On demand ultra short laser flash: controllable optical pulse pairs from a single fiber laser

Set up a dual comb fiber laser oscillator, external pulse combination, and real-time detection.
In innovative methods for controlling ultra short laser flashes, researchers from Bayreuth University and Konstanz University are using soliton physics and two pulse combs in a single laser. This method has the potential to greatly accelerate and simplify laser applications.

Traditionally, the pulse interval of a laser is set by dividing each pulse into two pulses and delaying them at different mechanically adjustable distances. Alternatively, two laser sources with slightly different orbital periods ("double combs") can be used to generate rapid travel delays from the superposition of two pulse combs.

Professor Georg Herink, the leader of the Experimental Physics VIII - Ultra Fast Dynamics group at Bayreuth University, and his doctoral student Julia A. Lang collaborated with Professor Alfred Leinstorfer and Sarah R. Hutter from the University of Constance to demonstrate a pure optical method based on two pulse combs in a single laser. It can achieve extremely fast and flexible adjustable pulse sequences.

Meanwhile, this can be achieved in very compact fiberglass light sources. By combining two pulse combs outside the laser, researchers have obtained a pulse mode that can be set with any delay as needed.

The researchers used a technique: two pulses circulate in the laser instead of the usual single light pulse. "There is enough time between two pulses to apply a single 'interference' using the fast optical switch inside the laser," explained Lang, the first author of the study. "Using laser physics, this' intracavity modulation 'causes a change in pulse velocity, causing two pulses to move towards each other in time."

The laser source based on fiberglass was built by Hutter and Leitenstorfer from the University of Constance. Thanks to a special real-time measurement method, researchers at Bayreuth can now accurately observe how short light pulses (called solitons) move when external influences act on them. This real-time spectral interferometry method can accurately measure the distance between each pair of pulses - over 10 million times per second.

"We have demonstrated that we can quickly adjust time over a wide range and achieve freely programmable motion forms," explained Herink. The research now published in Progress in Science proposes an innovative method for controlling solitons, which not only provides new insights into soliton physics, but also opens up possibilities for the rapid and efficient application of ultra short laser pulses.

Source: Laser Net