Articles

A cavity quantum electrodynamics system comprising a quantum emitter and an optical cavity is theoretically investigated. The outcoupling process for the N-photon state of the cavity is simulated. The numerical calculations predict the possibility of operating this system as a source of N-photon bundles with a tunable integer N.

Large-scale densely integrated optical memory on a single photonic crystal chip is demonstrated. The wavelength-division-multiplexing (WDM) capabilities of nanophotonic memories are exploited for optical addressing. This work may enable optical random-access memories and a large-scale WDM photonic network-on-chip.

Recent demonstrations of modulators, polarization rotators and isolators have indicated the potential of graphene for photonic applications. The present study investigates the fundamental limits and near-optimal design of graphene modulators and non-reciprocal devices.

Theoretical analysis reveals that spasers do not differ fundamentally from conventional semiconductor lasers; differences are mainly technical and result from loss in the metal. Spasers are shown to have significantly inferior threshold currents and linewidths to those of vertical-cavity surface-emitting lasers, but their speed can be slightly greater.

High-resolution diffuse optical tomography employing a large array of light sources and detectors arranged around the head can perform functional brain imaging. It provides an alternative to magnetic resonance imaging for monitoring activity in different areas of the brain.

By integrating a photoacoustic transmitter based on a carbon nanotube nanocomposite and an optical microring resonator as an ultrasonic sensor, a low-noise terahertz pulse detection system is demonstrated at room temperature. The response time and the noise-equivalent detectability energy are on the order of 0.1 µs and 220 pJ, respectively.

Frequency combs based on terahertz quantum cascade lasers, which combine the high power of lasers with the broadband capabilities of pulsed sources, are demonstrated. The frequency combs generate 5 mW of terahertz power covering a frequency range of almost 500 GHz and produce more than 70 lines at 3.5 THz.

An investigation of the use of nonlinear upconversion effects like second-harmonic generation and four-wave mixing within biological tissue indicates that it should be possible to perform photodynamic therapy with near-infrared laser light at greater depths than previously.

The integration of germanium quantum-well devices and low-loss waveguides with silicon substrates shows promise for realizing low-loss, on-chip photonic interconnects.

Perovskite solar cells containing tin rather than lead, which is usually employed, are reported. These cells have a power conversion efficiency of 5.7% and retain 80% of their performance over a period of 12 hours.

Cavity-stimulated Raman spin-flip emission is demonstrated by coupling a negatively charged InAs/GaAs quantum dot to a photonic crystal defect cavity. The emission is spectrally narrow and tunable over a range of about 125 GHz. The process can be made spin selective by tuning the scattered photons to be in resonance with the cavity.

Through shaping of colloidal particles, optical traps with prescribed force–displacement profiles are generated and are used to design a microscopic constant-force spring capable of delivering a constant piconewton-scale restoring force for displacements of several micrometres. Potential future applications include the imaging of sensitive biological membranes.

By exploiting hot-carrier injection, the photodetection capabilities of a semiconductor structure have been extended to wavelengths as long as 55 µm, which is well beyond the usual spectral limits determined by energy levels.

Researchers demonstrate a watt-class high-power, single-mode photonic-crystal laser operating continuously at room temperature. A beam quality of M² ≤ 1.1 is achieved.

Stokes-shift-engineered CdSe/CdS quantum dots are used to fabricate luminescent solar concentrators that are tens of centimetres long and do not exhibit reabsorption losses. With efficiencies of over 10% and an effective concentration factor of 4.4, they demonstrate the potential of using Stokes-shift-engineered quantum dots in large-area luminescent solar concentrators.

X-ray scattering experiments indicate that the molecular orientation at the interfaces of bulk heterojunction organic solar cells influences the cells’ fill factor and short-circuit current.

Emulation of noiseless linear amplification of quantum states of light is demonstrated by post-selection of measurement data obtained by heterodyne detection. Using this protocol, Einstein–Podolsky–Rosen entanglement is recovered after its degradation by transmission loss. This protocol is applicable to other quantum communication protocols, including teleportation and remote state preparation.

Blue organic light-emitting diodes that harness thermally activated delayed fluorescence are realized with an external quantum efficiency of 19.5% and reduced roll-off at high luminance.

An integrated nanoscale light-emitting diode is used as an electrically driven optical source for exciting two-dimensionally localized gap plasmon waveguides with a 0.016λ² cross-sectional area. Electrically driven subwavelength optical nanocircuits for routing, splitting and directional coupling are demonstrated in compact and relatively low-loss gap plasmon waveguide structures.

A dual-wavelength fibre laser source has been developed for stimulated Raman scattering microscopy. It is precisely tunable over the entire high-wavenumber region of Raman spectra, where most stimulated Raman scattering imaging is performed. Imaging speeds of up to 1 frame s⁻¹ with shot-noise-limited sensitivity were achieved.