With the cavity of the laser the beam of light is reflected back and forth along the central tube, until the waves of light become coherent. Movement of light in a laser. Coherent light wave pattern Incoherent light wave pattern Searching the web for information on Lasers can be exhausting if you use the "adult" search engines.
The subject matter in the adult search engines will give you career and industry information, which is too difficult for young students. These type of search engines give students sites that may help them understand what lasers are all about. As the students are filling in the worksheet, have them search the web if they wanted to learn more about lasers.
Possible applications of metamaterials include ultrahigh-resoln. This Review describes recent progress in the fabrication of three-dimensional metamaterial structures and discusses some of the remaining challenges. Flat optics with designer metasurfaces. Conventional optical components such as lenses, waveplates and holograms rely on light propagation over distances much larger than the wavelength to shape wavefronts.
In this way, substantial changes of the amplitude, phase or polarization of light waves are gradually accumulated along the optical path. Metasurfaces are generally created by assembling arrays of miniature, anisotropic light scatterers i.
The spacing between antennas and their dimensions are much smaller than the wavelength. As a result the metasurfaces, on account of Huygens principle, are able to mold optical wavefronts into arbitrary shapes with subwavelength resoln. Such gradient metasurfaces go beyond the well-established technol. Metasurfaces can also be created by using ultrathin films of materials with large optical losses. By using the controllable abrupt phase shifts assocd.
Theory and applications of guided-mode resonance filters. The guided-mode resonance properties of planar dielectric waveguide gratings are presented and explained. It is shown that these structures function as filters that produce complete exchange of energy between forward- and backward-propagating diffracted waves with smooth line shapes and arbitrarily narrow filter linewidths.
Furthermore, the resonance regimes, defining the parametric regions of the guided-mode resonances, can be directly visualized. It is shown that the linewidths of the resonances can be controlled by the grating modulation amplitude and by the degree of mode confinement refractive-index difference at the boundaries.
Examples presented of potential uses for these elements include a narrow-line polarized laser, a tunable polarized laser, a photorefractive tunable filter, and an electro-optic switch.
The guided-mode resonance filter represents a basic new optical element with significant potential for practical applications.
Progress in 2D photonic crystal Fano resonance photonics. Quantum Electron. Light in tiny holes. Nature , , 39 — 46 , DOI: The presence of tiny holes in an opaque metal film, with sizes smaller than the wavelength of incident light, leads to a wide variety of unexpected optical properties such as strongly enhanced transmission of light through the holes and wavelength filtering.
These intriguing effects are now known to be due to the interaction of the light with electronic resonances in the surface of the metal film, and they can be controlled by adjusting the size and geometry of the holes. This knowledge is opening up exciting new opportunities in applications ranging from subwavelength optics and optoelectronics to chem. Nanohole array as a lens.
Nano Lett. American Chemical Society. A quasi-crystal array of nanoholes in a metal screen can mimic a function of the lens: 1-to-one imaging of a point source located a few tens of wavelengths away from the array to a point on the other side of the array. A displacement of the point source leads to a linear displacement of the image point. Complex structures composed of multiple point sources can be faithfully imaged with resolns. The concept of optical phase discontinuities is applied to the design and demonstration of aberration-free planar lenses and axicons, comprising a phased array of ultrathin subwavelength-spaced optical antennas.
The lenses and axicons consist of V-shaped nanoantennas that introduce a radial distribution of phase discontinuities, thereby generating resp.
Simulations are also presented to show that aberration-free designs are applicable to high-numerical aperture lenses such as flat microscope objectives. The authors study a planar, holey-metal lens made as a set of concentric circular arrays rings of nanoscale holes milled in a subwavelength-thick metal film.
Each nanohole-a finite-length, circular, single-mode waveguide with a radius-dependent mode index-is used as a phase-shifting element. The proposed concept could offer an alternative to conventional refraction microlenses and open up a vital path toward on-chip or fiber-end planar photonic devices for biosensing and imaging.
Metasurface for characterization of the polarization state of light. Express , 23 , — , DOI: Optical Society of America. The miniaturization of measurement systems currently used to characterize the polarization state of light is limited by the bulky optical components used such as polarizers and waveplates. We propose and exptl.
A completely polarized light beam is decompd. By measuring the intensities of the refracted light spots, the ellipticity and handedness of various incident polarization states are characterized at a range of wavelengths and used to det. To fully characterize the polarization state of light, an extra polarizer can be used to measure the polarization azimuth angle of the incident light.
Plasmonic metagratings for simultaneous determination of Stokes parameters. Optica , 2 , — , DOI: Measuring light's state of polarization is an inherently difficult problem since the phase information between orthogonal polarization states is typically lost in the detection process.
