Postdoc openings!

In our group in King’s College London we study light generation and interaction within nanoscale complex photonic systems, a combination of nano-optics, quantum optics and lasing science.
We are now looking to recruit two postdocs to study:
1. Biocompatible random lasing –  2 year Postdoctoral Research Position (Deadline for applications 13th October 2015)
You will fabricate new disordered biomaterials (biopolymers and proteins such as natural silk) and observe lasing from them, to form the basis of new-generation bio-sensors. For more information go to:
2. Hyperuniform photonic networks – 3 year Postdoctoral Research Position
You will study how single emitters can be controlled and boosted in nanophotonic and hyperuniform networks, combining network theory with nanophotonics, with a view to quantum optics at the nanoscale. This is collaborative project with Dr. Marian Florescu (University of Surrey, UK).
Please contact Dr. Riccardo Sapienza,, for more information.

A new lab to encourage creativity

Creativity is often neglected in academic curricula, mainly because nobody really knows how to teach it. I believe in the “messy play” approach.

I often try to retrace the steps that led to conceiving our scientific experiments and I usually reach the conclusion that it happened when thinking about something else, during periods of intellectual stimulation, often triggered by busy research activity.
As an experimentalist I believe that you need to be making and doing, fiddle in the lab, ask yourself simple questions and link concepts together before you can have that great idea. Creativity escapes traditional frontal teaching (and teacher-centred teaching), instead it requires dirty hands and individual (student-centred) effort.

Wheatstone Innovation LabWith this idea in mind Matthew Howard and I have founded the Wheatstone Innovation Lab, a space for students to experiment, research unsupervised and train their creativity. Named after Charles Wheatstone, the legendary scientist working in King’s College London (in the same lab!) it is designed to promote disruptive thinking. Think about it as the garage where Steve Job and Steve Wozniak invented the first Mac or the shed where Marie Curie discovered radioactivity.

We have been fortunate to be supported by the faculty of natural and mathematical sciences of King’s College London and in particular by Mike and Rosie who strongly believed in this idea, and now we are preparing the first activities: makehatons, researchatons, hackatons!

If you are in King’s check it out here!

Ph.D. position in Nanophotonics of Complex Network

Are you interested in studying the nature of light and how it interacts with nanoscopic bits of matter? We have a Ph.D. opening in our group, in the Physics Department in King’s College London.graphmaze

The project combines network theory with nanophotonics, with the goal of studying how single emitters can be controlled and boosted in nanophotonic networks, towards quantum optics at the nanoscale.

For more information drop me an email: riccardo.sapienza AT



Tuning random lasing in photonic glasses

We have just published a new theoretical model including frequency interaction and mode competition in random lasing which allows to predict resonance-driven tuning of random lasing.   As it builds on solid previous models, we believe that it could be of practical use to predict the behavior of your random lasing system. If you are interested in the code just contact us.

Tuning random lasing in photonic glasses, Michele Gaio, Matilda Peruzzo and Riccardo Sapienza, Optics Letters 2015.

Tuning random lasing in photonic glasses

Random Lasing TuningWe present a detailed numerical investigation of the tunability of a diffusive random laser when Mie resonances are excited. We solve a multimode diffusion model and calculate multiple light scattering in presence of optical gain which includes dispersion in both scattering and gain, without any assumptions about the β parameter. This allows us to investigate a realistic photonic glass made of latex spheres and rhodamine and to quantify both the lasing wavelength tunability range and the lasing threshold. Beyond what is expected by diffusive monochromatic models, the highest threshold is found when the competition between the lasing modes is strongest and not when the lasing wavelength is furthest from the maximum of the gain curve.

PDF available here: Tuning random lasing in photonic glasses

The freelance postdoc experiment

We are all well aware of how difficult is to get a permanent position in academia. The employers are very cautious as the tenured position comes with a very strong contractual stability and in some country with immortality (as civil service status). The postdocs work longer and longer hours to face the increasing competition. Academia needs more and more advanced skills that can only be acquired with years of experience but it refrains from rewarding it with a permanent job. An interesting alternative is that of the academic freelancer as proposed by Katie Rose Guest Pryal here, as a mean to alleviate the intense and extenuating life of a postdoc or not-tenured academic.


We have already started such an experiment, as I have hired a recently graduate and unemployed colleague to perform some theoretical calculations that we need for our experiments. The difference with respect to a normal collaboration is that this time I am paying him by the hour and he is performing the work choosing his time and without being based in London, just coming for a meetings to discuss the results. All the other discussions are done by Skype, email and probably soon in Slack.

