LENS (Florence, Italy)
Laboratorio Europeo di Spettroscopie Non Lineari
LENS, the European Laboratory for Non-Linear Spectroscopy, is a center of excellence at the University of Florence. Research interests include photonics, biophysics, chemistry and atomic physics. Three different main research areas (BIOPHOTONICS, PHOTONIC MATERIALS, ATOMIC PHYSICS) and more than twenty research topics, corresponding to active laboratories, are presently running.
Website: www.lens.unifi.it
Contact:
Lucia Gardini
Mariangela Di Donato

Research highlights
Cold Matter
- Study of quantum vortices in strongly correlated Fermi superfluids: new experimental protocols for the creation and manipulation of single quantized vortices [Nature 600, 64 (2021); Nat. Phys. 20, 939 (2024)]
- Study of quantum transport Hamiltonians in ring optical potentials: investigation of persistent currents in atomic annular superfluids [Phys. Rev. X 12 (2022); Nat. Commun. 15 (2024)]
Spectroscopy
- Visible light driven molecular motors (Access from Stratingh Institute for Chemistry, Groningen, 2022): We present a class of visible-light-driven molecular motors based on barbituric acid. Using a combination of femto- and nanosecond transient absorption spectroscopy, molecular dynamics simulations and low-temperature 1H NMR experiments we found that these motors operate similarly to push-pull second-generation overcrowded alkene-based molecular motors showing a high predicted quantum yield of isomerisation (68%) occurring on the sub-ps timescale [Chemical Science 14, 8458 (2023)].
Biophysics and Biophotonics
- RAPID is a real-time autofocus method for widefield microscopes that ensures high resolution in large volumes. It enables detailed 3D analysis of mouse brains and is versatile across various imaging applications, including in vivo and fast organism tracking. [Nature Methods, 18(8), 953-958].
- By means of Ultrafast Optical Tweezers it is possible to study enzyme/substrate interaction of single molecules under constant load with a unique temporal resolution, in the scale of the microsecond. These techniques have been applied to the study of the interaction of adaptor protein alpha-catenin with actin. Alpha catenin is one of the key protein sensing mechanical stimuli and the cell-cell junction, for this reason understanding how it reacts to endogenous forces is extremely important. [Nature communications 13.1 (2022): 1146]
Photonics in Complex and Soft Matter
- Complex matter is typically composed of nano- and microstructures that determine the structural and dynamic properties of the material at the macroscopic scale, as well as many interactions between these materials and electromagnetic waves. At LENS, we investigate the structure and dynamics of soft matter using time-resolved laser spectroscopy and exploring photonic phenomena arising from the disordered nature of these materials. Recently, a solution of dye molecules and TiO nanoparticles has been used to generate a random laser source, enabling the exploration of innovative spectroscopic applications of this unconventional laser source for performing spectral super-resolution analysis. [Nature Photonics, 14,177 (2020)]
High pressure science
- Direct synthesis and characterization of crystalline carbonic acid from water and carbon dioxide [Angewandte Chemie – International Edition, 63, 22, e202403953 (2024)].
- Discovery of an exotic crystalline antimony nitride by direct HP HT synthesis from elements [Angewandte Chemie – International Edition, 63, 11, e202319278 (2024)].
- High-pressure synthesis and characterization of af a new kind of monodimensional low-bandgap polymer embedded in diamond-like carbon nanothreads [Chemistry of Materials,34, 5, 2422 (2022)].
Expertise
LENS was born as a European scientific research centre providing advanced laser, spectroscopic and microscopy facilities for researchers from European countries, promoting and facilitating the exchange of ideas, scientific techniques, and technical skills. From atomic physics to photochemistry, biochemistry and biophysics, from material science to photonics and to solid and liquid state physics, all of these fields share the same fundamental methodology: the use of laser light to investigate and manipulate matter.
Picture of a typical custom-made setup for non-linear optics at LENS. Credits to Renato Torre.
