‐chip Bragg solitons, with a soliton‐effect pulse compression with a factor of × 5.7, along with time‐resolved measurements of soliton fission on a CMOS‐compatible photonic circuit platform. These observations are enabled by the combination of a unique cladding‐modulated Bragg grating design and the high nonlinearity and negligible nonlinear loss of compositionally engineered ultra‐silicon‐rich nitride (USRN: Si7N3). Manipulating solitons on-chip could potentially allow for the speed up of photonic communications devices and infrastructure…read more. TECHNICAL ARTICLE
How to bend waves to arrive at the right place
Science Daily June 24, 2019 Electronic matter waves traveling through the weak and smoothly varying disorder potential of a semiconductor show a characteristic branching behavior instead of a smooth spreading of flow. By transferring this phenomenon to optics, researchers at Harvard University demonstrated numerically, how the branched flow of light can be controlled to propagate along a single branch rather than along many of them at the same time. The method is based on shaping the incoming wavefront and only requires partial knowledge of the system’s transmission matrix. They show that the light flowing along a single branch has a […]
Sculpting super-fast light pulses
Science Daily May 2, 2019 A team of researchers (NIST, University of Maryland) has demonstrated how dielectric metasurfaces can be leveraged to shape the temporal profile of a near-infrared femtosecond pulse. Finely tailored pulse shaping operations, including splitting, compression, chirping and higher-order distortion are achieved using a Fourier-transform setup embedding metasurfaces able to manipulate, simultaneously and independently, the amplitude and phase of the constituent frequency components of the pulse. Exploiting metasurfaces to manipulate the temporal characteristics of light expands their impact and opens new vistas in the field of ultrafast science and technology…read more. TECHNICAL ARTICLE
A polariton filter turns ordinary laser light into quantum light
Phys.org February 19, 2016 An international team of researchers (Australia, France) used nanometre-thick films made of gallium arsenide and sandwiched them between two mirrors to manipulate the incoming photons. The photons interact with electron-hole pairs in the semiconductor, forming polaritons that carry properties from both the photons and the electron-hole pairs. The polaritons decay after a few picoseconds, and the photons they release exhibit distinct quantum signatures. While these quantum signatures are weak at the moment, the work opens a new avenue for producing single photons on demand. Once they are able to increase the strength of the quantum signatures, […]
Invisible tags: Physicists write, read and erase using light
Nanowerk February 1, 2019 Researchers in Germany introduced organic luminescent molecules plastic foils. In the beginning, these molecules are in an inactive, dark state. By locally using ultraviolet irradiation, it is possible to turn the dark state into an active, luminescent one. By mask illumination or laser writing, activated patterns can be printed and the imprinted information can be read. Ultraviolet radiation induces a chemical reaction which efficiently removes the oxygen from the layer activating the luminescent molecules. By illuminating with infrared light, the tag is erased completely, and new data can be written into it. The deactivation process is […]
Scientists design new material to harness power of light
Phys.org December 17, 2018 An international team of researchers (USA – MIT, University of Hartford, UK. France) found that several materials with poor nonlinear characteristics can be combined, resulting in a new metamaterial that can be “tuned” to change the color of light. The enhancement comes from the way the metamaterial reshapes the flow of photons. They describe the underlying physics, compare its predictions to the experimental results, and analyze the limits of its applicability. The work opens a new direction in controlling the nonlinear response of materials and may find applications in on-chip optical circuits, drastically improving on-chip communications…read […]
Shedding a new light on optical trapping and tweezing
Eurekalert November 27, 2018 While holographic optical trapping and tweezing is not new, an international team of researchers (South Africa, USA – MIT) found a way to optimally use the full force of light – including vector light to control and manipulate minute objects such as single cells in a human body, tiny particles in small volume chemistry, or working on future on-chip devices. They showed how to create and control any pattern of light holographically, and then used this to form a new optical trapping and tweezing device…read more. Open Access TECHNICAL ARTICLE
Light-bending tech shrinks kilometers-long radiation system to millimeter scale
Phys.org October 26, 2018 A team of researchers in the US (University of Michigan, Purdue University) used a laser to produce a pulse of visible light that lasts for one trillionth of a second. The array of antennae causes the light pulse to accelerate along a curved trajectory inside the crystal. The light pulse displaced electrons from their equilibrium positions to create dipole moments which accelerated along the curved trajectory of the light pulse resulting in the emission of synchrotron radiation much more efficiently at the terahertz range. The work demonstrates that synchrotron radiation could eventually help develop on-chip terahertz […]
U-M researchers develop small device that bends light to generate new radiation
University of Michigan October 25, 2018 Synchrotron radiation is usually generated at large-scale facilities. A team of researchers in the US (University of Michigan, Purdue University) developed a way to produce synchrotron radiation by printing a pattern of microscopic gold antennae on lithium tantalate metasurface. They use a laser that produces ultrashort pulses of light which last for one trillionth of a second. The array of antennae causes the light pulse to accelerate along a curved trajectory inside the crystal producing synchrotron radiation that contains many terahertz frequencies. They hope to refine their device so that the light pulse revolves […]