Always In The Right Time: Ultra-Short Flashes Of Light Under Optical Control

Ultra-short laser flashes allow high-precision material analysis and medical procedures. Physicists from the University of Bayreuth and the University of Göttingen have now discovered a new method for how minute time intervals between laser flashes can be changed very quickly and exactly. At the touch of a button, the distances can be increased or decreased as needed. The potential applications range from laser spectroscopy to microscopy to material processing. The researchers present their new findings in the journal Nature Photonics.

Laser flashes of light have long since found their way from research laboratories to industrial manufacturing and medical therapies. In these applications it is often crucial that the flashes - also known as optical solitons - follow one another at certain intervals. Using a special high-speed measuring technique, the researchers were now able to show how a widely used short-pulse laser can be used to automatically generate pairs of light pulses at the respectively desired distance. Small, triggered by electrical signals disturbances in the green "pump beam", which generates the laser pulses, are sufficient for this.

The core of the new process is the targeted influencing of solitons. These are packets of light waves that can be bundled in pairs in ultrashort laser flashes. "Resonance excitation and short perturbation of soliton pairs trigger effects that can be used to selectively control ultrashort laser pulses. This opens up an exciting new field of research with an incalculable range of possible applications, "says Prof. Dr. med. Georg Herink from Bayreuth, corresponding author of the new study. "At the right frequency, a tiny external modulation of the laser is sufficient, and ultra-short laser pulses get into a mutual resonant oscillation. We know similar phenomena of water molecules in the microwave, "adds first author Felix Kurtz from Göttingen.