At LENS we propose several different facilities in cutting-edge research:
- Single-molecule localization microscope: 3D tracking and super-resolution, 2D Single Molecule Tracking
- Ultrafast force-clamp spectroscopy (Optical Tweezers)
- Optical tweezers and fluorescence microscopy in cells
- FRET microscopy
- Light-sheet microscopes: for imaging of cleared tissue and of zebrafish; for high-throughput, high-speed and high-resolution 3D imaging
- Fluorescence Lifetime & SHG Imaging: Multimodal non-linear, FLIM, and Raman microscope; Fluorescence lifetime imaging probe
- Laser-scanning microscopes: two-photon microscope, three-photon microscope, confocal microscope, microRaman microscope
- Aperture-type Scanning Near-field Optical Microscope
- Scattering-type Scanning Near-field Optical Microscope
- Low-temperature and time resolved confocal microscope
- Pump-probe experiment based on two femtosecond lasers with locked cavities enabling Asynchronous Optical Spectroscopy
- Time-resolved Transient Grating Experiments and Optical Kerr Effect, based on picosecond or femtosecond laser pulses
- Time-Domain Spectroscopy with Pulses from THz to UV, based on femtosecond laser conversion, including multidimensional spectroscopy
- one- and two-photon fluorescence spectroscopy under varying pressure conditions, utilizing picosecond visible and UV laser pulses to investigate electronic structures.
- one- and two-photon fluorescence spectroscopy under varying pressure conditions, utilizing picosecond visible and UV laser pulses to investigate electronic structures.
- Powder X-ray diffraction as a function of pressure for the determination of crystal structures and the characterization of phase transitions.
- Diamond anvil cell (DAC) technology, including cryo-loading and spray loading techniques; synthesis of exotic materials and exploration of high-pressure and high-temperature phase diagrams.
- Two-photon direct laser writing (NanoScribe GmbH)
- Ultracold Quantum Matter Laboratories
- Light for quantum technologies
Equipment offered to external users

Super-resolution image of the actin cortex of an eucaryotic cell. The image is obtained by staining F-actin with a photoactivable fluorescent probe that is localized with nanomemter precision. This technique allows to image subcellular structures at a resolution below the diffraction limit of an optical microscope. Credits to Lucia Gardini
Single-molecule localization microscope
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- 3D tracking and super-resolution – Wide-field Single Molecule Microscope. Several laser lines are available for excitation of fluorescent probes in the visible range combined with multiple fluorescence filters to select the fluorescence emission. The same setup allows imaging of biological structures with 3D super-resolution STORM with multiple colours with about 10 nm accuracy.
- 2D Single Molecule Tracking – commercial epifluorescence microscope equipped with EMCCD camera, a dual viewer for simultaneous two-colour imaging and thermostatic system
- Volumetric 3D super-resolution: combination of PALM 3D microscopy with confined inclined illumination, it allows to achieve volumetric PALM up to 100 microns depth in transparent samples. Combination with Expansion Microscopy possible.
Ultrafast force-clamp spectroscopy
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- The ultrafast force-spectroscopy setup is primarily used in studies of mechanical properties of proteins, molecular motors, DNAs, etc. It is based on a 1064 nm dual-trap optical tweezers.
Optical tweezers and fluorescence microscopy in cells
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- This setup allows concomitant mechanical stimulation of cellular membrane with 976, or 1064 nm laser sources and wide-field fluorescence imaging.
FRET microscopy
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- Foster Resonance Energy Transfer (FRET) Microscopy is available for different FRET couples, optimised for cellular imaging.
Light-sheet microscopes: for imaging of cleared tissue and of zebrafish; for high-throughput, high-speed and high-resolution 3D imaging
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- Tissue transformation facility (CLARITY and SHIELD based)
- Biochemical lab equipped with tools and reagents for tissue clearing and staining.
- Light-sheet microscope for sub-cellular imaging of cleared murine organs.
- Two-photon light-sheet microscope for zebrafish imaging.
- Double-inverted light-sheet microscope for sub-cellular imaging of human tissue slabs (1 mm thick).
- GPU cluster for image processing
Laser-scanning microscopes for biological samples
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- two-photon microscope laser-scanning microscope for highly-scattering samples
- three-photon microscope laser-scanning microscope for very high penetration in tissues
- confocal laser-scanning microscope microscope for high resolution imaging in biological samples
- microRaman microscope for imaging based on chemical contrast
Fluorescence Lifetime & SHG Imaging
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- Multimodal non-linear, FLIM, and Raman microscope for tissue imaging and characterization
- Fluorescence lifetime imaging probe
Aperture-type Scanning Near-field Optical Microscope
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- equipped with sources and detectors in the visible and near-infrared. The microscope allows hyper-spectral imaging of different optical signals (photoluminescence, resonant scattering, reflection, transmission) with deep-subwavelength spatial resolution. The setup is also combined with a Confocal Microscope and a Dark-Field Microscope

Aperture-type Scanning Near-field Optical Microscope combined with a Confocal Microscope and a Dark-Field Microscope.Credits to Francesca Intonti.
