Researchers found a way to take photos of light pulses, Today’s lasers can produce very short pulses of light that can be used for a variety of applications from research materials to medical diagnoses.
For this purpose, it is important to measure the waveforms of the laser beam with high accuracy. Until now, this had required large and complex experimental arrangements. now the researchers found a way to take photos of light pulses.
This can now be done with miniature crystals with a diameter of less than one millimeter. New method developed. Progress will already help explain important details about the interaction of light and matter.
Very short pulses of light with a duration of femtoseconds (10-15 seconds) are examined.
The reaction of electrons to the laser’s electric field gives us very precise information about the shape of the pulses of light.
Until now, the usual method for measuring infrared laser pulses was adding laser pulses with much shorter wavelengths to the X-ray region. Both impulses are transmitted through gas. X-ray pulses ionize each atom and release electrons, which are then accelerated by an electric field from an infrared laser pulse, to take photos of light pulses.
Electron movements are recorded, and if the experiment is repeated several times with different time shifts between the two pulses, the shape of the infrared laser pulse can be reconstructed.
To avoid such complications, the idea was born to measure pulses of light not in gases but in solids: “In gases, you must first ionize atoms to get free electrons. “In solids, it is enough to give electrons enough energy so that they can move through solids, driven by laser fields,” said Isabella Floss (Vienna University of Technology).
This creates an electric current that can be measured directly.
Small silica crystals with a diameter of several hundred micrometers are used for this purpose. They are shocked by two different laser pulses: The pulse to be tested can have any wavelength, ranging from ultraviolet light to visible colors and long infrared waves. When this laser pulse penetrates the crystal, another infrared pulse is fired at the target.
This second impulse is so strong that the nonlinear effect on the material can change the energy states of the electrons so they move.
Once the electrons can move through the crystal, they are accelerated by the electric field of the first beam. This creates an electric current that is measured directly in the crystal.
This signal contains accurate information about the shape of the light pulse.
The waveforms of light pulses can now be measured far more easily than before with a much simpler and more compact design.
The new method opens many interesting applications.
It should be possible to characterize new materials appropriately, answer basic physical questions about the interaction of light and matter, and even analyze complex molecules in order to, for example, be able to reliably and quickly detect disease from small blood samples.