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

We report on the study of the emission property of PbSe QDs embedded in 3D woodpile polymer PCs fabricated by the two-photon polymerization (2PP) method. Photonic band gaps (PBGs) of PCs were tuned towards longer wavelengths by infiltrating the QDs. A spectral redistribution in spontaneous emission from QDs inside a 3D PC has been measured for both low and high concentrations of infiltration.

https://researchbank.swinburne.edu.au/file/48d1169c-8e00-4ec7-874c-d18e93bb91d8/1/PDF (Published version).pdf

Spectral redistribution in spontaneous emission from quantum dot infiltrated three-dimensional photonic crystals

Confocal reflection readout thresholds in two-photon-induced optical recording in photoisomerization polymer are studied both theoretically and experimentally. A threshold of the axial response from a planar reflector with a refractive-index change of the order of 10−2 is revealed. However, the threshold is reduced to 0.006 when strong forward scattering caused by the recorded bits leads to multiple reflection between the bit and the rare surface, which enhances the image contrast and reduces the readout threshold. The quality of the reconstructed bit image is strongly dependent on the refractive-index mismatch at the sample rare interface as well as the distance between the recorded position and the rare surface.

https://researchbank.swinburne.edu.au/file/1f75834d-354d-4f8a-af59-bf6d40fe015d/1/PDF (Published version).pdf

Confocal reflection readout thresholds in two-photon-induced optical recording.

The coupling between solid-state quantum emitters and nanoplasmonic waveguides is essential for the realization of integrated circuits for various quantum information processing protocols, communication, and sensing. Such applications benefit from a feasible, scalable and low loss fabrication method as well as efficient coupling to nanoscale waveguides. Here, we demonstrate optomagnetic plasmonic nanocircuitry for guiding, routing and processing the readout of electron spins of nitrogen vacancy centres. This optimized method for the realization of highly efficient and ultracompact plasmonic circuitry is based on enhancing the plasmon propagation length and improving the coupling efficiency. Our results show 5 times enhancement in the plasmon propagation length using (3-mercaptopropyl)trimethoxysilane (MPTMS) and 5.2 times improvement in the coupling efficiency by introducing a grating coupler, and these enable the design of more complicated nanoplasmonic circuitries for quantum information processing. The integration of efficient plasmonic circuitry with the excellent spin properties of nitrogen vacancy centres can potentially be utilized to extend the applications of nanodiamonds and yield a great platform for the realization of on-chip quantum information networks.

/pdf/optomagnetic-plasmonic-nanocircuits-4h3ovcgxv0.pdf

Optomagnetic plasmonic nanocircuits

In this report we show the application of silica coated gold nanorods to optical data storage. We show controlled growth of a thick silica shell onto gold nanorods. The coated nanorods are transferred into a PVA matrix and data patterns are recorded. A silica layer on the nanorods dissipates the heat and the matrix does not melt, allowing reliable data storage.

https://researchbank.swinburne.edu.au/file/8f17e233-2631-47e1-8b9d-6bfbf2e3b534/1/PDF (Published version).pdf

Functionalisation of gold nanorods and its application to optical data storage

The symmetry of a Fabry-Perot-like planar cavity embedded within a three-dimensional (3D) woodpile photonic crystal prevents the observation of polarization effects. In this letter we propose a geometry to break the degeneracy of the Fabry-Perot-like cavity modes by introducing asymmetry. The introduction of a one-dimensional (1D) lattice to the centre of a planar cavity allows for distinct modes parallel (TE) and perpendicular (TM) to the layer. This hybrid 3D-1D-3D lattice structure exhibits a pronounced increase in the quality-factor, and in particular shows an increase of up to 50% more than that of a planar cavity for TM modes.

https://researchbank.swinburne.edu.au/file/b0a190e4-8347-450e-915d-2800635969d6/1/PDF (Published version).pdf

Min Gu

Papers

Spectral redistribution in spontaneous emission from quantum dot infiltrated three-dimensional photonic crystals

Confocal reflection readout thresholds in two-photon-induced optical recording.

Optomagnetic plasmonic nanocircuits

Functionalisation of gold nanorods and its application to optical data storage

Polarization control of defect modes in three-dimensional woodpile photonic crystals