Volume 8 Issue 3, March 2014

Even for simple systems, the interpretations of new attosecond measurements are complicated and provide only a glimpse of their potential. Nonetheless, the lasting impact will be the revelation of how short-time dynamics can determine the electronic properties of more complex systems.

Researchers have demonstrated a compact, high-speed, surface-plasmon phase modulator that operates at telecommunication wavelengths over a wide range of operational conditions. It has the potential to boost the speed of future miniaturized integrated circuits.

A clever extension to a classic phase-contrast microscope allows speckle-free three-dimensional quantitative phase imaging of living cells in a tomographic imaging mode.

A source of entangled photons that emits one — and only one — pair of photons on demand has now been realized in a semiconductor chip. The solid-state source will be a useful resource for experiments in optical quantum information.

This review discusses significant recent advances in the generation, characterization and application of ultrabroadband isolated attosecond pulses with a spectral bandwidth comparable to the central frequency, which can in principle be compressed to a single optical cycle.

Attosecond light pulses are used for ultrahigh-resolution observations of ultrafast phenomena in atoms, molecules and condensed matter. Measuring the durations of such pulses is challenging because the spectrum lies in the vacuum ultraviolet or soft-X-ray range. This article reviews and compares two methods — photoionization and photorecombination — for measuring the duration of attosecond pulses.

Attosecond science allows the role of electronic coherence in the control of chemical reactions in molecular systems to be investigated. This article reviews recent activities in attosecond molecular science and identifies some promising directions for further development.

This article reviews the basic concepts underlying attosecond measurement and control techniques. Emphasis is given to exploring the fundamental speed limit of electronic signal processing that employs ultimate-speed electron metrology provided by attosecond technology.

A solid-state device is demonstrated that can detect the absolute offset between the carrier wave and envelope of an ultrashort pulse, the carrier–envelope phase. It holds promise for routine measurement and monitoring of the carrier–envelope phase in attosecond experimental set-ups.

An optical-frequency comb-based scheme is demonstrated that transfers a 4.5 × 10⁻¹⁶ fractional frequency stability from a 1,062-nm-wavelength laser to a 1,542-nm-wavelength laser. Transfer is also reported down to 4 × 10⁻¹⁸ at 1 s, which is one order of magnitude below that of previously reported work with comparable systems.

Polarization-entangled photon pairs are generated from an In(Ga)As quantum dot by setting the pump intensity such that the inversion of the quantum dot from the ground to the biexcitonic state is the most probable transition. On-demand generation is demonstrated with an ultrahigh purity, a high entanglement fidelity and high two-photon-interference non-post-selective visibilities.

A phase modulator that is only 29 µm long and operates at 65 GHz is demonstrated using plasmonics and the Pockels effect in a nonlinear polymer. The device operates across a 120-nm-wide wavelength range centred on 1,550 nm and at temperatures up to 85 °C.

A quantum memory for orbital angular momentum qubits is demonstrated in the single-photon regime. It is based on cold cesium atoms and the dynamic electromagnetically induced transparency protocol. Retrieved states were analysed by quantum tomography, and fidelities after readout of over 92% were obtained, confirming the quantum functionality of the storage process.

A photodiode-based logic device employing scalable heterojunctions of carbon nanotubes and silicon whose output currents can be manipulated by both optical and electrical inputs is developed. Bidirectional phototransistors and novel clock-triggerable logic elements, such as a mixed optoelectronic AND gate, a 2-Bit optoelectronic ADDER/OR gate and a 4-Bit optoelectronic D/A converter, are also demonstrated.

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.

Perovskite solar cells are currently generating great interest in the photovoltaics community, but a detailed understanding of why they are so efficient is lacking. Femtosecond laser spectroscopy and microwave photoconductivity measurements now reveal important insights into the photoinduced charge transfer processes and dynamics of such cells.

The three-dimensional structures of transparent objects, such as living cells, are captured by an imaging technique that uses white-light illumination and diffraction tomography to collect a stack of phase-based images.

Spectral purity can now be transferred from one laser to another with a very different wavelength at an order of magnitude better than previously achievable. Yann Le Coq spoke to Nature Photonics about the new development.

Attosecond photonics, currently one of the most promising branches of modern photonics, is progressing at an extremely rapid pace. Although still in its infancy, it has already captured the imagination of the scientific community with its promise of enhancing our understanding of ultrafast phenomena of direct relevance to life, technology and potentially medicine.