In this work, we bring to the fore the equivalence between normalized Stokes parameters and diffraction contrasts in appropriately designed phase-gradient birefringent metasurfaces and introduce a concept of all-polarization birefringent metagratings.
The metagrating, which consists of three interweaved metasurfaces, allows one to easily analyze an arbitrary state of light polarization by conducting simultaneous i. Based on plasmonic metasurfaces operating in reflection at a wavelength of nm, we design and realize phase-gradient birefringent metasurfaces and the correspondent metagrating, while exptl.
We foresee the use of the metagrating in compact polarimetric setups at any frequency regime of interest. Omnidirectional and broadband absorption enhancement from trapezoidal Mie resonators in semiconductor metasurfaces.
Light trapping in planar ultrathin-film solar cells is limited due to a small no. A nanostructured thin-film design could surpass this limit by providing broadband increase in the local d. Here we report a broadband metasurface design, enabling efficient and broadband absorption enhancement by direct coupling of incoming light to resonant modes of subwavelengthscale Mie nanoresonators defined in the thin-film active layer. Absorption was investigated both theor. A crossed trapezoid resonator shape of rectangular cross section is used to excite broadband Mie resonances across visible and near-IR spectra.
Our numerical simulations, optical absorption measurements and photocurrent spectral response measurements demonstrate that crossed trapezoidal Mie resonant structures enable angle-insensitive, broadband absorption. A short circuit c. It is suggested that silicon metasurfaces with Mie resonator arrays can provide useful insights to guide future ultrathin-film solar cell designs incorporating nanostructured thin active layers. Nanostructured metal film with asymmetric optical transmission.
Schwanecke, A. A nanostructured planar photonic metamaterial transmitting light differently in forward and backward directions is demonstrated.
Menzel, C. American Physical Society. We exptl. The observation of this novel effect requires a metamaterial composed of three-dimensional chiral meta-atoms without any rotational symmetry. Our anal. Contrary to phys. Specular optical activity of achiral metasurfaces. American Institute of Physics. Optical activity in 3D-chiral media in the form of CD and birefringence is a fundamental phenomenon that serves as evidence of life forms and is widely used in spectroscopy.
Even in 3D-chiral media exhibiting strong transmission optical activity, the reflective effect is weak and sometimes undetectable. Here, we report that specular optical activity at structured interfaces can be very strong. The effect arises at oblique incidence from a 3D-chiral arrangement of the wave's direction and the metasurface's structure that itself does not possess chiral elements. Specular optical activity of such magnitude is unprecedented.
It is fundamentally different from the polarization effects occurring upon scattering, reflection, and transmission from surfaces with 2D-chiral patterns. The scale of the effect allows applications in polarization sensitive devices and surface spectroscopies. There is no corresponding record for this reference. Google Scholar There is no corresponding record for this reference. Interspecimen comparison of the refractive index of fused silica.
The n of optical-quality fused silica SiO2 was detd. The variation in n between 12 specimens was detd. Dispersive properties of the material and thermal coeff. A comparison with previous Natl. Bureau of Standards index data is discussed. Magnetic Response of Metamaterials at Terahertz. Science , , — , DOI: American Association for the Advancement of Science. An array of single nonmagnetic metallic split rings can be used to implement a magnetic resonance, which arises from an inductor-capacitor circuit LC resonance, at THz frequency.
The excitation of the LC resonance in the normal-incidence geometry used in our expts. The measured optical spectra of the nanofabricated gold structures come very close to the theor. Together with an elec. Magnetic Metamaterials at Telecommunication and Visible Frequencies. Researchers then had the idea of using atoms and molecules as the resonant structures, but unfortunately the power available from just one electron transition is very small and it only occurs intermittently.
Scientists therefore had to try and persuade all the atoms in a specimen to react simultaneously since this would produce a powerful coherent wave. It can be caused, for example, by chemical reactions, electrical energy, subatomic motion or stress on a crystal.
There are different types of luminescence:. Why is CL so interesting and why would we want to look at it? Cathodoluminescence is a visible measure of what is taking place inside a material or an organism. When looking at materials with conventional methods, such as optical microscopy, it is impossible to achieve the same spatial resolution as with electron microscopy. Cathodoluminescence is a great tool for looking at light with very high spatial resolution. Incoherent cathodoluminescence emission occurs when the material is excited with an electron beam, where the primary electrons decelerate and deposit energy into the material.
An important property of incoherent CL is that there is no fixed phase relation between a photon that is emitted and incoming excitation electron. In geological materials, for instance, several defects may be present, some of which have a distinct CL signature. CL emission from these materials can be divided into extrinsic and intrinsic CL read more in our recent blog post.
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