A new method for generating controllable optical pulse pairs using a single fiber laser

Researchers from Bayreuth University and Konstanz University are developing new methods to control ultra short laser emission 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 lasers is set by dividing each pulse into two pulses and delaying them at different, mechanically adjustable distances. Alternatively, a laser source with slightly different orbital periods ("double comb") can be used to generate rapid travel delay from the superposition of two pulse combs.

Professor Georg Herink, the head of the ultrafast dynamics research team for Experimental Physics VIII at Bayreuth University, and his doctoral students Julia A. Lang, along with Professor Alfred Leinstorfer and Dr. Sarah R. Hutter from the University of Constance, have collaborated 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, glass fiber based light sources. By temporarily merging the two pulse combs outside the laser, researchers have obtained a pulse mode that can be set with any delay as needed.

Schematic diagram of dual comb fiber laser oscillator, external pulse combination, and real-time detection.

The researchers used a technique: instead of the usual single light pulse, two pulses are cycled in the laser. The first author of the study, Lang, explained, "There is enough time between two pulses to apply a single" interference "using the fast optical switch inside the laser. Using the knowledge of laser physics, this" intracavity modulation "can cause changes in pulse velocity, causing the two pulses to offset each other in time." The laser source based on glass fiber is manufactured by Hutter and Leitenstorfer from the University of Konstanz.

Thanks to special real-time measurement methods, researchers at Bayreuth University can now accurately observe how short light pulses (called solitons) move when subjected to external influences. This real-time spectral interferometry technology can accurately measure the distance between each pair of pulses - over 10 million times per second. Herink explained, "We have demonstrated that we can adjust time extremely quickly on a large scale and achieve freely programmable forms of motion.". They proposed an innovative method for controlling solitons, which not only provides new insights into soliton physics, but also opens up possibilities for the particularly fast and efficient application of ultra short laser pulses. The research findings have been published in the journal Science Advances.

Source: Laser Manufacturing Network