Focusing optical phased array for tissue interrogation with improved side-lobe suppression and simplified beam
Pedram Hosseini1, Alireza Tabatabaei Mashayekh1, Prachi Agrawal1
1Institute of Integrated Photonics, RWTH Aachen University, Campus Boulevard 73, 52074 Aachen, Germany.
Biomedical Optics Express
|January 14, 2026
Summary
This study presents a silicon nitride photonic integrated circuit for ex-vivo retinal cell characterization. It uses optical phased arrays for precise optical stimulation, enabling targeted single-cell analysis.
Area of Science:
- Photonics
- Neuroscience
- Biomedical Engineering
Background:
- Ex-vivo retinal characterization requires precise optical stimulation methods.
- Existing techniques may lack the resolution or control for single-cell targeting.
Purpose of the Study:
- To develop an integrated photonic circuit for high-resolution ex-vivo retinal analysis.
- To achieve precise optical stimulation of individual retinal cells using optical phased arrays.
Main Methods:
- Implementation of a silicon nitride photonic integrated circuit with a multi-electrode array.
- Design and experimental realization of curved grating emitters and optical phased arrays for beam forming.
- Utilizing meandered thermal phase shifters for beam steering and focusing control.
Main Results:
- Achieved transverse focusing with 1-2 µm spot sizes for single-cell targeting.
- Demonstrated optical phased arrays with suppressed side-lobes (few percent power).
- Showcased beam steering (±5.1° transverse, 4.26° longitudinal) and focal spot translation (204 µm axial) with low currents and wavelength tuning.
Conclusions:
- The developed photonic integrated circuit enables precise optical stimulation for ex-vivo retinal characterization.
- The system offers significant improvements in targeting accuracy and reduced off-target cellular excitation.
- This technology holds potential for advancing retinal research and diagnostics.
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