2019
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R Marchetti, C Lacava, L E E Carroll, K Gradkowski, P Minzioni Coupling strategies for silicon photonics integrated chips [invited] Journal Article Photonics Research, 7 (2), pp. 201–239, 2019. Abstract | Links | Tags: coupling, granting coupler, Silicon photonics, surface coupler @article{Marchetti2019,
title = {Coupling strategies for silicon photonics integrated chips [invited]},
author = {R Marchetti and C Lacava and L E E Carroll and K Gradkowski and P Minzioni},
doi = {10.1364/PRJ.7.000201},
year = {2019},
date = {2019-01-01},
journal = {Photonics Research},
volume = {7},
number = {2},
pages = {201--239},
abstract = {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 fiber-to-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.},
keywords = {coupling, granting coupler, Silicon photonics, surface coupler},
pubstate = {published},
tppubtype = {article}
}
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 fiber-to-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. |
I Demirtzioglou, C Lacava, A Shakoor, A Khokhar, Y Jung, D J Thomson, P Petropoulos Apodized silicon photonic grating couplers for mode-order conversion Journal Article Photonics Research, 7 (9), pp. 1036–1041, 2019. Abstract | Links | Tags: coupler, intermodal, multimode, silicon, Silicon photonics, surface coupler, surface gratings @article{Demirtzioglou2019,
title = {Apodized silicon photonic grating couplers for mode-order conversion},
author = {I Demirtzioglou and C Lacava and A Shakoor and A Khokhar and Y Jung and D J Thomson and P Petropoulos},
doi = {10.1364/PRJ.7.001036},
year = {2019},
date = {2019-01-01},
journal = {Photonics Research},
volume = {7},
number = {9},
pages = {1036--1041},
abstract = {An out-of-plane silicon grating coupler capable of mode-order conversion at the chip–fiber interface is designed and fabricated. Optimization of the structure is performed through finite-difference time-domain simulations, and the final device is characterized through far-field profile and transmission measurements. A coupling loss of 3.1 dB to a commercial two-mode fiber is measured for a single TE0 → LP11 mode conversion grating, which includes a conversion penalty of 1.3 dB. Far-field patterns of the excited LP11 mode profile are also reported.},
keywords = {coupler, intermodal, multimode, silicon, Silicon photonics, surface coupler, surface gratings},
pubstate = {published},
tppubtype = {article}
}
An out-of-plane silicon grating coupler capable of mode-order conversion at the chip–fiber interface is designed and fabricated. Optimization of the structure is performed through finite-difference time-domain simulations, and the final device is characterized through far-field profile and transmission measurements. A coupling loss of 3.1 dB to a commercial two-mode fiber is measured for a single TE0 → LP11 mode conversion grating, which includes a conversion penalty of 1.3 dB. Far-field patterns of the excited LP11 mode profile are also reported. |
P Minzioni, C Lacava, T Tanabe, J Dong, X Hu, G Csaba, W Porod, G Singh, A E Willner, A Almaiman, J Laurat, J Nunn Roadmap on all-optical processing Journal Article Journal of Optics (United Kingdom), 21 (6), 2019. Abstract | Links | Tags: silicon nitride, Silicon photonics, surface coupler, transceiver, wavelength conversion, wavelength converter @article{Minzioni2019,
title = {Roadmap on all-optical processing},
author = {P Minzioni and C Lacava and T Tanabe and J Dong and X Hu and G Csaba and W Porod and G Singh and A E Willner and A Almaiman and J Laurat and J Nunn},
doi = {10.1088/2040-8986/ab0e66},
year = {2019},
date = {2019-01-01},
journal = {Journal of Optics (United Kingdom)},
volume = {21},
number = {6},
abstract = {The ability to process optical signals without passing into the electrical domain has always attracted the attention of the research community. Processing photons by photons unfolds new scenarios, in principle allowing for unseen signal processing and computing capabilities. Optical computation can be seen as a large scientific field in which researchers operate, trying to find solutions to their specific needs by different approaches; although the challenges can be substantially different, they are typically addressed using knowledge and technological platforms that are shared across the whole field. This significant know-how can also benefit other scientific communities, providing lateral solutions to their problems, as well as leading to novel applications. The aim of this Roadmap is to provide a broad view of