Volume 7 Issue 6, June 2013

Organic photovoltaics offer the tantalizing promise of low-cost plastic coatings that can be applied to building surfaces and roofing to generate electricity sustainably. Now, the demonstration that the addition of organic dyes can improve device performance by energy-transfer processes offers an exciting new opportunity.

Using a pump–probe technique, scientists have experimentally demonstrated a nonlinear imaging scheme that permits the super-resolution imaging of nonfluorescent samples, making it promising for use with unstained specimens.

Enhancing magneto-optic effects may help to reduce the size of photonic devices. Recent research by several groups shows that the features of metal optical components can be exploited to enhance typically weak magneto-optic effects.

Deformed optical resonators that support chaotically propagating modes have been shown to store more light energy than conventional cavities.

Nanophotonics is of both fundamental and applied importance. This field has a wide range of applications, including light-emitting devices and optical integrated circuits.

Using two-way exchange between coherent frequency combs, each phase-locked to the local optical oscillator, optical time–frequency transfer is demonstrated in free space across a 2-km-long link, with a timing deviation of 1 fs, a residual instability below 10⁻¹⁸ at 1,000 s and systematic offsets below 4 × 10⁻¹⁹.

A quantum ‘tele-amplification’ scheme that combines teleportation and the noiseless amplification of a coherent state is demonstrated by using Schrödinger-cat states prepared by photon subtraction from squeezed vacuum as an entanglement resource. This scheme can realize high-capacity communication, thus beating the homodyne limit of optical communications.

In vivo, high-resolution, deep-tissue imaging of biological tissue is made possible by three-dimensional interferometric synthetic aperture microscopy. The method operates in real time and provides improved depth of field and resolution compared with conventional forms of optical coherence tomography.

A scheme for overcoming the diffraction limit in the far-field imaging of non-fluorescent species is demonstrated. This technique, which is based on the spatially controlled saturation of electronic absorption, may enable the super-resolution imaging of nanomaterials and non-fluorescent chromophores.

Focusing beyond the diffraction limit is achieved by using elastic light scattering from a highly turbid medium to convert propagating far-field components into near-field wave vectors. This finding may open new avenues for the subwavelength control of light, with applications in nanolithography and the interconnection between nanoelectronics and nanophotonics.

A simple two-terminal device containing a semiconducting single-walled-nanotube thin-film is reported that generates an extremely high density of holes when it comes in contact with an ionic liquid, inducing strong electromodulation of the interband and excitonic transitions as a result of the position-dependent shift of the single-walled-nanotube Fermi level.

Highly strained germanium on silicon samples with up to 3.1% uniaxial strain are fabricated and then investigated by Raman spectroscopy. During optical pumping, changes in both the emission wavelength and output power are observed, indicating that bandgap modification and optical gain are occurring.

Chaotic resonators constructed from planar silicon-on-insulator photonic crystals and deformed polystyrene microspheres are demonstrated to store up to six times more light energy than their classical, non-chaotic counterparts. This effect is attributed to the modification of the trajectories and lifetimes of photons in the cavity.

The addition of squaraine dye to a polymer bulk heterojunction solar cell is shown to enhance light harvesting and cell efficiency through Förster resonance energy transfer.

Inorganic–organic hybrid dye-sensitized solar cells featuring a perovskite compound as a light harvester and a polymer as a hole transporter provide an open-circuit voltage of almost 1 V and a power conversion efficiency of 12% under standard illumination conditions.

A novel non-thermal photomagnetic torque originating from spin–orbit coupling of non-equilibrium photocarriers excited by helicity-independent laser pulses is found in (Ga,Mn)As thin films. It differs fundamentally from optical spin–transfer torque. The possibility of studying spin–orbit torques on short timescales achievable by pump–probe magneto-optical measurements is demonstrated.

Magnets are often electrically activated, but recent research has demonstrated various schemes that can control magnetization using light and photocarriers. Nature Photonics spoke to Petr Němec and Tomas Jungwirth about their recent work on a polarization-independent optical-torque approach.