Volume 7 Issue 11, November 2013

Nanotubes and graphene have emerged as promising materials for use in ultrafast fibre lasers. Their unique electrical and optical properties enable them to be used as saturable absorbers that have fast responses and broadband operation and that can be easily integrated in fibre lasers.

Nature Photonics spoke to Anatoly Grudinin, founder of the fibre laser company Fianium, to gain insight into the vicissitudes in the industry over the past decade and future challenges that academia can help solve.

Silicon-waveguide-integrated graphene photodetectors offer high responsivities, high speeds and broad spectral bandwidths, paving the way for graphene-based optical interconnects.

The Italian free-electron laser, FERMI, now generates coherent soft X-rays in the water window (2.3–4.4 nm) by two-stage frequency upconversion of ultraviolet seed laser pulses using the 'fresh bunch' technique.

Squeezed light allows quantum limits to be overcome in precision metrology. A new way of producing this special form of light has now been demonstrated by engineering the vibrations of nanostructured optical cavities.

Massive objects in space act as gravitational lenses, bending and focusing light. Scientists have now created a photonic analogue of a gravitational lens on a chip, and have shown that it is strong enough to force light into orbits.

The integrated optical components used for optical data transmission are technically complex. To keep pace with the exponential growth in communication traffic, researchers are exploring every potential avenue for inexpensively enhancing device performance.

High-power fibre lasers are in demand for industrial, defence and scientific applications. This review provides an overview of the present state of the art in the field and discusses present challenges and the future outlook.

Ultrafast fibre lasers are an important optical system with industrial, medical and purely scientific applications. Essential components and the operation regimes of ultrafast fibre laser systems are reviewed, as are their use in various applications.

This Review discusses recent advances, and identifies challenges and opportunities regarding the use of fibre lasers in nonlinear bioimaging.

A chip-integrated graphene photodetector with a high responsivity of over 0.1 A W⁻¹, high speed and broad spectral bandwidth is realized through enhanced absorption due to near-field coupling. Under zero-bias operation, response rates above 20 GHz and an instrumentation-limited 12 Gbit s⁻¹ optical data link are demonstrated.

A CMOS-compatible graphene/silicon-heterostructure photodetector formed by integrating graphene onto a silicon optical waveguide on silicon-on-insulator and operating in the near- and mid-infrared regions is demonstrated. A responsivity as high as 0.13 A W⁻¹ is obtained at a bias of 1.5 V for 2.75-μm light at room temperature.

A CMOS-compatible photodetector based on graphene with multi-gigahertz operation ranging from the O- to U-band of telecommunication bands is demonstrated, highlighting the promise of graphene as a new material for integrated photonics.

A simple, rapid and inexpensive nanolithography technique is demonstrated that exploits nonlinear feedback mechanisms to tightly regulate the formation of nanostructures induced by femtosecond laser pulses. The nonlocal nature of the feedback allows the nanostructures to be seamlessly stitched, resulting in large-area nanostructuring whose periodicity is uniform on a subnanometre scale.

By utilizing a microstructured optical waveguide around a microsphere, an optical anlogue of the effects of gravity on the motion of light rays is demonstrated. Both far-field gravitational-lensing effects and the critical phenomenon that occurs close to the photon sphere of astrophysical objects under hydrostatic equilibrium are experimentally demonstrated.

Silver and silicon nitride metamaterial structures with dielectric permittivities close to zero are demonstrated at visible wavelengths. In such materials, the optical phase advance during propagation can be very small.

A seeded free-electron laser with a two-stage harmonic upshift configuration provided tunable and coherent soft-X-ray pulses. The configuration produced single-transverse-mode, narrow-spectral-bandwidth femtosecond pulses with energies of several tens of microjoules and a low pulse-to-pulse wavelength jitter at wavelengths of 10.8 nm and below.

The self-organization of many laser modes in phase and frequency realized by minimizing radiation losses in a cavity enables the complex wavefront required to focus light scattered by turbid samples to be generated on sub-microsecond timescales without employing electronic feedback, spatial light modulators or phase-conjugation crystals.

Tamm states on subwavelength, reconfigurable plasmonic crystals are studied in the terahertz regime. By introducing an independently controlled plasmonic defect, an electromagnetically induced transparency phenomenon is revealed.

Researchers have fabricated a voltage-tunable plasmonic crystal in a two-dimensional electron gas that operates at terahertz frequencies. Nature Photonics spoke to Eric Shaner, Greg Dyer and Greg Aizin about the observation of Tamm states at the crystal's edge.

Thanks to recent developments, lasers based on fibre media with gain are simple, reliable and cost effective. Topics covered in this focus include high-power sources, ultrafast fibre lasers, industry's perspective on the developments in the field over the past decade, applications such as biomedical imaging, and nanotube- and graphene–based saturable absorbers for fibre lasers