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2326 KiB

Open AccessArticle

Low-Loss Micro-Resonator Filters Fabricated in Silicon by CMOS-Compatible Lithographic Techniques: Design and Characterization

by Riccardo Marchetti, Valerio Vitali, Cosimo Lacava, Ilaria Cristiani, Guido Giuliani, Viviane Muffato, Maryse Fournier, Silvio Abrate, Roberto Gaudino, Enrico Temporiti, Lee Carroll and Paolo Minzioni

Appl. Sci. 2017, 7(2), 174; https://doi.org/10.3390/app7020174 - 11 Feb 2017

Cited by 21 | Viewed by 5204

Abstract

Optical resonators are fundamental building-blocks for the development of Si-photonics-integrated circuits, as tunable on-chip optical filters. In addition to the specific spectral shape, which may vary according to a particular application, extremely low losses from these devices are a crucial requirement. In the [...] Read more.

Optical resonators are fundamental building-blocks for the development of Si-photonics-integrated circuits, as tunable on-chip optical filters. In addition to the specific spectral shape, which may vary according to a particular application, extremely low losses from these devices are a crucial requirement. In the current state-of-the-art devices, most low-loss filters have only been demonstrated by exploiting ad hoc lithographic and etching techniques, which are not compatible with the standard CMOS (complementary metal-oxide semiconductor) process-flow available at Si-photonic foundries. In this paper, we describe the design and optimization of optical micro-resonators, based on Si-waveguides with a height lower than the standard ones (i.e., less than 220 nm), prepared on SOI (silicon on insulator) platform, which allow the realization of high-performance optical filters with an insertion loss lower than 1 dB, using only previously validated lithographic etch-depths. Full article

(This article belongs to the Special Issue Silicon Photonics Components and Applications)

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3301 KiB

Open AccessArticle

Luminescent Properties of Silicon Nanocrystals:Spin on Glass Hybrid Materials

by Marco Antonio Vásquez-Agustín, Orlando Cortazar-Martínez, Alfredo Abelardo González-Fernández, José Alberto Andraca-Adame, Alfredo Morales-Sánchez and Mariano Aceves-Mijares

Appl. Sci. 2017, 7(1), 72; https://doi.org/10.3390/app7010072 - 13 Jan 2017

Cited by 4 | Viewed by 5759

Abstract

The photoluminescence characteristics of films consisting of Si nanocrystals either coated with or embedded into Spin on Glass (SOG) were studied. Si nanocrystals showing red or blue luminescence when suspended in alcohol solution were obtained from porous silicon films. These were then either [...] Read more.

The photoluminescence characteristics of films consisting of Si nanocrystals either coated with or embedded into Spin on Glass (SOG) were studied. Si nanocrystals showing red or blue luminescence when suspended in alcohol solution were obtained from porous silicon films. These were then either deposited in Si substrates and coated with SOG, or mixed in an SOG solution that was later spun on Si substrates. Both types of films were thermally annealed at 1100 °C for three hours in N₂ atmosphere. Transmission electron microscopy measurements showed a mean diameter of 2.5 nm for the Si nanocrystals, as well as the presence of polycrystalline Si nanoagglomerates. These results were confirmed by X-ray diffraction studies, which revealed the (111), (220) and (311) Bragg peaks in Si nanocrystals. Fourier transform infrared spectroscopy studies showed that the coated films present higher chemical reactivity, promoting the formation of non-stoichiometric SiO₂, while the embedded films behave as a stoichiometric SiO₂ after the thermal annealing. The PL (photoluminescence) characterization showed that both embedded and coated films present emission dominated by the Quantum Confinement Effect before undergoing any thermal treatment. After annealing, the spectra were found to be modified only in the case of the coated films, due to the formation of defects in the nanocrystals/SiO₂ interface. Full article

(This article belongs to the Special Issue Silicon Photonics Components and Applications)

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3424 KiB

Open AccessArticle

Numerical Simulation of Multi-Crystalline Silicon Crystal Growth Using a Macro–Micro Coupled Method during the Directional Solidification Process

by Qingqing Lian, Weina Liu, Ri Li, Wenbo Yan, Caichi Liu, Yingxin Zhang, Longxuan Wang and Hongjian Chen

Appl. Sci. 2017, 7(1), 21; https://doi.org/10.3390/app7010021 - 26 Dec 2016

Cited by 8 | Viewed by 4762

Abstract

In this work, the crystal growth of multi-crystalline silicon (mc-Si) during the directional solidification process was studied using the cellular automaton method. The boundary heat transfer coefficient was adjusted to get a suitable temperature field and a high-quality mc-Si ingot. Under the conditions [...] Read more.

