Vertically Curved Si Waveguide Coupler with Low Loss and Flat Wavelength Window

Yoshida, Tomoya; Omoda, Emiko; Atsumi, N; Nishi, Takanori; Tajima, Syougo; Miura, N.; Mori, Masahiko; Sakakibara, Youichi

doi:10.1109/jlt.2015.2506732

Cited by 24 publications

(15 citation statements)

References 29 publications

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“…6) includes the ion implantation loss. Previously, we reported that the annealing treatment reduces the ion implantation loss caused by the IIB process [10]. According to our estimation, we expect a loss reduction of about 0.5 dB by annealing.…”

Section: Measurementmentioning

confidence: 51%

“…Compared with GCs, the elephant coupler has an inverse-tapered SSC at the top, with a lens-shaped SiO 2 dome, and has advantages of low coupling loss, broadband coupling, and flexibility in beam direction. [8]- [10] Recently, we have reported on a coupler with a beam-spot size of 5 µm for coupling with high numerical aperture single-mode fibers (HNA-SMFs). The device fabricated using electron-beam (EB) lithography demonstrated broadband coupling operations with coupling losses of 2.4 dB at a wavelength of 1550 nm and a 0.5-dB spectrum bandwidth of more than 220 nm with TE-polarization light.…”

Section: Introductionmentioning

confidence: 99%

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Polarization-Insensitive Vertically Curved Si Surface Optical Coupler Bent by Ion Implantation

Yoshida

Akizuki

Omoda

et al. 2020

IEEE Photon. Technol. Lett.

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For input coupling from single-mode optical fibers to photoreceivers made with silicon photonics integrated circuits (Si-PICs), we constructed a polarization-insensitive optical surface coupler with a vertically curved silicon waveguide. The polarization insensitivity was attained by the equalization of the radiative transmission losses of TE and TM polarizations in the vertically curved waveguide (VCW) structure while keeping the straight structure of the spot-size converter (SSC) connected above the curved structure. Numerical simulations revealed that the radius of curvature of 6 µm or larger nearly enabled the equalization, and thus we developed a bending technology using ion implantation to realize simultaneously a VCW radius of curvature of 6 µm and a straight SSC of length 7 µm by varying the implantation angles. The bent silicon core was subsequently coated with SiO 2 by plasma-enhanced chemical vapor deposition to function as a collimation lens. The coupling properties of the fabricated coupler and the single-mode fiber with a mode-field diameter of 5 µm exhibited a polarization dependence loss of less than 0.25 dB, a 1-dB bandwidth of 180 nm, and coupling losses of about 1.6 dB at 1550 nm wavelength. A sharp inversely tapered Si waveguide that affects these characteristics significantly can be formed by applying ArF-immersion lithography on the 45-nm-node and hence fabrication is compatible with mass production processes.

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Section: Measurementmentioning

confidence: 51%

Section: Introductionmentioning

confidence: 99%

Polarization-Insensitive Vertically Curved Si Surface Optical Coupler Bent by Ion Implantation

Yoshida

Akizuki

Omoda

et al. 2020

IEEE Photon. Technol. Lett.

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“…The main drawback of this technique is due to the additional waveguide propagation loss introduced by the increased concentration of lattice defects. The propagation loss increases from 0.05 dB/μm at 2 × 10 15 ions∕cm 2 to 0.1 dB/μm at 1.7 × 10 16 ions∕cm 2 , showing saturation for higher levels of ions doses [42].…”

Section: Vertical End-fire Couplersmentioning

confidence: 95%

“…One of the main limitations for edge coupling solutions is related to their incompatibility with wafer-level testing of the photonic circuits and devices. A possible solution to this problem has been provided by Yoshida et al [40][41][42][43] who proposed a novel vertical end-fire coupler scheme, also known as an "elephant" coupler. This coupler used a vertically swept SOI strip waveguide, realized by means of an ion implantation process to achieve a radius of curvature in the order of a few μm.…”

Section: Vertical End-fire Couplersmentioning

confidence: 99%

Coupling strategies for silicon photonics integrated chips [Invited]

Marchetti¹,

Lacava²,

Carroll³

et al. 2019

Photon. Res.

436

206

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Over the last 20 years, silicon photonics has revolutionized the field of integrated optics, providing a novel and powerful platform to build mass-producible optical circuits. One of the most attractive aspects of silicon photonics is its ability to provide extremely small optical components, whose typical dimensions are an order of magnitude smaller than those of optical fiber devices. This dimension difference makes the design of fiberto-chip interfaces challenging and, over the years, has stimulated considerable technical and research efforts in the field. Fiber-to-silicon photonic chip interfaces can be broadly divided into two principle categories: in-plane and out-of-plane couplers. Devices falling into the first category typically offer relatively high coupling efficiency, broad coupling bandwidth (in wavelength), and low polarization dependence but require relatively complex fabrication and assembly procedures that are not directly compatible with wafer-scale testing. Conversely, out-of-plane coupling devices offer lower efficiency, narrower bandwidth, and are usually polarization dependent. However, they are often more compatible with high-volume fabrication and packaging processes and allow for on-wafer access to any part of the optical circuit. In this paper, we review the current state-of-the-art of optical couplers for photonic integrated circuits, aiming to give to the reader a comprehensive and broad view of the field, identifying advantages and disadvantages of each solution. As fiber-to-chip couplers are inherently related to packaging technologies and the co-design of optical packages has become essential, we also review the main solutions currently used to package and assemble optical fibers with silicon-photonic integrated circuits.

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“…However, these gratings are designed to present the direction of the maximum radiation in an angle greater than 20°. Non-vertical radiation increases the packaging complexity and cost dramatically in applications such as fiber-to-chip coupling [21]. Unfortunately, if the grating is designed to radiate vertically, the antenna efficiency drops sensibly since a great amount of intensity is reflected back toward the feeding waveguide.…”

Section: Introductionmentioning

confidence: 99%

Design of a compact CMOS-compatible photonic antenna by topological optimization

et al. 2018

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Photonic antennas are critical in applications such as spectroscopy, photovoltaics, optical communications, holography, and sensors. In most of those applications, metallic antennas have been employed due to their reduced sizes. Nevertheless, compact metallic antennas suffer from high dissipative loss, wavelength-dependent radiation pattern, and they are difficult to integrate with CMOS technology. All-dielectric antennas have been proposed to overcome those disadvantages because, in contrast to metallic ones, they are CMOS-compatible, easier to integrate with typical silicon waveguides, and they generally present a broader wavelength range of operation. These advantages are achieved, however, at the expense of larger footprints that prevent dense integration and their use in massive phased arrays. In order to overcome this drawback, we employ topological optimization to design an all-dielectric compact antenna with vertical emission over a broad wavelength range. The fabricated device has a footprint of 1.78 µm × 1.78 µm and shows a shift in the direction of its main radiation lobe of only 4° over wavelengths ranging from 1470 nm to 1550 nm and a coupling efficiency bandwidth broader than 150 nm.

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Vertically Curved Si Waveguide Coupler with Low Loss and Flat Wavelength Window

Cited by 24 publications

References 29 publications

Polarization-Insensitive Vertically Curved Si Surface Optical Coupler Bent by Ion Implantation

Polarization-Insensitive Vertically Curved Si Surface Optical Coupler Bent by Ion Implantation

Coupling strategies for silicon photonics integrated chips [Invited]

Design of a compact CMOS-compatible photonic antenna by topological optimization

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