Optical tweezers use the forces exerted by a strongly focused beam of light to trap and move objects ranging in size from tens of nanometres to tens of micrometres. Since their introduction in 1986, the optical tweezer has become an important tool for research in the fields of biology, physical chemistry and soft condensed matter physics. Recent advances promise to take optical tweezers out of the laboratory and into the mainstream of manufacturing and diagnostics; they may even become consumer products. The next generation of single-beam optical traps offers revolutionary new opportunities for fundamental and applied research.

http://physics.nyu.edu/grierlab/nreview2c/nreview2c.pdf

A revolution in optical manipulation

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10(-21). It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410(-180)(+160)  Mpc corresponding to a redshift z=0.09(-0.04)(+0.03). In the source frame, the initial black hole masses are 36(-4)(+5)M⊙ and 29(-4)(+4)M⊙, and the final black hole mass is 62(-4)(+4)M⊙, with 3.0(-0.5)(+0.5)M⊙c(2) radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.

/pdf/the-observation-of-gravitational-waves-from-a-binary-black-58srpupgg9.pdf

The Observation of Gravitational Waves from a Binary Black Hole Merger

With few exceptions biological tissues strongly scatter light, making high-resolution deep imaging impossible for traditional⎯including confocal⎯fluorescence microscopy. Nonlinear optical microscopy, in particular two photon–excited fluorescence microscopy, has overcome this limitation, providing large depth penetration mainly because even multiply scattered signal photons can be assigned to their origin as the result of localized nonlinear signal generation. Two-photon microscopy thus allows cellular imaging several hundred microns deep in various organs of living animals. Here we review fundamental concepts of nonlinear microscopy and discuss conditions relevant for achieving large imaging depths in intact tissue.

/pdf/deep-tissue-two-photon-microscopy-2aqu6d6n65.pdf

Deep tissue two-photon microscopy

Multiphoton microscopy (MPM) has found a niche in the world of biological imaging as the best noninvasive means of fluorescence microscopy in tissue explants and living animals. Coupled with transgenic mouse models of disease and 'smart' genetically encoded fluorescent indicators, its use is now increasing exponentially. Properly applied, it is capable of measuring calcium transients 500 microm deep in a mouse brain, or quantifying blood flow by imaging shadows of blood cells as they race through capillaries. With the multitude of possibilities afforded by variations of nonlinear optics and localized photochemistry, it is possible to image collagen fibrils directly within tissue through nonlinear scattering, or release caged compounds in sub-femtoliter volumes.

/pdf/nonlinear-magic-multiphoton-microscopy-in-the-biosciences-3fszv5aq8z.pdf

Nonlinear magic: multiphoton microscopy in the biosciences

Diarylethenes for Memories and Switches

In this paper, we experimentally demonstrate the sub-wavelength loss-less nano-imaging effect achieved by the surface-mode coupling in a negative refraction silicon photonic crystal at a wavelength of 1100 nm. The surface mode and nano-imaging effect of the photonic crystal are experimentally studied with a scanning near-field optical microscope. The thickness and the wavelength dependence of the full width at half maximum of the focal spot reveal a direct evidence of the surface-mode enhanced nano-imaging effect, which is consistent with the simulation. As a consequence, a focal spot with a lateral resolution of λ/3 at the predicted wavelength has been achieved.

https://researchbank.swinburne.edu.au/file/509a2148-dd75-4573-b301-a0c819d4c9dc/1/PDF (Published version).pdf

Surface-mode enhanced photonic-crystal nano-imaging observed by a scanning near-field optical microscope

Thermal stability of gold nanorod doped nanocomposites for optical patterning

Direct laser writing is a nanofabrication method used to develop three-dimensional nanostructures with almost arbitrary geometry. The fabrication of nanophotonic devices has been the major application of this technology to date. However, recent growth in the adoption of this technology and even commercialization of direct laser writing systems has extended the access of this nanofabrication method to a broader range of researchers including those in the fields of biology and biomimetics. In this review chapter the direct laser writing method and its recent application in developing biomimetic photonic materials are introduced.

Biomimetic photonic materials by direct laser writing

Quantum-dot (QD) surfaces were engineered for two-photon (2P) induced localized photorefractivity. The use of sulfur rich surfaced QDs not only optimized charge transfer and resultant refractive index change but expanded the optical recording thresholds.

https://researchbank.swinburne.edu.au/file/fb524e2b-a049-4994-ac8d-81a16b241966/1/PDF (Published version).pdf

Two-photon Induced Refractive Index Change In Quantum Dot Doped Photorefractive Polymer

The Single Gyroid, or srs, nanostructure has attracted interest as a circular-polarisation sensitive photonic material. We develop a group theoretical and scattering matrix method, applicable to any photonic crystal with symmetry I432, to demonstrate the remarkable chiral-optical properties of a generalised structure called 8-srs, obtained by intergrowth of eight equal-handed srs nets. Exploiting the presence of four-fold rotations, Bloch modes corresponding to the irreducible representations E- and E+ are identified as the sole and non-interacting transmission channels for right- and left-circularly polarised light, respectively. For plane waves incident on a finite slab of the 8-srs, the reflection rates for both circular polarisations are identical for all frequencies and transmission rates are identical up to a critical frequency below which scattering in the far field is restricted to zero grating order. Simulations show the optical activity of the lossless dielectric 8-srs to be large, comparable to metallic metamaterials, demonstrating its potential as a nanofabricated photonic material.

Min Gu

Papers

Surface-mode enhanced photonic-crystal nano-imaging observed by a scanning near-field optical microscope

Thermal stability of gold nanorod doped nanocomposites for optical patterning

Biomimetic photonic materials by direct laser writing

Two-photon Induced Refractive Index Change In Quantum Dot Doped Photorefractive Polymer

Group Theory of Chiral Photonic Crystals with 4-fold Symmetry: Band Structure and S-Parameters of Eight-Fold Intergrown Gyroid Nets