Volume 4 Issue 10, October 2010

Researchers have demonstrated how photon correlations can be used to explore the spectral diffusion of light from a single quantum dot with subnanosecond time resolution. This will help to clarify the origin of frequency jitter, and thereby help to realize narrowband stable condensed matter sources of single photons.

The realization of an all-optical phase and amplitude regenerator could help take coherent optical communication to new distances and transmission speeds.

High-harmonic interferometry can be used to measure the amplitude and phase of light emitted from molecules. This method has now been used to reveal the ultrafast dynamics of electrons and nuclear interactions during a chemical reaction.

Research into photochemical reactions is now yielding promising ways of converting solar energy into convenient forms of chemical energy that can be easily stored.

Graphene has had a big impact in optics and optoelectronics for both fundamental physics and real-world applications, and there is now considerable excitement about its prospects for terahertz science.

Wide-band tunability, large coherence-area, and in some cases multidirectional emission have made liquid-crystal lasers an attractive light source for applications like miniature medical diagnostic tool and large-area holographic laser displays. This article discusses the scientific origins of the technology of liquid-crystal lasers and reviews the current cutting-edge research.

By using bright pulses of light to ‘blind’ the avalanche photodiode detectors used in quantum cryptography equipment, scientists in Europe have shown that it is possible to tracelessly steal the secret encryption key generated by such systems and thus compromise their security.

Devices that can reduce noise in fibre-optic communications systems are of great technical importance. Scientists have now developed a practical all-optical regenerator that is capable of directly removing not only amplitude noise but also phase noise from binary phase-encoded optical communications signals.

Optical spectral broadening prevents access to intrinsic physical phenomenon. A new experimental technique is demonstrated for measuring spectral diffusion based on photon correlations within a spectral line. The time resolution of the photoluminescence was 90 ps, which exceeds the current best reported resolution by four orders of magnitude.

The effect of loss on quantum states is one of the major hurdles in quantum communications. A quantum error-correcting code that overcomes erasure due to photon loss is experimentally demonstrated. The scheme uses linear optics and protects a four-mode entangled mesoscopic state of light.

Coherent Rabi flopping and coherent pulse reshaping are directly observed in an operating quantum cascade laser. The findings indicate the potential for coherent effects to be exploited in mode locking, and may stimulate new approaches for generating short pulses in quantum cascade lasers.

Researchers demonstrate random-number generation by exploiting the intrinsic randomness of vacuum states. The approach may lead to reliable and high-speed quantum random-number generators for applications ranging from gambling to cryptography.

Scientists improve the precision of time-of-flight measurements from several hundreds of micrometres to the nanometre regime by timing femtosecond pulses through phase-locking control of the pulse repetition rate using the optical cross-correlation technique. This result looks set to benefit synthetic aperture imaging for future space missions of formation-flying satellites and remote experiments involving the general theory of relativity.

The effects of interactions on Hanbury Brown and Twiss interferometry are studied by considering the propagation of light in a nonlinear optical medium. The interactions affect the multipath interference, which makes it difficult to extract information about the light source. Nevertheless, the recovery of the disordered information is demonstrated through proper analysis.

Using high-frequency sound waves to make tunable optical filters, modulators and Q-switches is a well-established and convenient technological solution for many applications, reports Neil Savage.

A regenerator capable of simultaneously removing both phase and amplitude noise from an optical data stream may be a critical component of future optical networks. Radan Slavík explained to Nature Photonics how he and his co-workers realized such a device.