In this way we can reward skills and actual hours of work, and potentially we can resolve personal issues such as family relocation etc… Would this work also for experimental work? It is hard to tell, but I could imagine having a setup in my house and performing experiments on demand as a freelancer does. Shared facilities similar to maker and hacker space could also make lab space and equipment more accessible.

Sooner or later we will have to invent a new way to develop science, a research 2.0, and it may start by embracing new concept such as remote and freelance work.


Logos for science projects – NQO COST Action

Here some test for the logo of our COST Action on Nanoscale Quantum Optics that will start shortly.

cubed NQO Cost Action

Together with Andrè Xuereb we have produced this first logo. I like that it highlights that nanotechnology deals with the constituent of matter down to the nanoscale. In particular nanophotonics is the science of light (hence the colour) coming from nano-structuring and nano-optics.
Moreover, inspired by the previous logo of the MIT medialab our logo can be made slightly different for each use, as the complex colour pattern can be modified to be unique with a large set of combinations available.

Technically, I have used Cinema4D with the script voxel from

Will post also the next iteration shortly, any comment welcome.


I got various comments, so I have decided to change the style. Here the new versions…

more squared

logo_NQO_coloured2 logo_NQO_simple2

more rounded

NQO coloured



A physicist at the Biennale di Venezia

Last week I had the chance to discuss colours from a nanophotonics point of view, at a meeting about Fundamentals of Space: Colour and Line organised at the Biennale of Architecture, and invited by the energetic Ivana Wingham.
I am always fascinated by cross-contamination like these, and despite the large differences in method and language (my first live performance of dance and art during the talks) nothing brings more new ideas than talking to the other side of the brain, to a different audience. Very often we risk of forgetting the world outside the lab, as we put so much efforts in solving the scientific puzzles, and events like these bring me back to real life.
I really enjoyed learning about colour in architecture, to form space, to affect our brain. I also discovered interferential painting done by coated mica crystals, much more interesting than titanium dioxide powders! Still nothing from Mie resonators or plasmonic particles though…
Will this start a new architectural-artistic-scientific project? Will keep you posted.
Fundamentals of Space: Colour and Line

Percolating Plasmonic Networks for Light Emission Control

After a long time we have complete our study of plasmonic networks and how they control the fluorescence decay rate of individual nano-sized emitters. Here below links and abstract.

Plasmonic networksPlasmonic networks

Link to the paper:  Faraday Discussions, 2014, DOI: 10.1039/C4FD00187G

Abstract: Optical nanoantennas have revolutionised the way we manipulate single photons emitted by individual light sources in a nanostructured photonic environment. Complex plasmonic architectures allow for multiscale light control by shortening or stretching the light wavelength for a fixed operating frequency, meeting the size of the emitter and that of propagating modes. Here we study self-assembled semi-continuous gold films and lithographic gold networks characterised by large local density of optical states (LDOS) fluctuations around the electrical percolation threshold, a regime where the surface is characterised by large metal clusters with fractal topology. We study the formation of plasmonic networks and their effect on light emission from embedded fluorescent probes. Through fluorescence dynamics experiments we discuss the role of global long-range interactions linked to the degree of percolation and to the network fractality, as well as the local near-field contribution coming from the local electro-magnetic field and topology. Our experiments indicate that local properties dominate the fluorescence modification.

Royal Society

Slack for science

Is the right collaborative tool for science?

slack-logoI have just start to test its capabilities.  My hope is that it will combine many platforms and separated tools into one organic, searchable and multi-platform service.
For scientific research I now use Dropbox for file sharing, Googledocs and Sharelatex for article writing, Papers for article management, Evernote for notes and Wonderlist for tasks, plus the usual various chats, Twitter and Skype for remote discussions. Still I keep  wasting time searching for files and bits of discussion lost here and there.

Slack holds great potential as it merges all communication tools in a single clean workspace, hosted on the clouds, linked to all the other services (e.g. dropbox, Github or Googledoc) with excellent notification (which could still be improved). I especially like the ease of use mobile, browser and standalone app, and the file management with good searching tools. Code can also be inserted with syntax highlighting by simply hitting ⌘ + ⏎.

All these features are very promising but will it survive the everyday use of our research team?

A glance into crystallisation

Macroscopic systems such as hard micrometer beads can undergo crystallisation in a way similar to atoms in our conventional crystals. The larger size means that we can observe the crystallisation process under the microscope, and be mesmerised by it:

As a technical note, after some time you can see how the crystal self-heal its defects as the hexagonal packing is the least energy configuration. The video is in real time (1 frame/5 sec) and the apparent jump is due to the structure changing not to video editing.