Always on beat: Ultrashort flashes of light under optical control

Laser pulses have long been utilized in research laboratories, industrial production, and medical therapies. In these applications it is often crucial that the pulses -- also known as optical solitons -- occur at certain intervals. Using a special high-speed measurement technique, the researchers were able to show how a short-pulse laser widely applied in research can be made to automatically generate pairs of light pulses separated by the desired interval. All that is required are small disturbances in the green "pump beam" (which generates the laser pulses) triggered by electric signals.

The new process centres on the targeted manipulation of solitons, wave packets that can occur in pairs in ultrashort laser pulses. "The resonance excitation and the short disturbance of soliton pairs trigger effects that can be used to specifically control ultrashort laser pulses. This opens up an exciting new area of research with a yet unforeseeable range of possible applications," said Professor Georg Herink from the University of Bayreuth, corresponding author of the new study.

"At the right frequency, a tiny external modulation of the laser is all you need, and ultrashort laser pulses are set into reciprocal, resonant oscillation. Similar phenomena can be observed in water molecules heated in the microwave," added lead author Felix Kurtz from the University of Göttingen. The newly published findings show that in the future, ultra-short pulse lasers will not only be considered as a tool, but also remain a fascinating object of research.