July 2012 Volume 6, Issue 7

Editorial

Extending opportunities   p407
doi:10.1038/nphoton.2012.164
Innovative mid-infrared laser technologies are anticipated to broaden the applications of existing mid-infrared laser sources and bring unexpected scientific discoveries.

Commentary

Plasmonics in the mid-infrared   pp409 - 411
Ross Stanley
doi:10.1038/nphoton.2012.161
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.

Research Highlights

Organic photonics: High-voltage surprise | Spectroscopy: Probing the mid-infrared | Coupled-mode theory: Time-dependence | Lasers: Nanowire behaviour | Nonlinear optics: Silicon nitride success | Graphene: Plasmons and magnetism | Optofluidics: Reconfigurable hybrid | Slow light: Enhancement revisited | Supercontinua: Broader than ever | Colloidal nanocrystals: Single-exciton lasing

News and Views

Correction

The behaviour of exciton–polaritons   p422
doi:10.1038/nphoton.2012.163

Reviews

Towards high-power mid-infrared emission from a fibre laser   pp423 - 431
Stuart D. Jackson
doi:10.1038/nphoton.2012.149
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.

Mid-infrared quantum cascade lasers   pp432 - 439
Yu Yao, Anthony J. Hoffman and Claire F. Gmachl
doi:10.1038/nphoton.2012.143
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.

Mid-infrared frequency combs   pp440 - 449
Albert Schliesser, Nathalie Picqué and Theodor W. Hänsch
doi:10.1038/nphoton.2012.142
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.

Letters

Experimental realization of three-dimensional indefinite cavities at the nanoscale with anomalous scaling laws   pp450 - 454
Xiaodong Yang, Jie Yao, Junsuk Rho, Xiaobo Yin and Xiang Zhang
doi:10.1038/nphoton.2012.124
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.

Avalanche amplification of a single exciton in a semiconductor nanowire   pp455 - 458
Gabriele Bulgarini, Michael E. Reimer, Mo&iouml;ra Hocevar, Erik P. A. M. Bakkers, Leo P. Kouwenhoven and Val Zwiller
doi:10.1038/nphoton.2012.110
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.

Large spontaneous emission enhancement in plasmonic nanocavities   pp459 - 462
Kasey J. Russell, Tsung-Li Liu, Shanying Cui and Evelyn L. Hu
doi:10.1038/nphoton.2012.112
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.

Fluctuations and correlations in modulation instability   pp463 - 468
D. R. Solli, G. Herink, B. Jalali and C. Ropers
doi:10.1038/nphoton.2012.126
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.

See also: News and Views by Mussot & Kudlinski

Nanonewton optical force trap employing anti-reflection coated, high-refractive-index titania microspheres   pp469 - 473
Anita Jannasch, Ahmet F. Demirörs, Peter D. J. van Oostrum, Alfons van Blaaderen and Erik Schäffer
doi:10.1038/nphoton.2012.140
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.

Articles

Phase-space measurement and coherence synthesis of optical beams   pp474 - 479
Laura Waller, Guohai Situ and Jason W. Fleischer
doi:10.1038/nphoton.2012.144
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.

See also: News and Views by Testorf

Universal formation dynamics and noise of Kerr-frequency combs in microresonators   pp480 - 487
T. Herr, K. Hartinger, J. Riemensberger, C. Y. Wang, E. Gavartin, R. Holzwarth, M. L. Gorodetsky and T. J. Kippenberg
doi:10.1038/nphoton.2012.127
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.

Terabit free-space data transmission employing orbital angular momentum multiplexing   pp488 - 496
Jian Wang, Jeng-Yuan Yang, Irfan M. Fazal, Nisar Ahmed, Yan Yan, Hao Huang, Yongxiong Ren, Yang Yue, Samuel Dolinar, Moshe Tur and Alan E. Willner
doi:10.1038/nphoton.2012.138
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.

See also: News and Views by Torres | Interview with Alan Willner

Erratum

Speckle-free laser imaging using random laser illumination   p496
Brandon  Redding, Michael A.  Choma and Hui Cao
doi:10.1038/nphoton.2012.162

Interview

A new twist for communications   p498
Interview with Alan Willner
doi:10.1038/nphoton.2012.151
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.

See also: Article by Wang et al. | News and Views by Torres