the state-of-the-art in this lively scientific research field and to discuss the advances required to tackle emerging challenges, thanks to contributions authored by experts affiliated to both academic institutions and high-tech industries. The Roadmap is organized so as to put side by side contributions on different aspects of optical processing, aiming to enhance the cross-contamination of ideas between scientists working in three different fields of photonics: optical gates and logical units, high bit-rate signal processing and optical quantum computing. The ultimate intent of this paper is to provide guidance for young scientists as well as providing research-funding institutions and stake holders with a comprehensive overview of perspectives and opportunities offered by this research field.},
keywords = {silicon nitride, Silicon photonics, surface coupler, transceiver, wavelength conversion, wavelength converter},
pubstate = {published},
tppubtype = {article}
}
The ability to process optical signals without passing into the electrical domain has always attracted the attention of the research community. Processing photons by photons unfolds new scenarios, in principle allowing for unseen signal processing and computing capabilities. Optical computation can be seen as a large scientific field in which researchers operate, trying to find solutions to their specific needs by different approaches; although the challenges can be substantially different, they are typically addressed using knowledge and technological platforms that are shared across the whole field. This significant know-how can also benefit other scientific communities, providing lateral solutions to their problems, as well as leading to novel applications. The aim of this Roadmap is to provide a broad view of the state-of-the-art in this lively scientific research field and to discuss the advances required to tackle emerging challenges, thanks to contributions authored by experts affiliated to both academic institutions and high-tech industries. The Roadmap is organized so as to put side by side contributions on different aspects of optical processing, aiming to enhance the cross-contamination of ideas between scientists working in three different fields of photonics: optical gates and logical units, high bit-rate signal processing and optical quantum computing. The ultimate intent of this paper is to provide guidance for young scientists as well as providing research-funding institutions and stake holders with a comprehensive overview of perspectives and opportunities offered by this research field. |
2015
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A Bozzola, L Carroll, D Gerace, I Cristiani, L C Andreani Optimising apodized grating couplers in a pure SOI platform to -0.5 dB coupling efficiency Journal Article Optics Express, 23 (12), pp. 16289–16304, 2015. Abstract | Links | Tags: coupler, Silicon photonics, surface coupler, surface gratings @article{Bozzola2015,
title = {Optimising apodized grating couplers in a pure SOI platform to -0.5 dB coupling efficiency},
author = {A Bozzola and L Carroll and D Gerace and I Cristiani and L C Andreani},
doi = {10.1364/OE.23.016289},
year = {2015},
date = {2015-01-01},
journal = {Optics Express},
volume = {23},
number = {12},
pages = {16289--16304},
abstract = {We present a theoretical optimisation of 1D apodized grating couplers in a "pure" Silicon-On-Insulator (SOI) architecture, i.e. without any bottom reflector element, by means of a general mutative method. We perform a comprehensive 2D Finite Difference Time Domain study of chirped and apodized grating couplers in 220 nm SOI, and demonstrate that the global maximum coupling efficiency in that platform is capped to 65% (-1.9 dB). Moving to designs with thicker Si-layers, we identify a new record design in 340 nm SOI, with a simulated coupling efficiency of 89% (-0.5 dB). Going to thicker Si layers does not further improve the efficiency, implying that -0.5 dB may be a global maximum for a grating coupler in SOI without a bottom-reflector. Even after allowing for 193 nm UV-lithographic fabrication constraints, the 340 nm design still offers -0.7 dB efficiency. These new apodized designs are the first pure SOI couplers compatible with deep-UV lithography to offer better than -1 dB insertion losses.With only very minor changes to existing deposition and lithography recipes, they are compatible with the multi-project wafer runs already offered by Si-Photonics foundries.},
keywords = {coupler, Silicon photonics, surface coupler, surface gratings},
