Design of compact surface optical coupler based on vertically curved silicon waveguide for high-numerical-aperture single-mode optical fiber

Atsumi, N; Yoshida, Tomoya; Omoda, Emiko; Sakakibara, Youichi

doi:10.7567/jjap.56.090307

Cited by 15 publications

(14 citation statements)

References 21 publications

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“…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. [11]- [13] However, in this demonstration, the minimum coupling loss of the TM polarization was 1 dB larger than that of the TE polarization. Reducing the PDL as much as possible remains an important problem.…”

Section: Introductionmentioning

confidence: 55%

“…The elephant coupler is composed of two sections: a VCW and an SSC [ Fig. 1(a)] [11]. The VCW section bends light through a right angle towards the surface of a chip, and the SSC enlarges the optical profile of the Si waveguide to match that of the optical fiber.…”

Section: Device Designmentioning

confidence: 99%

“…1(b)]. The waveguide width and height are 430 and 220 nm, respectively, and the SiO 2 thickness surrounding the Si waveguide was set at 2.4, 2.7, and 3.0 µm as determined in previous work [11]. With a larger bending radius, the bending losses for both polarization modes diminished.…”

Section: Device Designmentioning

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: Introductionmentioning

confidence: 55%

Section: Device Designmentioning

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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“…Recently, the same authors also demonstrated the possibility to obtain light coupling between silicon vertical couplers and high numerical aperture fibers (5 μm MFD) [44,45]. Unlike their previous works, this time the Si nano-tapers were designed to show an exponential tapering profile, with the waveguide width decreasing from 430 to 50 nm over a 6 μm length, while the 90°waveguide bending was obtained by means of argon ion (Ar ) implantation (7 × 10 15 ions∕cm 2 ).…”

Section: Vertical End-fire Couplersmentioning

confidence: 99%

Coupling strategies for silicon photonics integrated chips [Invited]

Marchetti¹,

Lacava²,

Carroll³

et al. 2019

Photon. Res.

398

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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“…So far, a variety of effective coupling approaches have been demonstrated, [5] including end-fire coupling, [6][7][8][9][10][11] grating coupling, [12][13][14][15][16][17][18] and fiber-taper-assisted adiabatic coupling. [19][20][21][22][23][24] While they have been successfully applied with high efficiency and broad bandwidth, [8,24] high flexibility and large alignment tolerance remain challenging. To overcome these limitations, recently, photonic wire bonding based on adiabatic coupling method is proposed.…”

Section: Introductionmentioning

confidence: 99%

Efficient Fiber‐to‐Chip Interface via an Intermediated CdS Nanowire

Jin

Yang

Huang

et al. 2023

Laser & Photonics Reviews

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An efficient fiber-to-chip interface via an intermediated CdS nanowire is demonstrated. The fiber mode is firstly squeezed through a fiber taper drawn at the end of a single-mode fiber, then evanescently coupled into an intermediated CdS nanowire with a longitudinally tapering profile, and finally coupled into an on-chip silicon waveguide (SiW) via a waveguide taper fabricated on it. Since the fiber-nanowire-SiW cascade structure is designed to match effective indices in each coupling area, such a fiber-to-chip interface ensures a bidirectional coupling efficiency up to 90% and a 3-dB bandwidth over 100 nm in experiments. The difference of coupling efficiencies between the TM or TE modes is less than 0.5 dB in the spectral range of 1545-1635 nm. The footprint of the on-chip coupling structure is about 10 µm in size. The results may provide a compact, efficient, and versatile fiber-to-chip interface in applications including optical interconnects, coherent communication, and quantum optical circuitry.

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Design of compact surface optical coupler based on vertically curved silicon waveguide for high-numerical-aperture single-mode optical fiber

Cited by 15 publications

References 21 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]

Efficient Fiber‐to‐Chip Interface via an Intermediated CdS Nanowire

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