A focusing optical phased array for tissue interrogation with side-lobe suppression and simplified beam steering
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| Main Authors: | , , , , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866908457285713920 |
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| author | Hosseini, Pedram Mashayekh, Alireza Tabatabaei Agrawal, Prachi Ding, Yuntian Mártir, Alvaro Moscoso Rodrigo, Rebecca Johnen, Sandra Merget, Florian Witzens, Jeremy |
| author_facet | Hosseini, Pedram Mashayekh, Alireza Tabatabaei Agrawal, Prachi Ding, Yuntian Mártir, Alvaro Moscoso Rodrigo, Rebecca Johnen, Sandra Merget, Florian Witzens, Jeremy |
| contents | We implement an integrated multi-electrode array on a silicon-nitride-based photonic integrated circuit for ex-vivo retinal characterization via optical stimulation. The interrogation beam formers, based on curved grating emitters and optical phased arrays, are designed to achieve transverse focusing with spot sizes in the 1 - 2 $μ$m range to target single cells. The experimentally realized focusing optical phased arrays show suppressed side-lobes, with approximately 11.5% of the power in each side-lobe and ~60% in the main lobe, reducing unintentional cellular excitation. Additional design refinement enables further suppression of the side-lobes to a few percent of the total power. Additionally, we demonstrate a compact design of meandered thermal phase shifters implemented across the array that allow push-pull steering in the transverse direction as well as focusing and defocusing of the beam, with a total of only four control signals. Transverse angular steering by $\pm$5.1° and axial translation of the focal spot by 204 $μ$m are demonstrated with tuning currents below 50 mA, together with longitudinal angular steering by 4.26° obtained by means of wavelength tuning in a $\pm$15 nm range centered on 525 nm. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2507_15018 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | A focusing optical phased array for tissue interrogation with side-lobe suppression and simplified beam steering Hosseini, Pedram Mashayekh, Alireza Tabatabaei Agrawal, Prachi Ding, Yuntian Mártir, Alvaro Moscoso Rodrigo, Rebecca Johnen, Sandra Merget, Florian Witzens, Jeremy Optics We implement an integrated multi-electrode array on a silicon-nitride-based photonic integrated circuit for ex-vivo retinal characterization via optical stimulation. The interrogation beam formers, based on curved grating emitters and optical phased arrays, are designed to achieve transverse focusing with spot sizes in the 1 - 2 $μ$m range to target single cells. The experimentally realized focusing optical phased arrays show suppressed side-lobes, with approximately 11.5% of the power in each side-lobe and ~60% in the main lobe, reducing unintentional cellular excitation. Additional design refinement enables further suppression of the side-lobes to a few percent of the total power. Additionally, we demonstrate a compact design of meandered thermal phase shifters implemented across the array that allow push-pull steering in the transverse direction as well as focusing and defocusing of the beam, with a total of only four control signals. Transverse angular steering by $\pm$5.1° and axial translation of the focal spot by 204 $μ$m are demonstrated with tuning currents below 50 mA, together with longitudinal angular steering by 4.26° obtained by means of wavelength tuning in a $\pm$15 nm range centered on 525 nm. |
| title | A focusing optical phased array for tissue interrogation with side-lobe suppression and simplified beam steering |
| topic | Optics |
| url | https://arxiv.org/abs/2507.15018 |