In this work, the crystal growth of multi-crystalline silicon (mc-Si) during the directional solidification process was studied using the cellular automaton method. The boundary heat transfer coefficient was adjusted to get a suitable temperature field and a high-quality mc-Si ingot. Under the conditions of top adiabatic and bottom constant heat flux, the shape of the crystal-melt interface changes from concave to convex with the decrease of the heat transfer coefficient on the side boundaries. In addition, the nuclei form at the bottom boundary while columnar crystals develop into silicon melt with amzigzag-faceted interface. The higher-energy silicon grains were merged into lower energy ones. In the end, the number of silicon grains decreases with the increase of crystal length. Full article

(This article belongs to the Special Issue Silicon Photonics Components and Applications)

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3143 KiB

Open AccessFeature PaperArticle

Optimization of Silicon MZM Fabrication Parameters for High Speed Short Reach Interconnects at 1310 nm

by Alexis Abraham, Thomas Anfray, Olivier Dubray, Daivid Fowler, Ségolène Olivier, Delphine Marris-Morini and Benoit Charbonnier

Appl. Sci. 2016, 6(12), 395; https://doi.org/10.3390/app6120395 - 29 Nov 2016

Cited by 4 | Viewed by 4944

Abstract

Optical modulators are key components to realize photonic circuits, and Mach-Zehnder modulators (MZM) are often used for high speed short reach interconnects. In order to maximize the tolerable path loss of a transmission link at a given bitrate, the MZM needs to be [...] Read more.

Optical modulators are key components to realize photonic circuits, and Mach-Zehnder modulators (MZM) are often used for high speed short reach interconnects. In order to maximize the tolerable path loss of a transmission link at a given bitrate, the MZM needs to be optimized. However, the optimization can be complex since the overall link performance depends on various parameters, and, for the MZM in particular, implies several trade-offs between efficiency, losses, and bandwidth. In this work, we propose a general and rigorous method to optimize silicon MZM. We first describe the optical link, and the numerical method used for this study. Then we present the results associated to the active region for 1310 nm applications. An analytical model is generated, and allows us to quickly optimize the p-n junction depending of the targeted performances for the MZM. Taking into account the required optical link parameters, the maximum tolerable path losses for different length of MZM is determined. By applying this method, simulations show that the optimum MZM length for 25 Gbps applications is 4 mm with an efficiency of 1.87 V·cm, 0.52 dB/mm of losses. A tolerable path loss of more than 25 dB is obtained. Full article

(This article belongs to the Special Issue Silicon Photonics Components and Applications)

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1586 KiB

Open AccessFeature PaperArticle

A Micro-Processor-Based Feedback Stabilization Scheme for High-Q, Non-Linear Silicon Resonators

by Giuseppe Cantarella and Michael J. Strain

Appl. Sci. 2016, 6(11), 316; https://doi.org/10.3390/app6110316 - 25 Oct 2016

Cited by 1 | Viewed by 3624

Abstract

Stabilization of silicon micro-resonators is a key requirement for their inclusion in larger photonic integrated circuits. In particular, thermal refractive index shift in non-linear applications can detune devices from their optimal working point. A cavity stabilization scheme using a micro-processor-based feedback control loop [...] Read more.

Stabilization of silicon micro-resonators is a key requirement for their inclusion in larger photonic integrated circuits. In particular, thermal refractive index shift in non-linear applications can detune devices from their optimal working point. A cavity stabilization scheme using a micro-processor-based feedback control loop is presented based on a local thermal heater element on-chip. Using this method, a silicon

π

-phase shifted grating with a cavity Q-factor of 40k is demonstrated to operate over an ambient temperature detuning range of 40

^{\circ}

C and injection wavelength range of

1.5

nm, nearly 3 orders of magnitude greater than the resonant cavity linewidth. Full article

(This article belongs to the Special Issue Silicon Photonics Components and Applications)

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3086 KiB

Open AccessArticle

Atomic Layer Deposition TiO₂ Films and TiO₂/SiN_x Stacks Applied for Silicon Solar Cells

by Zu-Po Yang, Hsyi-En Cheng, I-Hsuan Chang and Ing-Song Yu

Appl. Sci. 2016, 6(8), 233; https://doi.org/10.3390/app6080233 - 19 Aug 2016

Cited by 15 | Viewed by 6842

Abstract

Titanium oxide (TiO₂) films and TiO₂/SiN_x stacks have potential in surface passivation, anti-reflection coatings and carrier-selective contact layers for crystalline Si solar cells. A Si wafer, deposited with 8-nm-thick TiO₂ film by atomic layer deposition, has a [...] Read more.

