Laser sets new world record with 12 attosecond pulse

[n2doc]

Lasers can now generate light pulses down to 100 attoseconds thereby enabling real-time measurements on ultrashort time scales that are inaccessible by any other methods.


Ultrashort light pulse with stabilized optical phase. An ultrashort laser pulse is comprised of a few of these oscillations. (red or blue curve).

Scientist at the Max Born Institute for Nonlinear Optics and Short Time Spectroscopy (MBI) in Berlin, Germany have now demonstrated timing control with a residual uncertainty of 12 attoseconds. This constitutes a new world record for the shortest controllable time scale.

Light is an electromagnetic wave of very high frequency. In the visible domain, a single oscillation of the electric field only takes about 1200-2500 attoseconds. Consequently, an ultrashort laser pulse is comprised of a few of these oscillations. However, pulses from conventional short-pulse laser sources exhibit strong fluctuations of the positions of the field maximum relative to the pulse center. For maximum field strength, the center of the pulse has to coincide with a maximum of the electric field, as shown in Fig. 1 as a red curve. Consequently, methods have been developed to stabilize the position of the field maximum, i.e., the phase of the pulse.

Together with Vienna based laser manufacturer Femtolasers, MBI researchers in the group of Günter Steinmeyer have now developed a new method to control the phase of the pulse outside of the laser. In contrast to previous approaches, no manipulation inside the laser is necessary, which completely eliminates fluctuations of laser power and pulse duration and guarantees a strongly improved long-term stability. Correction of the pulse phase relies on a so-called acousto-optic frequency shifter, which is directly driven by the measured signal. Dr. Steinmeyer is convinced: "This direct correction of the phase dramatically simplifies many experiments in attosecond physics and frequency metrology."

http://www.rdmag.com/News/2010/05/Energy-Photonics-Physics-Laser-sets-new-world-record-with-12-attosecond-pulse/

[caraher]

1. Very misleading headline

The pulse is not 12 attoseconds; rather, the jitter in the carrier envelope stabilization of the pulse is only 12 as. The work is a great advance in matching the oscillations of the optical-frequency carrier wave to the peak of the amplitude envelope; but the headline suggests it's the envelope itself that's setting records, which is not what they did (in fact, it appears they're using visible or near-visible wavelengths, when a 12 as pulse would have to be well in the UV).