Review Articles

Recent progress in terahertz scanning probe microscopy is reviewed with an emphasis on techniques that access length scales below 100 nm relevant to material science. An outlook on the future of nanoscale terahertz scanning probe microscopy is also provided.

Nearly 100 years after the prediction of Brillouin light-scattering spectroscopy, or Brillouin–Mandelstam light-scattering spectroscopy, the effect has proved itself a powerful tool for decades. Now its application to probing confined acoustic phonons, phononic metamaterials and magnons is reviewed.

A discussion of the evolution, present status and future outlook for tandem solar cells employing perovskite materials.

Recent effort in controlling the structure of light in all its degrees of freedom and dimensions has pushed the limits of structured light and broadened its potential beyond orbital angular momentum, two-dimensional fields, qubits and biphotons, and linear optical manipulation.

Photonics offers an attractive platform for implementing neuromorphic computing due to its low latency, multiplexing capabilities and integrated on-chip technology.

This Review covers the milestones for extreme-ultraviolet frequency combs and their applications. A future impact on the construction of nuclear-based optical clocks and multidimensional attosecond photoelectron spectroscopy of solids is remarked.

The potential of machine-learning application to the field of ultrafast photonics is reviewed, with key examples including pulsed lasers, and control and characterization of ultrafast propagation dynamics.

The application of deep learning to the design of photonic structures and devices is reviewed, including algorithm fundamentals.

Recent improvements of the operation speed of variable optical elements are reviewed with an emphasis on components with microsecond focus-varying response time.

The Review summarizes the progress of hybrid quantum photonics integration in terms of its important design considerations and fabrication approaches, and highlights some successful realizations of key physical resources for building integrated quantum devices, such as quantum teleporters, quantum repeaters and quantum simulators.

The prospects for improving photon upconversion systems by combining organic dyes and inorganic nanoparticles are reviewed.

This Review covers recent progress in integrated quantum photonics (IQP) technologies and their applications. The challenges and opportunities of realizing large-scale, monolithic IQP circuits for future quantum applications are discussed.

Front-induced transitions have been used in dispersion-engineered waveguides for frequency conversion, optical delays, and bandwidth and pulse duration manipulation. This Review provides a theoretical description of the subject and highlights the potential for light manipulation in guided optics.

Acousto-optical interactions within integrated optics platforms are reviewed with a discussion of the useful chip-based devices such as lasers, amplifiers, filters, isolators and more besides that can result.

This Review covers recent progress in AlGaN-based deep-ultraviolet light-emitting devices. The key technologies of how to improve their performance, carrier-injection efficiency, light extraction efficiency and heat dissipation are discussed.

Frequency comb spectroscopy is a recent field of research that has blossomed in the past five years. This Review discusses developments in the emerging and rapidly advancing field of atomic and molecular broadband spectroscopy with frequency combs.

This Review discusses the developments and applications of on-chip optical frequency comb generation based on two concepts—supercontinuum generation in photonic-chip waveguides and Kerr-comb generation in microresonators.

This Review describes quantum frequency combs that operate via photon entanglement, beginning with mode-locked quantum frequency combs followed by energy–time entanglement methods. The use of photonic integration and fibre-optic telecommunications components in enabling the quantum state control are also discussed.

This Review discusses recent advances of microwave photonic technologies and their applications in communications and information processing, as well as their potential implementations in quantum and neuromorphic photonics.

Rather than requiring millions of pixels, it is possible to make a camera that only needs one pixel. This Review details the working principle, advantages, technical considerations and future potential of single-pixel imaging.