Although still in its build-up phase, the Unilase project has already produced results that are attracting strong attention, including more than ten invited talks at leading scientific conferences and several publications. The progress so far includes two fundamental advances on the path to second mode-locking, as well as two practical demonstrations of the power of collective interactions between many ultrafast pulses.
As a first conceptual step, we addressed a long-standing puzzle: why do lasers with multiple pulses inside their cavities tend to be unstable? We discovered that their relative positions shift randomly, much like the jittery motion of pollen grains suspended in water, known as Brownian motion. In that case, the grains move because of collisions with atoms; in lasers, the pulses move because of randomly emitted photons dictated by the laws of quantum physics. With this new understanding, we were able to stabilise such lasers and bring their performance close to that of conventional mode-locked systems.
A second breakthrough followed from tackling the question of how pulses can be created and organised into a coherent population. Here we drew inspiration from biology, where living organisms achieve order through hierarchical self-organisation—structures built within structures. By applying this principle across time, we showed how to organise many pulses in a controlled and stable way.
With these foundations in place, we are now constructing a new laser system to attempt the first demonstration of second mode-locking. The outcome will reveal whether this bold concept can be realised in practice.
In parallel, we have also explored the collective effects of high-repetition-rate pulses. Preliminary experiments show supersonic material removal for the first time. In addition, in collaboration with other researchers, we demonstrated a tiny ultrafast chemical reactor, created momentarily within a liquid by focusing laser pulses. The reactor drives fluid motion that circulates the entire container, which is about a billion times larger than the reactor itself, so that every portion of the liquid briefly reaches thousands of degrees for just a millionth of a second. This enables unique chemical pathways, and using this approach we succeeded in synthesising previously unattainable types of zeolites, an important class of catalysts.
