Researchers have gotten a step closer to being the masters of waveforms from pulsed laser light.
A research team built a "simplified detector" that allowed them to measure the waveforms; the device paints a clear picture of the quick pulses that last only a few femtoseconds, a Max-Planck Institute news release reported.
This new method goes above and beyond modern gas-phase detectors. It is made of glass and measures "the flow of electric current between two electrodes that is generated when the electromagnetic field associated with the laser pulse impinges on the glass," the news release reported.
"The researchers can then deduce the precise waveform of the pulse from the properties of the induced current," the news release reported.
Discovering the precise waveform of the femtosecond pulse could help researchers create light flashes that are thousands of times shorter (only a few attoseconds). Today's mode-locked lasers can generate pulses as short as 2.5 femtoseconds.
"Such pulses correspond very few oscillations of the electromagnetic field, indeed to only one to two complete cycles, which are however preceded and followed by waves of lower amplitude that are rapidly attenuated," the news release reported.
Looking at the high-amplitude oscillations allow researchers to determine the shape of the electromagnetic fields so they can be used to "probe ultrashort processes that occur at the level of molecules and atoms."
This new glass-based detector allows researchers to easily determine the wave shapes that make up a specific femtosecond pulse. The team's experiments have taught them that pulsed high-intensity laser light "impinges" on glass. The team found that the "direction of [electric] flow of the current generated by an incident femtosecond pulse is sensitively dependent on the exact form of its wave packet," the news release reported.
The team paired up their device with a common instrument that measures waveforms of light, which gathers its information from free electrons; this type of measurement must be conducted in a vacuum. In their comparison the team found the new device "simplifies measurements in the domain of ultrafast physical processes" and does not need to be used in a vacuum.
"Highly sensitive and reliable measurements of physical processes at the level of the microcosmos with the aid of single attosecond light flashes of known shape should become easier to perform because, thanks to the new glass-based phase detector, the source of the energy to drive them - the waveform of the laser pulses - can now be controlled much more easily than before," the news release reported.
