Research articles

Researchers show that thin films containing HgTe quantum dots with diameters of around 10 nm exhibit a photoresponse in the mid-infrared that extends to wavelengths as long as 5 µm. Such films could become the basis of a new form of low-cost mid-infrared photodetector.

Researchers experimentally demonstrate that light propagating through a path-averaged zero-index dielectric medium can have zero phase delay, despite a non-zero physical path length. The medium is a superlattice consisting of layers of negative-refractive-index dielectric photonic crystals and positive-refractive-index homogeneous dielectric media.

Scientists demonstrate that strong single-cycle terahertz pulses can switch off interlayer superconductivity in a cuprate superconductor while leaving in-plane superconductivity unaltered. The effect may prove useful for studying and controlling the behaviour of future ultrafast nanoelectronics.

Researchers demonstrate a microwave generator based on a high-Q optical resonator and a frequency comb functioning as an optical-to-microwave divider. They generate 10 GHz electrical signals with a fractional frequency instability of ≤8 × 10⁻¹⁶ at 1 s.

Researchers report a colloidal quantum-dot solar cell that features two junctions, each designed to absorb and convert different spectral bands of light within the solar spectrum. The device offers a power conversion efficiency of 4.2% and an open circuit voltage of 1.06 V.

Poor coherence resulting from long exposure times is a problem for many coherent diffractive X-ray imaging schemes. Here, researchers show that coherent diffractive imaging using a broadband source can achieve a 60-fold reduction in exposure time.

Growing a group III–V quantum dot laser directly on a group IV substrate could provide silicon photonics with a convenient new form of laser source for use in optoelectronic circuitry.

Scientists demonstrate living biological lasers by pumping cells containing green fluorescent protein in a highly reflective microcavity. The researchers also investigate the thresholds and modes of their cellular lasers.

Scientists experimentally demonstrate an optical-fibre-based non-degenerate phase-sensitive amplifier link that offers broadband amplification, signal modulation-format independence and lower noise than links based on conventional erbium-doped fibre amplifiers.

Scientists study the coupling, guiding and polarizing of electromagnetic waves in graphene and demonstrate a graphene-based fibre polarizer that exhibits a transverse-electric-pass polarization at an extinction ratio of up to ∼27 dB in the telecommunications band.

Scientists show that spatiotemporal focusing and compression of non-Fourier-limited pulses through scattering media can be achieved by manipulating only the spatial degrees of freedom of the incident wavefront. This technique is potentially attractive for optical manipulation and nonlinear imaging in scattering media.

Researchers demonstrate active control over the spatial distributions of surface plasmon electromagnetic fields by using a digital spatial light modulator to manipulate the phase of the waves. Digital addressing of surface plasmons, which avoids the use of slow mechanical components, is hoped to enable new directions for imaging, sensing and data storage.

Researchers demonstrate the real-time generation and fast Fourier transformation of 10.8 Tbit s⁻¹ and 26 Tbit s⁻¹ line-rate optical frequency-division multiplexed signals, using an all-optical fast Fourier transform scheme based on cascaded delay interferometers and a time gate.

Using transformation optics, researchers predict that birefringent dielectrics can be engineered to control both polarizations of light independently. They also show that structures can be designed to allow light to pass through as if the birefringence did not exist at all.

By controlling the group velocity dispersion of a microresonator through proper shape design, scientists generate a comb whose central frequency can be tuned throughout the transparency window of the microresonator host material.

Scientists couple the zero-phonon line of individual nitrogen-vacancy centres to the modes of microring resonators fabricated in single-crystal diamond using standard semiconductor techniques, paving ways towards integrated diamond photonics.

Researchers demonstrate continuous-wave lasing from a quantum dot photonic crystal nanocavity at temperatures of up to 150 K. The achieved lasing thresholds of 181 nA (at 50 K) and 287 nA (at 150 K) are record-lows for any type of electrically pumped laser.

Researchers demonstrate a terahertz quantum cascade laser operating in a regime of active mode-locking by modulating its bias current with a radiofrequency synthesizer. This technique allows coherent sampling of the terahertz electric field as well as control over the laser's carrier–envelope phase shift.

Researchers cancel out the Dick effect through a synchronous frequency comparison between two optical lattice clocks based on ⁸⁷Sr and ⁸⁸Sr atoms. This scheme achieves an Allan standard deviation of around 10⁻¹⁷, which represents a significant advantage when using a large number (2,000) of atoms in an optical clock.

Using a tapered two-wire transmission line, researchers experimentally focus mid-infrared energy to a nanoscale confined spot with a diameter of 60 nm at the taper apex.