Volume 3 Issue 10, October 2009

The race to demonstrate new lasers, including electrically pumped polymer lasers, makes it a good time to reflect on the measurements that must be undertaken to support a claim of lasing.

Strain gauges that change colour when stressed, bright backlight-free displays and highly sensitive biological sensors are all potential applications of tunable photonic crystal materials, reports Duncan Graham-Rowe.

Accurate frequency measurements of a narrow optical clock transition in ¹⁷¹Yb atoms trapped in an optical lattice establish this system as a serious contender in the quest to develop increasingly accurate atomic clocks.

Interconnects and switches relying on excitons — quasiparticles consisting of bound electron–hole pairs — may offer a promising energy-efficient alternative to electrons in wires for future electronic circuitry.

The news that spherical droplets of a liquid crystal can function as whispering-gallery-mode microresonators with an unprecedented width of wavelength tunability could be good news for fabricating new kinds of sensors and lasers.

The use of cascaded nonlinear silicon waveguides that function as 'time lenses' is providing new opportunities for generating and measuring ultrafast optical waveforms.

Could hexagonal boron nitride turn out to be the answer for a practical and compact source of deep-ultraviolet light? Although initial results are promising, the challenge for the future is in improving the fabrication technology.

High-resolution microscopy, lithography and materials analysis all look set to benefit from the emergence of compact and efficient table-top soft-X-ray lasers.

Semiconductor nanowires, by definition, typically have cross-sectional dimensions that can be tuned from 2–200 nm, with lengths spanning from hundreds of nanometres to millimetres. These subwavelength structures represent a new class of semiconductor materials for investigating light generation, propagation, detection, amplification and modulation. After more than a decade of research, nanowires can now be synthesized and assembled with specific compositions, heterojunctions and architectures. This has led to a host of nanowire photonic devices including photodetectors, chemical and gas sensors, waveguides, LEDs, microcavity lasers, solar cells and nonlinear optical converters. A fully integrated photonic platform using nanowire building blocks promises advanced functionalities at dimensions compatible with on-chip technologies.

Exciton optoelectronic devices have been demonstrated previously at an operating temperature of 1.5 K. Here, experimental proof-of-principle for excitonic switching devices at approximately 100 K is demonstrated. Excitonic devices promise high operation speed and optoelectronic integration in compact dimensions.

By exploiting the nonlinearity of on-chip silicon nanowaveguides, a parametric temporal imaging system that can compress optical waveforms in time is demonstrated, enabling generation of complex and rapidly updatable ultrafast optical waveforms.

A terahertz quantum cascade laser that uses a grating etched into a double-metal waveguide to greatly improve the laser's performance is reported. The grating enhances the laser's optical power extraction and provides control over its emission wavelength and beam quality, yielding a single-mode beam that has a divergence of less than 10 degrees in both axes and a power of up to 15 mW.

A handheld and battery-operated far-ultraviolet plane-emission device is demonstrated. The device has low current consumption and stable operation at an output power of 0.2 mW at 225 nm, and may be useful in photochemical and biotechnological applications such as photo catalysis, sterilization and the modification of chemical substances.

Whispering-gallery-mode resonators made of nematic liquid-crystal droplets offer a wavelength tunability approximately two orders of magnitude larger than that of conventional solid-state microresonators.

Analysis of the spectral content of light is important in countless applications, ranging from biomedicine to material analysis and product quality control, reports Neil Savage.

Until now, excitonic devices have only been realized at temperatures of 1.5 K. Nature Photonics spoke to Leonid Butov from the University of California in San Diego about his group's recent demonstration of excitonic switches operating at 125 K.