Scaling programmable silicon photonics circuits

Bogaerts, Wim; Nagarjun, K. P.; Iseghem, Lukas Van; Chen, Xiangfeng; Deng, Hong; Zand, Iman; Liu, Yichen; Takabayashi, Alain Yuji; Sattari, Hamed; Quack, Niels; Edinger, Pierre; Jo, Gaehun; Bleiker, Simon J.; Gylfason, Kristinn B.; Niklaus, Frank; Mallik, Arun Kumar; Jezzini, Moises; Antony, Cleitus; Talli, Giuseppe; Verheyen, Peter; Beeckman, Jeroen; Khan, Umar

doi:10.1117/12.2647293

Cited by 2 publications

(2 citation statements)

References 70 publications

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“…In the domain of photonic sensor development, silicon nitride has emerged as a material of choice due to its wide transparency window and compatibility with complementary metal-oxide-semiconductor (CMOS) technology. 1,2 This research focuses on evaluating two pivotal fabrication techniques for constructing sensing windows on silicon nitride substrates: the conventional etching method that combines reactive ion etching (RIE) with wet chemical etching, and a lift-off approach that involves the deposition and subsequent removal of a top cladding layer to define the sensing waveguides. The conventional etching method is known for its precision and ability to produce highly defined features, crucial for the fabrication of complex photonic structures.…”

Section: Introductionmentioning

confidence: 99%

Comparative analysis of fabrication techniques for sensing windows on silicon nitride waveguide platforms

Hinum-Wagner,

Hörmann,

Feigl

et al. 2024

Integrated Photonics Platforms III

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This study provides an in-depth evaluation of two fundamental techniques for fabricating sensing windows on silicon nitride platforms: a traditional etching strategy using reactive ion etching (RIE) combined with wet etching, and a lift-off-based process in which the top cladding material is deposited onto a suitable resist which is subsequently stripped of the distinct sensing waveguides. The analysis, based on a side-by-side comparison, meticulously examines the effectiveness of these methods. Key evaluation metrics include propagation and bending loss in the sensing windows, process robustness, and uniformity of critical dimensions and heights across the wafer. This will provide a comprehensive understanding of the strengths, weaknesses, and potential application limitations of each technique. An integral part of the study is the careful revision of the waveguide material stack to address specific challenges and applications. This precise tuning and adaptation of the material stack serve as a proxy for the demands likely to be encountered in real-world applications. The conservative etching technique has the advantage that it can be easily combined with subsequent facet etching processes for edge coupling approaches. Conversely, the lift-off resist based approach, despite its relative complexity and sensitivity to high-temperature deposition on the resist, reduces the negative impact of the process on surface roughness and sidewall angles. The knowledge gained from this research provides valuable guidance in the selection of appropriate fabrication techniques for specific silicon nitride sensor applications to increase the robustness of the processing steps for potential mass production stability.

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Section: Introductionmentioning

confidence: 99%

Comparative analysis of fabrication techniques for sensing windows on silicon nitride waveguide platforms

Hinum-Wagner,

Hörmann,

Feigl

et al. 2024

Integrated Photonics Platforms III

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“…Integrated photonics, the domain encompassing the manipulation and propagation of light on micro and nano scales, has progressively emerged as a critical technology across various fields such as high-speed telecommunications, high-performance computing, and intricate sensing applications. 1,2 Despite the transformative role of this technology, the operational proficiency of these photonics systems is continually challenged by optical losses occurring within their waveguide structures. Two predominant sources contribute to these losses: surfaceroughness-induced scattering and absorption losses.…”

Section: Introductionmentioning

confidence: 99%

Ab-initio modeling of bend-losses in silicon nitride waveguides from visible to near-infrared

Hinum-Wagner,

Hörmann,

Sattelkow

et al. 2023

Optical Modeling and Performance Predictions XIII

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Integrated photonics features applications in high-speed telecommunication, computing, and sensing. These devices are ultimately limited by the optical loss occurring in the waveguide structures. One of its primary sources is surface-roughness-induced scattering and bend-losses. Surface roughness is unavoidably introduced during deposition, mainly during etching and lithographic steps. In photonic integrated circuits, tight bends enable a compact footprint yet increase the mode mismatch loss , radiation loss and scattering loss. Previously, the bend losses were estimated from a parametric model. However, it lacks flexibility w.r.t. the waveguide platform. We apply a recently developed model of the surface-roughness-induced scattering in guided-mode systems to substantiate the dependence of the scattering loss on the bend-radius for waveguides based on a silicon nitride platform. The model incorporates the surface roughness via its autocorrelation. Further, it inherently considers the overlap of the modes with the roughness. As waveguide material, we used both plasma-enhanced CVD silicon nitride as a low-temperature, back-end-compatible process, and low-pressure CVD silicon nitride, as a high-temperature frontend process. As bottom and top cladding, we deposited high-density plasma (HDP) and sputtered silicon oxide, respectively. The latter offers flexibility to adapt the platform for sensing purposes. We evaluate different waveguide widths, bend radii, and wavelengths in the visible and near-infrared ranges. We set the observed propagation losses into context with estimated absorption, scattering, and mode-overlap loss sources and point to their shifting importance at the measured wavelengths. We believe that this model allows to increase our knowledge about the various aspects of loss in guided mode systems and predict the propagation loss based on foregoing absorption and roughness measurements.

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Scaling programmable silicon photonics circuits

Cited by 2 publications

References 70 publications

Comparative analysis of fabrication techniques for sensing windows on silicon nitride waveguide platforms

Comparative analysis of fabrication techniques for sensing windows on silicon nitride waveguide platforms

Ab-initio modeling of bend-losses in silicon nitride waveguides from visible to near-infrared

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