Volume 6 Issue 7, July 2012

Plasmonics can be used to enhance mid-infrared sources, sensors and detectors for applications such as chemical sensing, thermal imaging and heat scavenging. The challenge now is to integrate these technologies in cost-effective, compact and reliable platforms.

Using a real-time measurement technique to study the single-shot properties of modulation instability, scientists have shown that its initial stochastic nature in an optical system can lead to specific correlation properties in both the spectral and temporal domains.

Phase-space optics is an indispensable tool for optical imaging and sensing. New optical hardware for light-field photography and pupil engineering for imaging with extended depth of field promote the use of phase-space representations as the primary object of optical signal processing.

Researchers in the field of metamaterials are not only making advances in existing areas of plasmon dispersion control and slow-light propagation in photonic crystals, but also tackling new topics such as quantum metamaterials.

Exploiting the spatial shapes of 'twisted' photons makes it possible to enhance the bit rate of free-space optical communications without requiring more bandwidth.

Fibre lasers in the mid-infrared regime are useful for a diverse range of fields, including chemical and biomedical sensing, military applications and materials processing. This Review summarizes the different rare-earth cations and host materials used in mid-infrared fibre laser technology, and discusses the future applications and challenges for the field.

The design flexibility of quantum cascade lasers has enabled their expansion into mid-infrared wavelengths of 3–25 μm. This Review focuses on the two major areas of recent improvement: power and power efficiency, and spectral performance.

This Review discusses the emerging field of mid-infrared frequency comb generation, including technologies based on novel laser gain media, nonlinear frequency conversion and microresonators, as well as the applications of these combs in precision spectroscopy and direct frequency comb spectroscopy.

Researchers report a three-dimensional metal–dielectric optical cavity with an ultrahigh optical index of 17.4. The resonant frequency of the cavity is constant and independent of its size. This unique property could be used to provide significant enhancements to a broad range of light–matter interactions.

Researchers investigate the internal gain of InAsP quantum dots embedded in an InP nanowire by performing photocurrent measurements down to the single-photon regime. The resulting gain ( > 10⁴) is a significant step towards single-shot electrical read-out of an exciton qubit state for the transfer of quantum information between flying and stationary qubits.

Researchers demonstrate spontaneous emission enhancements approaching 1,000 for emitters coupled to the gap between a metal wire and a metal substrate. The enhanced emission rate of plasmons in the structures is shown to yield a high internal quantum efficiency, despite the close proximity of lossy metal surfaces.

Researchers report the spontaneous appearance of discrete frequency modes in a real-time experimental investigation of pulsed modulation instability in an optical system. These findings are expected to impact modulation instability-induced characteristics across a broad range of physical situations and technological systems, including free-electron lasers.

Researchers demonstrate an ultrastrong optical trap capable of operating with nanonewton optical forces by employing tailor-made high-refractive-index particles. This work could could lead to the development of highly efficient light-driven machines.

Researchers use spatial light modulators to create beams with locally varying spatial coherence, and show that the space and spatial frequency information of the beams can be measured simultaneously.

Based on observations in crystalline MgF₂ and planar Si₃N₄ microresonators, scientists reveal that the existence of multiple and broad-beat notes in a Kerr-frequency comb is due to the formation dynamics of the comb itself. This work identifies the conditions requires for low-phase-noise performance and also helps to elucidate a number of yet-unexplained phenomena.

Researchers demonstrate the ability to multiplex and transfer data between twisted beams of light with different amounts of orbital angular momentum — a development that provides new opportunities for increasing the data capacity of free-space optical communications links.

Twisted light beams with different values of orbital angular momentum can be used to provide dramatic increases in the capacity of free-space optical communications. Nature Photonics spoke to Alan Willner at the University of Southern California to find out more.

The mid-infrared spectral region of 2-20 μm contains strong characteristic vibrational transitions of many important molecules as well as two atmospheric transmission windows of 3-5 μm and 8-13 μm, which makes it crucial for applications in spectroscopy, materials processing, chemical and biomolecular sensing, security and industry. This Focus Issue covers recent developments in sophisticated laser technologies such as quantum cascade lasers, fibre lasers and frequency combs, and discusses how plasmonics can be exploited in the mid-infrared regime.