Monolithically Integrated, CMOS-Compatible SiN Photonics for Sensing Applications

In this work, we present a significant step toward in vivo ophthalmic optical coherence tomography and angiography on a photonic integrated chip. The diffraction gratings used in spectral-domain optical coherence tomography can be replaced by photonic integrated circuits comprising an arrayed waveguide grating. Two arrayed waveguide grating designs with 256 channels were tested, which enabled the first chip-based optical coherence tomography and angiography in vivo three-dimensional human retinal measurements. Design 1 supports a bandwidth of 22 nm, with which a sensitivity of up to 91 dB (830 µW) and an axial resolution of 10.7 µm was measured. Design 2 supports a bandwidth of 48 nm, with which a sensitivity of 90 dB (480 µW) and an axial resolution of 6.5 µm was measured. The silicon nitride-based integrated optical waveguides were fabricated with a fully CMOS-compatible process, which allows their monolithic co-integration on top of an optoelectronic silicon chip. As a benchmark for chip-based optical coherence tomography, tomograms generated by a commercially available clinical spectral-domain optical coherence tomography system were compared to those acquired with on-chip gratings. The similarities in the tomograms demonstrate the significant clinical potential for further integration of optical coherence tomography on a chip system.

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“…A description of what such a CMOS-compatible photonic process flow could look like can be found in ref. 42 . The inset of Fig.…”

Section: Arrayed Waveguide Gratingmentioning

confidence: 99%

Toward optical coherence tomography on a chip: in vivo three-dimensional human retinal imaging using photonic integrated circuit-based arrayed waveguide gratings

et al. 2021

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“…The SiN waveguides were fabricated at ams AG in a CMOS-compatible process using lowtemperature plasma-enhanced chemical vapor deposition (PECVD), deep UV photolithography, and reactive ion etching, which allows monolithic co-integration in the back-end-of-line (BEOL) with silicon photodiodes and read-out electronics [18]. The upper and lower SiO 2 cladding thickness was set to 3 µm.…”

Section: Retinal Oct Imaging At 840 Nmmentioning

confidence: 99%

Multi-channel swept source optical coherence tomography concept based on photonic integrated circuits

Nevlacsil¹,

Müellner²,

Maese-Novo³

et al. 2020

Opt. Express

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In this paper, we present a novel concept for a multi-channel swept source optical coherence tomography (OCT) system based on photonic integrated circuits (PICs). At the core of this concept is a low-loss polarization dependent path routing approach allowing for lower excess loss compared to previously shown PIC-based OCT systems, facilitating a parallelization of measurement units. As a proof of concept for the low-loss path routing, a silicon nitride PIC-based single-channel swept source OCT system operating at 840 nm was implemented and used to acquire in-vivo tomograms of a human retina. The fabrication of the PIC was done via CMOS-compatible plasma-enhanced chemical vapor deposition to allow future monolithic co-integration with photodiodes and read-out electronics. A performance analysis using results of the implemented photonic building blocks shows a potential tenfold increase of the acquisition speed for a multi-channel system compared to an ideal lossless single-channel system with the same signal-to-noise ratio.

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“…The different crossing configurations were then fabricated by ams AG on their SiN photonic platform [53]. The measurements of the fabricated crossings were performed with cleaved polarization maintaining fibers coupled to the device under test via end facet coupling.…”

Section: Measurement and Simulationsmentioning

confidence: 99%

Broadband low loss and ultra-low crosstalk waveguide crossings based on a multimode interferometer for 840 nm operation

Nevlacsil¹,

Müellner²,

Sagmeister³

et al. 2020

OSA Continuum

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Broadband low loss and ultra-low crosstalk waveguide crossings are a crucial component for photonic integrated circuits to allow a higher integration density of functional components and an increased flexibility in the layout. We report the design of optimized silicon nitride waveguide crossings based on multimode interferometer structures for intersecting light paths of TE/TE-like, TM/TM-like and TE/TM-like polarized light in the near infrared wavelength region of 790 nm to 890 nm. The crossing design for diverse polarization modes facilitates dual polarization operation on a single chip. For all configurations the loss of a single crossing was measured to be~0.05 dB at 840 nm. Within the 100 nm bandwidth losses stayed below 0.16 dB. The crosstalk was estimated to be on the order of −60 dB by means of 3D finite difference time domain simulations.

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Monolithically Integrated, CMOS-Compatible SiN Photonics for Sensing Applications

Cited by 12 publications

References 3 publications

Toward optical coherence tomography on a chip: in vivo three-dimensional human retinal imaging using photonic integrated circuit-based arrayed waveguide gratings

Toward optical coherence tomography on a chip: in vivo three-dimensional human retinal imaging using photonic integrated circuit-based arrayed waveguide gratings

Multi-channel swept source optical coherence tomography concept based on photonic integrated circuits

Broadband low loss and ultra-low crosstalk waveguide crossings based on a multimode interferometer for 840 nm operation

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