Highly Integrated Versatile Laser Source enabling two-photon excitation in digital diagnostics and biomedical research

Project Information

HILIGHT

Grant agreement ID: 101135034

DOI

10.3030/101135034

EC signature date 15 November 2023

Start date 1 December 2023

End date 30 November 2027

Funded under

• Digital, Industry and Space

Total cost

No data

EU contribution

€ 3 185 792,64

Coordinated by

III-V LAB
France

Periodic Reporting for period 1 - HILIGHT (Highly Integrated Versatile Laser Source enabling two-photon excitation in digital diagnostics and biomedical research)

Reporting period: 2023-12-01 to 2025-05-31

Summary of the context and overall objectives of the project

As a key enabling technology, photonics will play a central role in transforming sectors such as healthcare and biomedical research. HILIGHT focuses on the development and demonstration of an innovative two-photon excitation fluorescence lifetime imaging microscopy (2ph-FLIM) platform that enables unprecedented image acquisition rates. The project aims to deliver versatile, compact, and cost-effective laser and detection technologies capable of integration into the existing confocal microscopy system developped by Vivascope.
At the core of the project is the development of a laser, developped by III-V Lab and CSEM, capable of generating customizable pulse bursts at high repetition rates (3–6 GHz). This laser source will support 2ph-FLIM imaging at megapixel-per-second rates and is designed for acrydin fluorescent dye. Its performance in terms of pulse energy and peak power is comparable to the state of the art, but with significant improvements in size, energy efficiency, and manufacturing cost. Combined with a custom-designed digital Silicon Photomultiplier (dSiPM) implemented in CMOS technology, this laser will enable high-speed, high-resolution imaging while overcoming existing limitations in data acquisition and processing bandwidth. The detector, developed by FBK, employs a time-gated photon counting strategy that significantly reduces computational complexity, enabling high signal-to-noise ratio (SNR) measurements and efficient lifetime reconstruction.
HILIGHT’s technologies will be validated in two distinct use cases by Vivascope and Brunel University. The first focuses on digital histopathology, where the project seeks to replace traditional staining techniques with near-instantaneous optical biopsy capabilities. By integrating the HILIGHT system into a VivaScope platform, the project will enable rapid intraoperative diagnostics and enhanced pathology workflows. The second use case explores applications in biomedical research, particularly in the areas of single-cell biochemical phenotyping and optogenetics using three-dimensional culture systems. The project will demonstrate how HILIGHT’s ultrafast laser source can be used for confined photoactivation within tissue and how its detection system can support FLIM-based biochemical sensing at photon count rates far exceeding those of current technologies.
Through these innovations, the HILIGHT project aims to overcome the technical and economic barriers that have limited the broader adoption of two-photon microscopy. It will enable a new generation of medical and research imaging tools that are faster, more accurate, and more accessible. By targeting both clinical and research applications, HILIGHT not only addresses current limitations in biomedical imaging but also opens up new market opportunities across academic, clinical, and industrial settings.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

A review of the project concept and a preliminary design for using the HILIGHT laser source in two target applications has been completed. The state-of-the-art survey on light sources and detectors confirms our chosen strategy aligns with the project objectives. The synchronization approach for the laser, detector, and microscope has been successfully designed. An electronic driver was carefully selected to control the modulation of the HILIGHT source, meeting all project requirements.
Extensive measurements on lasers from previous projects enabled the development of a robust model for the stable mode-locked (ML) operation of the HILIGHT source. To fulfil all the requirements, the source designed is a multi-section tapered laser, and a high number of variations was simulated and designed. Three epitaxial laser structures were modelled and realized: three wafers of each structure are now ready for processing. Mask design is completed, and further processing steps will proceed over the next two months. A dedicated AlN submount for the HILIGHT source was designed to fit the butterfly module packaging and the selected electronic driver.
In parallel, a monolithic CMOS photon detector was designed to operate synchronously with the pulsed laser developed in WP2. Timing signal distribution electronics and a model for the driving and distribution network were developed. Based on WP1 analysis, a 10k-cell, single-point detector architecture was chosen, featuring SPAD cells with four 1-bit time-gated counters each. These counters operate over a ~40 ns observation window and are read out using a pipelined summation system enabling acquisition rates above 10 Msps. A preliminary block diagram for the HILIGHT microscope’s data acquisition electronics was defined, alongside the design of a new hardware platform.
To prepare for two-photon FLIM analysis at BUL, a microscope system was rebuilt and upgraded as the main testbed for integrating the HILIGHT laser and detector. The platform now includes advanced FLIM-capable detectors and timing electronics. Preparatory work such as mounting on a new optical breadboard and designing beam-shaping optics for the SPAD sensor is completed.
Simulation tools were developed to optimize the HILIGHT FLIM system, focusing on photon efficiency and performance trade-offs. A “Digital Twin” based on a Monte Carlo simulation models photon detection, supported by ongoing refinement of numerical methods. Analysis of burst width, gate number, and timing effects confirmed that flexible gate positioning and excitation timing can compensate for efficiency losses. These findings validate key design decisions and will guide further development of the HILIGHT laser and sensor.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The HILIGHT project is expected to deliver a breakthrough in biomedical imaging through the development of an ultrafast, compact, and cost-effective two-photon fluorescence lifetime imaging microscopy (2ph-FLIM) system. By combining a novel monolithic pulse burst laser source with a high-speed, low-noise digital detector, HILIGHT will enable real-time, high-resolution imaging suitable for both clinical and research environments. The main expected results include the successful integration of these technologies into the VivaScope confocal microscope platform, demonstrating unparalleled imaging speed (8 Mpx/s), enhanced depth penetration, and high SNR in digital histopathology and biomedical assays. These advances will allow for near-instantaneous tissue diagnostics, drastically reducing the time required for cancer detection and surgical decision-making.
The potential impact of HILIGHT spans several domains. Scientifically, it will open new frontiers in digital histology and cell-level biochemical phenotyping, enabling better understanding and monitoring of disease mechanisms. Economically, it promises to reduce healthcare costs by shortening diagnostic cycles, improving treatment precision, and minimizing unnecessary interventions. Socially, it will contribute to improved patient outcomes and well-being by reducing diagnostic delays and psychological stress. Moreover, the project strengthens European technological sovereignty by developing and industrializing advanced semiconductor photonics within the EU, addressing strategic priorities in healthcare innovation, digital transformation, and global competitiveness.