pubstate = {published},
tppubtype = {article}
}
We present a theoretical optimisation of 1D apodized grating couplers in a "pure" Silicon-On-Insulator (SOI) architecture, i.e. without any bottom reflector element, by means of a general mutative method. We perform a comprehensive 2D Finite Difference Time Domain study of chirped and apodized grating couplers in 220 nm SOI, and demonstrate that the global maximum coupling efficiency in that platform is capped to 65% (-1.9 dB). Moving to designs with thicker Si-layers, we identify a new record design in 340 nm SOI, with a simulated coupling efficiency of 89% (-0.5 dB). Going to thicker Si layers does not further improve the efficiency, implying that -0.5 dB may be a global maximum for a grating coupler in SOI without a bottom-reflector. Even after allowing for 193 nm UV-lithographic fabrication constraints, the 340 nm design still offers -0.7 dB efficiency. These new apodized designs are the first pure SOI couplers compatible with deep-UV lithography to offer better than -1 dB insertion losses.With only very minor changes to existing deposition and lithography recipes, they are compatible with the multi-project wafer runs already offered by Si-Photonics foundries. |
2014
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L Carroll, D Gerace, I Cristiani, L C Andreani Optimizing polarization-diversity couplers for Si-photonics: Reaching the -1dB coupling efficiency threshold Journal Article Optics Express, 22 (12), pp. 14769–14781, 2014. Abstract | Links | Tags: Silicon photonics, surface coupler, surface gratings @article{Carroll2014,
title = {Optimizing polarization-diversity couplers for Si-photonics: Reaching the -1dB coupling efficiency threshold},
author = {L Carroll and D Gerace and I Cristiani and L C Andreani},
doi = {10.1364/OE.22.014769},
year = {2014},
date = {2014-01-01},
journal = {Optics Express},
volume = {22},
number = {12},
pages = {14769--14781},
abstract = {Polarization-diversity couplers are low-cost industrially-scalable passive devices that can couple light of unknown polarization from a telecom fiber-mode to a pair of TE-polarized wave-guided modes in the Silicon-on-Insulator platform. These couplers offer significantly more relaxed alignment tolerances than edge-coupling schemes, which is advantageous for commercial fiber-packaging of Si-photonic circuits. However, until now, polarization-diversity couplers have not offered sufficient coupling efficiency to motivate serious commercial consideration. Using 3D finite difference time domain calculations for device optimization, we identify Silicon-on-Insulator polarization-diversity couplers with 1550nm coupling efficiencies of 0.95dB and 1.9dB, for designs with and without bottom-reflector elements, respectively. These designs offer a significant improvement over state-of-the-art performance, and effectively bridge the "performance gap" between polarizationdiversity couplers and 1D-grating couplers. Our best polarization-diversity coupler design goes beyond the 1dB efficiency limit that is typically accepted as the minimum needed for industrial adoption of coupler devices in the telecoms market. textcopyright 2014 Optical Society of America.},
keywords = {Silicon photonics, surface coupler, surface gratings},
pubstate = {published},
tppubtype = {article}
}
Polarization-diversity couplers are low-cost industrially-scalable passive devices that can couple light of unknown polarization from a telecom fiber-mode to a pair of TE-polarized wave-guided modes in the Silicon-on-Insulator platform. These couplers offer significantly more relaxed alignment tolerances than edge-coupling schemes, which is advantageous for commercial fiber-packaging of Si-photonic circuits. However, until now, polarization-diversity couplers have not offered sufficient coupling efficiency to motivate serious commercial consideration. Using 3D finite difference time domain calculations for device optimization, we identify Silicon-on-Insulator polarization-diversity couplers with 1550nm coupling efficiencies of 0.95dB and 1.9dB, for designs with and without bottom-reflector elements, respectively. These designs offer a significant improvement over state-of-the-art performance, and effectively bridge the "performance gap" between polarizationdiversity couplers and 1D-grating couplers. Our best polarization-diversity coupler design goes beyond the 1dB efficiency limit that is typically accepted as the minimum needed for industrial adoption of coupler devices in the telecoms market. textcopyright 2014 Optical Society of America. |