Scattering-type scanning Near-field Optical Microscope
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- equipped with sources and detectors in the visible, provides polarization resolved nanoscale imaging of complex electromagnetic fields (amplitude & phase)
Low-temperature and time resolved confocal microscope
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- custom confocal microscope equipped with a low-vibration continuous He-flow cryostat (8-330 K) which in turn is mounted on x-y translation stages. The excitation wavelengths span the range 400 – 900 nm, while the detection is in the interval 350 – 1600 nm
Time-resolved Transient Grating Experiments and Optical Kerr Effect, based on picosecond or femtosecond laser pulses
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- green laser is the single-mode laser (2 watt at 532 nm wavelength) used to probe the impulsive grating induced in the sample by picosecond laser pulses (25 picosecond pulse duration at 1064 nm)
Time-Domain Spectroscopy with Pulses from THz to UV, based on femtosecond laser conversion, including multidimensional spectroscopy
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- converting optical femtosecond laser pulse into the THz frequency by non-linear processes in air plasma. Broad band spectrum covering frequency from tenths to tens of THz
- set-up for transient absorption spectroscopy in the NIR-VIS-UV regions
- 2D ES Spectroscopy with ultra-short pulses (<=10 fs)
- 2D IR Spectroscopy in the MIR region
- A pump-probe experimental setup utilizing two synchronized femtosecond lasers enables rapid time-scale scanning without the need for mechanical delay between the pump and probe pulses. The synchronization of the repetition rates allows for scan acquisitions to be completed within a timespan of milliseconds.
One- and Two-Photon Induced Fluorescence Spectroscopy
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- Custom-designed setup tailored for fluorescence measurements in diamond anvil cells (up to 30 GPa), utilizing picosecond visible or UV laser pulses.
Micro-Raman Spectroscopy
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- Fully automated Custom micro-Raman system capable of high-pressure measurements in diamond anvil cells (up to 50 GPa) over a broad temperature range (10 K–1000 K). The system achieves a spatial resolution of 2 microns and operates with red and green laser excitation sources.
FTIR Spectroscopy
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- Modified Bruker Vertex V80 FTIR system, adapted for high-pressure studies (up to 50 GPa) in diamond anvil cells over a temperature range of 10 K–1000 K. The setup offers an accessible spectral range spanning from the visible (Vis) to the far-infrared (FIR) region.
X-Ray Diffraction
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- Modified Bruker Vertex V80 FTIR system, adapted for high-pressure studies (up to 50 GPa) in diamond anvil cells over a temperature range of 10 K–1000 K. The setup offers an accessible spectral range spanning from the visible (Vis) to the far-infrared (FIR) region.
Liquid and solid-state samples characterization
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- Steady state spectrometers and fluorimeters, FTIR, DLS
Two-photon Direct laser writing with (NanoScribe GmbH)
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- Femtosecond laser @ 780 nm for two-photon absorption photo-polymerization
- 3D printing in mm3 volumes
- Resolution of 150 nm in the x-y plane and 300 nm in the z-direction
- Custom resins (liquid crystal and hydrogel-based formulations) with additional responsive properties
Ultracold Quantum Matter Laboratories
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- State-of-the-art and versatile experimental set-ups to produce and investigate ultracold quantum matter and for quantum simulation
- Microscope objectives for high resolution imaging and manipulation of the quantum gases
- Digital Micromirror devices for tailoring arbitrary optical potentials
Light for quantum technologies
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- High repetition rate heralded single photon generation and addition based on pulsed parametric down-conversion;
- High frequency, time-domain, homodyne detection for the tomographic reconstruction of pulsed quantum states of light;
- Advanced schemes for the manipulation and analysis of non-classical light at the single-photon level over multiple spectrotemporal modes;
- Telecom fibre components: Single-photon detectors, wide-bandwidth homodyne detectors, high-speed modulators;
- Ultra-fast electronics;
- Cryo-free cooler at 3K, with flexible optical access;
- Time-resolved and correlation measurements for the characterization of quantum emitters at the single photon level;
- Advanced schemes for the detection and the quantum control of individual electronic and nuclear spins in diamond, based on a combination of optical scanning microscopy and magnetic resonance tools;
- Femtosecond amplified lasers for diamond micro-fabrication and deterministic defect activation