Titanium oxide (TiO₂) films and TiO₂/SiN_x stacks have potential in surface passivation, anti-reflection coatings and carrier-selective contact layers for crystalline Si solar cells. A Si wafer, deposited with 8-nm-thick TiO₂ film by atomic layer deposition, has a surface recombination velocity as low as 14.93 cm/s at the injection level of 1.0 × 10¹⁵ cm⁻³. However, the performance of silicon surface passivation of the deposited TiO₂ film declines as its thickness increases, probably because of the stress effects, phase transformation, atomic hydrogen and thermal stability of amorphous TiO₂ films. For the characterization of 66-nm-thick TiO₂ film, the results of transmission electron microscopy show that the anatase TiO₂ crystallinity forms close to the surface of the Si. Secondary ion mass spectrometry shows the atomic hydrogen at the interface of TiO₂ and Si which serves for chemical passivation. The crystal size of anatase TiO₂ and the homogeneity of TiO₂ film can be deduced by the measurements of Raman spectroscopy and spectroscopic ellipsometry, respectively. For the passivating contacts of solar cells, in addition, a stack composed of 8-nm-thick TiO₂ film and a plasma-enhanced chemical-vapor-deposited 72-nm-thick SiN_x layer has been investigated. From the results of the measurement of the reflectivity and effective carrier lifetime, TiO₂/SiN_x stacks on Si wafers perform with low reflectivity and some degree of surface passivation for the Si wafer. Full article

(This article belongs to the Special Issue Silicon Photonics Components and Applications)

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Review

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5324 KiB

Open AccessFeature PaperReview

Nonlinear Silicon Photonic Signal Processing Devices for Future Optical Networks

by Cosimo Lacava, Mohamed A. Ettabib and Periklis Petropoulos

Appl. Sci. 2017, 7(1), 103; https://doi.org/10.3390/app7010103 - 20 Jan 2017

Cited by 39 | Viewed by 8105

Abstract

In this paper, we present a review on silicon-based nonlinear devices for all optical nonlinear processing of complex telecommunication signals. We discuss some recent developments achieved by our research group, through extensive collaborations with academic partners across Europe, on optical signal processing using [...] Read more.

In this paper, we present a review on silicon-based nonlinear devices for all optical nonlinear processing of complex telecommunication signals. We discuss some recent developments achieved by our research group, through extensive collaborations with academic partners across Europe, on optical signal processing using silicon-germanium and amorphous silicon based waveguides as well as novel materials such as silicon rich silicon nitride and tantalum pentoxide. We review the performance of four wave mixing wavelength conversion applied on complex signals such as Differential Phase Shift Keying (DPSK), Quadrature Phase Shift Keying (QPSK), 16-Quadrature Amplitude Modulation (QAM) and 64-QAM that dramatically enhance the telecom signal spectral efficiency, paving the way to next generation terabit all-optical networks. Full article

(This article belongs to the Special Issue Silicon Photonics Components and Applications)

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14310 KiB

Open AccessFeature PaperReview

Photonic Packaging: Transforming Silicon Photonic Integrated Circuits into Photonic Devices

by Lee Carroll, Jun-Su Lee, Carmelo Scarcella, Kamil Gradkowski, Matthieu Duperron, Huihui Lu, Yan Zhao, Cormac Eason, Padraic Morrissey, Marc Rensing, Sean Collins, How Yuan Hwang and Peter O’Brien

Appl. Sci. 2016, 6(12), 426; https://doi.org/10.3390/app6120426 - 15 Dec 2016

Cited by 162 | Viewed by 30508

Abstract

Dedicated multi-project wafer (MPW) runs for photonic integrated circuits (PICs) from Si foundries mean that researchers and small-to-medium enterprises (SMEs) can now afford to design and fabricate Si photonic chips. While these bare Si-PICs are adequate for testing new device and circuit designs [...] Read more.

Dedicated multi-project wafer (MPW) runs for photonic integrated circuits (PICs) from Si foundries mean that researchers and small-to-medium enterprises (SMEs) can now afford to design and fabricate Si photonic chips. While these bare Si-PICs are adequate for testing new device and circuit designs on a probe-station, they cannot be developed into prototype devices, or tested outside of the laboratory, without first packaging them into a durable module. Photonic packaging of PICs is significantly more challenging, and currently orders of magnitude more expensive, than electronic packaging, because it calls for robust micron-level alignment of optical components, precise real-time temperature control, and often a high degree of vertical and horizontal electrical integration. Photonic packaging is perhaps the most significant bottleneck in the development of commercially relevant integrated photonic devices. This article describes how the key optical, electrical, and thermal requirements of Si-PIC packaging can be met, and what further progress is needed before industrial scale-up can be achieved. Full article

(This article belongs to the Special Issue Silicon Photonics Components and Applications)

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