Physicists in Germany say they have taken an important step towards the creation of ultrafast computers that use light instead of electrical signals to process information. The team has created the first compact electronic device that can measure the absolute phase of extremely short light pulses. While the device is first expected to find use in laser labs, it could someday play an important role in systems that use ultrashort light pulses to process information.
The work was done by Ferenc Krausz and colleagues of the Max Planck Institute of Quantum Optics in Garching. In 2001 a team led by Krausz and colleagues generated and measured the first isolated light pulse lasting only attoseconds – just a billionth of a billionth of a second. Such pulses have since been used to study the motion of electrons inside atoms and they form the basis of the new and burgeoning field of "attosecond physics".
While the technology used to create and characterize these pulses has improved over the past decade, it still involves the use of large and expensive pieces of equipment. This includes the techniques used to make absolute phase measurements, which are essential for understanding rapidly varying optical signals. Although there are many techniques for sensing relative changes in light phase, measuring its absolute value (relative to a standard) is a challenge for visible-light pulses. Currently, there are techniques available – attosecond streaking and stereo above threshold ionization (ATI) – but both methods require high-vacuum conditions and large amounts of physical space, making them unsuitable for deployment on a tiny device.
taken from http://physicsworld.com/cws/article/news/2014/jan/17/ultrafast-phase-measurements-could-boost-optical-computing.
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