The Euler bend: paving the way for high-density integration on micron-scale semiconductor platforms

Cherchi, Matteo; Ylinen, Sami; Harjanne, Mikko; Kapulainen, Markku; Vehmas, Tapani; Aalto, Timo

doi:10.1117/12.2039912

Cited by 12 publications

(5 citation statements)

References 5 publications

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“…The answer is actually yes, as explained in details in Refs. [5], [7]. For example we have demonstrated low-loss bends with effective bending radii as small as 1.27 µm and micron-scale bends with losses below as 0.01 dB/90°, all effectively operating as single mode over very broad wavelength ranges.…”

Section: An Enabling Breakthrough: the Euler Bendmentioning

confidence: 94%

Compact low-loss delay lines on a micron-scale SOI platform

Cherchi

Harjanne

Ylinen

et al. 2014

11th International Conference on Group IV Photonics (GFP)

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Section: An Enabling Breakthrough: the Euler Bendmentioning

confidence: 94%

Compact low-loss delay lines on a micron-scale SOI platform

Cherchi

Harjanne

Ylinen

et al. 2014

11th International Conference on Group IV Photonics (GFP)

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“…Various curve geometries are available, typically s-bend trajectories are defined by concatenated circular arcs, raised sine curves or cosine curves. 28 In more recent years, euler 29 and bezier 30 curves have become common, especially in the context of complex circuit layouts. In this work, the s-bend geometry is defined by the following cosine bending formula:…”

Section: Uli Photonic Fan-in/fan-outmentioning

confidence: 99%

Improved integration density with ultra-fast laser written fiber fan-in/fan-out for broadband coupling to silicon photonics

Ross-Adams,

Withford,

Gross

2024

Optical Interconnects XXIV

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There is an evolving need for higher integration density for silicon photonic integrated circuits. Broadband operation and polarisation insensitivity are highly coveted. Despite their versatility, the commonly used grating couplers are limited by their high insertion loss, narrow bandwidth, polarisation dependence and their large physical footprint. Inverse taper edge couplers, by contrast, offer lower insertion losses, with relative wavelength and polarisation insensitivity. They are of the same dimension as silicon strip waveguides, hence, coupler spacing is constrained only by the physical size of the coupled fibre, typically amounting to a minimum pitch of 127 µm. To address this constraint, we demonstrate an ultra fast laser inscribed fan-in/fan-out (FIFO) interposer, in boro-aluminosilicate glass (Corning Eagle XG). The FIFO remaps a standard V-groove array of single-mode fibers from a pitch of 127 µm to 50 µm at the silicon interface, effectively increasing the number of ports per millimetre from 8 to 20. Denser arrangements are theoretically possible with the minimum pitch constrained only by the mode-field diameter of the waveguides. The FIFO employs a novel multi-pass waveguide morphology with a high index contrast of 1.12 × 10 −2 , allowing for a reduced mode-field diameter of 5.4 µm at 1550 nm. For coupling to a 500 × 220 nm inverse taper with a tip width of 182±1 nm, we achieve a theoretical coupling loss 3.7 dB (4.4 dB measured). Across the telecommunication band (1520 -1625 nm), we measure a flat wavelength response (0.35 dB variation) and a peak polarisation dependent loss of 0.8 dB.

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“…We show in Figure 4 an overview of the platform, including the main waveguide types and cross-sections and an example 5×10 mm 2 chip with compact arrayed waveguide gratings. The platform has a unique combination of tight bends [17][18][19] and relatively large modes, enabling dense integration with low propagation losses (≈0.1 dB/cm) and low coupling losses (≈0.5 dB to tapered fibres with 2.5 µm mode field diameter) on a very broad band. Waveguides can be coupled with equally low-loss in-plane, through facets fabricated at wafer scale (Figure 4b), or out-of-plane, through wet-etched 45° up-reflecting mirrors (Figure 4a) based on total internal reflection (TIR).…”

Section: Vtt Micron-scale Silicon Photonics Platformmentioning

confidence: 99%

Flat-top interleavers based on single MMIs

Cherchi

Sun

Kapulainen

et al. 2020

Silicon Photonics XV

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We demonstrate for the first time flat-top interleavers based on cascaded Mach-Zehnder interferometers (MZIs) which use only single multimode interferometers (MMIs) as power splitters. Our previous designs were based on 4-stage cascades of MZIs, where we used single MMIs and double MMIs to achieve 85:15 splitting ratio and 31:69 splitting ratio respectively. This time, we propose instead a greatly simplified 2-stage configuration using only single MMIs, including a standard 50:50 MMI, and two tapered MMIs to achieve 71:29 and 92:08 splitting ratios. We have designed the interleaver based on its geometrical representation on the Bloch sphere, then confirmed by efficient 2D simulations of the building blocks and of the whole structure, based on the eigenmode expansion method. We show how important is to take into account the phase relations between the outputs of all MMIs in order to make a working design. We have successfully fabricated devices with different channel spacing on our micron-scale silicon photonics platform, and measurement results confirmed their expected flat-top operation on a broad band. Using only single MMI splitters we can not only greatly outperform the bandwidth achieved by standard directional couplers, but we can also ensure much higher robustness to fabrication errors, also compared to previous demonstrations based on double MMIs. Indeed, when compared to those previous attempts, the new results prove tapered MMIs to be the most robust approach to achieve arbitrary splitting ratios.

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The Euler bend: paving the way for high-density integration on micron-scale semiconductor platforms

Cited by 12 publications

References 5 publications

Compact low-loss delay lines on a micron-scale SOI platform

Compact low-loss delay lines on a micron-scale SOI platform

Improved integration density with ultra-fast laser written fiber fan-in/fan-out for broadband coupling to silicon photonics

Flat-top interleavers based on single MMIs

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