Low-loss and low wavelength-dependence vertical interlayer transition for 3D silicon photonics

Takei, Ryohei; Maegami, Yuriko; Omoda, Emiko; Sakakibara, Youichi; Mori, Masahiko; Kamei, Toshihiro

doi:10.1364/oe.23.018602

Cited by 24 publications

(15 citation statements)

References 19 publications

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“…Several reports describe the interlayer connections between different material waveguides [10], [11], [20], [21]. However, an in-plane connection has not yet been reported.…”

Section: In-plane-type Couplermentioning

confidence: 99%

“…Two types of couplers have been reported as devices that can transmit light from layer to layer. One is a grating coupler, and the other is a directional coupler [11], [17], [18], [20], [21]. However, these couplers have trade-offs between the complexity of the device or the interlayer thickness.…”

Section: A Device Designmentioning

confidence: 99%

“…Reference [20] demonstrated a directional-type coupler with an interlayer thickness of 200 nm; however, this coupler caused interlayer crosstalk that could not be ignored. Another report describes a 600-nm interlayer and second-core concept [21], but then, the process flow becomes complicated. From the preceding discussion, a simple grating coupler structure using only Si and SiO2 for µm-range transmissions may be attractive.…”

Section: A Device Designmentioning

confidence: 99%

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Crystalline/Amorphous Si Integrated Optical Couplers for 2D/3D Interconnection

Itoh

Kuno

Hayashi

et al. 2016

IEEE J. Select. Topics Quantum Electron.

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The in-plane and interlayer waveguide-type couplers between crystalline Si and amorphous-Si:H wire waveguides, for 2D/3D hybrid-material integration are presented in this paper. The in-plane-type coupler achieves stable coupling between two waveguides by using tapers located at the tips of the waveguides. The interlayer-type coupler can connect two waveguides, despite an interlayer distance of 1 μm, with a simple process flow, by introducing a trident structure. An experiment was conducted in which the in-plane and interlayer-type couplers realized low coupling losses (coupling efficiencies) of 0.16 dB (96%) and 0.49 dB (89%) per coupler, respectively. Index Terms-a-Si:H waveguide, multilayer, nonlinearity, trident I. INTRODUCTION N optical interconnection is regarded as an effective technique that can realize larger-capacity and higher-speed transmissions, when compared to conventional electrical wiring. In order to realize a large-capacity optical interconnection, silicon photonics is an essential component technology; the core materials are crystalline silicon (c-Si) and silicon dioxide. Silicon photonics is compatible with CMOS fabrication processes, and its high refractive-index contrast structures allow for a small footprint [1]. So far, a number of c-Si based devices such as low-loss wire waveguides, passive devices [2], and active devices including modulators exist [3], [4]. However, c-Si does not meet the requirements for some complex optical devices and systems because of its material properties. Unfortunately, c-Si has a poor luminescence property [5] and high optical nonlinearity [6]. In addition, it cannot be stacked as a multilayer owing to the high M anuscript received Xxx x, xxxx; revised Xxx xx, xxxx and Xxx xx, xxxx; accepted Xxx xx, xxxx. Date of publication Xxx xx, xxxx; date of current version Xxx x, xxxx.

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“…Several reports describe the interlayer connections between different material waveguides [10], [11], [20], [21]. However, an in-plane connection has not yet been reported.…”

Section: In-plane-type Couplermentioning

confidence: 99%

Section: A Device Designmentioning

confidence: 99%

Section: A Device Designmentioning

confidence: 99%

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Crystalline/Amorphous Si Integrated Optical Couplers for 2D/3D Interconnection

Itoh

Kuno

Hayashi

et al. 2016

IEEE J. Select. Topics Quantum Electron.

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“…The optical connection of vertically stacked optical circuit layers dramatically enhances the architecture flexibility of a circuit. Figure 8 shows our concept of a VIT device [25]. The lower Si waveguide is optically coupled with the upper a-Si:H waveguide through the silicon oxynitride (SiON) secondary core (SC).…”

Section: Structure Of the Vit Devicementioning

confidence: 99%

Amorphous Silicon Photonics

Takei¹

2016

Crystalline and Non-Crystalline Solids

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This chapter introduces our research on amorphous silicon photonics. By exploring our high-quality silicon thin-film technology, we have demonstrated hydrogenated amorphous silicon (a-Si:H) waveguides with ultra-low-loss, vertical interlayer transition (VIT) devices for cross coupling between vertically stacked optical circuits. These device technologies are promising for three-dimensional photonic integrated circuits integrated in microelectronics chips. A record low loss of 0.6 dB cm −1 was achieved for a submicron-scale single-mode waveguide, and the VIT devices allow lowloss, broadband, and polarization-insensitive operation.

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“…Our calculation shows the interlayer thickness of cladding material (usually SiO 2 ) between layers should be more than 1 µm to suppress the crosstalk to less than −30 dB as shown in Fig. 2 [8] To achieve signal coupling with a relatively thick interlayer thickness, several proposals were demonstrated [9], [10]. We proposed two types of couplers.…”

Section: Introductionmentioning

confidence: 96%

Si-Photonics-Based Layer-to-Layer Coupler Toward 3D Optical Interconnection

Nishiyama

Kang

Kuno

et al. 2018

IEICE Trans. Electron.

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SUMMARY To realize three-dimensional (3D) optical interconnection on large-scale integration (LSI) circuits, layer-to-layer couplers based on Si-photonics platform were reviewed. In terms of optical cross talk, more than 1 µm layer distance is required for 3D interconnection. To meet this requirement for the layer-to-layer optical coupler, we proposed two types of couplers: a pair of grating couplers with metal mirrors for multi-layer distance coupling and taper-type directional couplers for neighboring layer distance coupling. Both structures produced a high coupling efficiency with relatively compact (∼100 µm) device sizes with a complementary metal oxide semiconductor (CMOS) compatible fabrication process.

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Low-loss and low wavelength-dependence vertical interlayer transition for 3D silicon photonics

Cited by 24 publications

References 19 publications

Crystalline/Amorphous Si Integrated Optical Couplers for 2D/3D Interconnection

Crystalline/Amorphous Si Integrated Optical Couplers for 2D/3D Interconnection

Amorphous Silicon Photonics

Si-Photonics-Based Layer-to-Layer Coupler Toward 3D Optical Interconnection

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