On Monday August 18 we learned that our former colleague, Prof. dr. J.P. (Han) Woerdman passed away after a prolonged illness at the age of 77

In 1968 Han's scientific career started at the Philips Resaerch Laboratories in a period that it was still possible to do fundamental research there. When in 1983 at Philips the winds of change picked up speed, he decided to leave and to join the Leiden Faculty as a Full Professor of Experimental Physics. Initially, he worked on topics that were closely connected with his work at Philips. Quite soon after his arrival he scored a first hit with the demonstration of the optical piston. Soon afterwards he changed gears by initiating a research effort in Laser Physics, in particular, regarding the fundamental linewidth of a laser. This requires the use of lasers with high gain and low-reflectivity mirrors or unstable cavities. Simultaneously, he initiated  a research line in the field of semiclassical optics with questions like: "Can one rotate an atom?" Together with his students he showed that all of the two-level coherent quantum physics can be mimicked in a fully classical optical cavity. This work led, among others, to the discovery of the orbital angular momentum of light, possibly the work he is most famous for. Han realized that all this work was not truly quantum in the sense that the radiation field was purely classical. Subsequently, he enticed his colleagues to co-embark on true quantum optics and to study quantum entanglement, resulting in a plethora of publications on this topic. At the end of his career in Leiden he changed gears again, returning to classical optics and his long-lasting love for systems exhibiting a non-local optical response.

Han knew his literature and his topics incredibly well. He loved to pose (and answer) fundamental questions but disliked complicated experiments.
He was exceedingly meticulous, spending lots of time on any manuscript that was to be submitted as well on the writing of research grants. In that, he was, in his time, an absolute master and absurdly successful.

Han was a very private person who did things basically on his own whenever he could. In the areas where he felt more insecure, he was happy to let others help him. When in 2010 he got ill with Parkinson's disease he kept us all in the dark. This disease, which eroded his enormous intellectual abilities, led to his recent death.

We mourn the loss of a great Leiden physicist and a well-respected colleague.