Fourier-domain optical coherence tomography utilising a seeded SU(1,1) interferometer achieves an axial resolution of approximately one micrometre. ICFO, Institut de Ciencies Fotoniques and Universitat Politecnica de Catalunya scientists reconstructed three-dimensional images from photon flux measurements centred at 810nm after probing multilayer objects with light at 1550nm. Volumetric imaging previously relied on single-photon detectors; however, seeding increases photon flux enabling use of spectrometers instead. Optical coherence tomography has been refined by employing a new technique utilising seeded interferometry which improves image clarity without requiring costly detection equipment.

The method enables detailed three-dimensional scans of layered materials through effective boosting of light signals even when amplification levels are low. Consequently, it represents an incremental advancement towards simpler and potentially less expensive volumetric imaging systems than those currently available. Scientists at ICFO, Institut de Ciencies Fotoniques and Universitat Politecnica de Catalunya advanced optical coherence tomography by utilising a technique akin to ultrasound but employing light instead of sound waves to create images beneath surfaces.

Their new method centres on seeded SU(1,1) interferometry; this involves a special arrangement of mirrors and beamsplitters that amplifies faint light signals in a controlled way, much like how a catalyst speeds up a chemical reaction. This approach allows for detailed three-dimensional scans of layered materials with an axial resolution reaching approximately one micrometre, even when the amplification, or parametric gain, is low. The team demonstrated volumetric imaging using spectrometers rather than single-photon detectors, raising questions about whether seeding offers a more effective path towards improved sensitivity compared to increasing signal strength.

Seeding enhances spectrometer performance enabling high-resolution volumetric imaging

A resolution of approximately one micrometre axially was achieved with volumetric imaging via spectrometers, previously necessitating single-photon detectors. This advance stemmed from seeding which boosted photon flux in low parametric-gain regimes; conventional methods focused solely on increasing amplification, but this novel approach bypasses limitations inherent within weak signals. The seeded SU(1,1) interferometer facilitated detailed three-dimensional scans of multilayer objects using light centred at 1550nm reconstructed through measurements taken at 810nm and represents a step towards simpler, more accessible optical coherence tomography systems.

Analysis confirms that seeding provides greater sensitivity enhancement than elevating the power of the initial signal itself, presenting an alternative pathway for improved image clarity. Volumetric imaging confirmed an axial resolution reaching approximately one micrometre when utilising a spectrometer instead of single-photon detectors typically required for such high resolutions.

Introducing additional light from a superluminiscent diode with a spectral width of 40nm increased photon flux within the system operating in a low parametric gain regime where amplification was initially around 7x 10−5. Furthermore, analysis revealed enhanced sensitivity through seeding proved more effective compared to increasing pump power up to 3.5mW; current results do not yet demonstrate performance across complex biological tissues or indicate scalability for clinical applications.

Reducing detector costs for high resolution biomedical image acquisition

The development provides a potential route towards affordable three-dimensional imaging as existing optical coherence tomography systems frequently depend on expensive single-photon detectors to capture faint light signals. ICFO researchers explicitly state their findings are limited “under the conditions considered”, raising concerns about how well this seeded approach will perform with real-world samples exhibiting varying properties, or subtle changes in experimental setup.

Despite these limitations regarding sample complexity, this demonstration of Fourier-domain optical coherence tomography (FD-OCT) using seeding remains striking; FD-OCT is a technique employing light waves to create detailed cross-sectional images within materials like biological tissue.

The team at ICFO, collaborating with Universitat Politecnica de Catalunya and The Barcelona Institute of Science and Technology, has demonstrated an innovative method for three-dimensional imaging utilising light waves. By employing a seeded SU(1,1) interferometer they enhanced photon detection even when amplification levels were low enabling volumetric scans using standard spectrometers instead. A specialised interferometer, a device combining light beams, successfully captured these images without reliance on costly single-photon detectors typically needed for faint signals.

This research demonstrates that seeding a Fourier-domain optical coherence tomography system increases the detected signal allowing detailed three-dimensional images to be reconstructed from measurements at 810nm. This approach enables volumetric imaging with readily available spectrometer technology rather than requiring expensive single-photon detectors which reduces potential costs. The researchers found this method of enhancing sensitivity through seeding was more effective than increasing parametric gain under their experimental conditions involving broadband light centred at 1550nm and spectral widths of 40nm. They note further work is required to assess performance on complex biological tissues.

👉 More information
🗞 Seeded SU(1,1) interferometry for Fourier-domain optical coherence tomography
✍️ Alejandra A. Padilla, Valentina Gacha, Daniel F. Urrego and Juan P. Torres
🧠 ArXiv: https://arxiv.org/abs/2608.18750

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