High-efficiency reflector-less dual-level silicon photonic grating coupler

Vitali, Valerio; Bucio, Thalía Domínguez; Lacava, Cosimo; Marchetti, R.; Mastronardi, Lorenzo; Rutirawut, Teerapat; Churchill, G. B.; Faneca, Joaquín; Gates, James C.; Gardès, Frédéric; Petropoulos, P.

doi:10.1364/prj.488970

Cited by 8 publications

(3 citation statements)

References 48 publications

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“…Due to the fully etched grating design, the devices can be fabricated using one or two lithographic masks, making misalignment less of an issue. Designs requiring 3 lithographic processes are more affected by misalignment issues, a study about its impact must then be conducted [29].…”

Section: Final Discussionmentioning

confidence: 99%

“…To simplify the etching process, we designed a fully etched grating coupler (i.e. the silicon layer is etched down to the substrate) in alternative to the more common partially etched designs, requiring two lithographic masks [25], [26] or even more [27]- [29].…”

Section: Light Coupler Designmentioning

confidence: 99%

“…Without apodization, the grating couplers exhibit an exponential decay of the diffracted field over its length [32], Figure 2a, due to this fact most authors tend to prefer designs employing some form of apodization [26], [29], [33]. With this technique, the diffracted field distribution becomes more like a gaussian throughout the grating coupler's section [32], the field distribution commonly found in optical fibers, Figure 2b, resulting in more efficient coupling.…”

Section: Grating Coupler Optimizationmentioning

confidence: 99%

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Amorphous silicon grating couplers based on random and quadratic variation of the refractive index

Almeida,

Rossi,

Lourenço

et al. 2024

Physics and Simulation of Optoelectronic Devices XXXII

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An increasing number of integrated photonic solutions find applications in the fields of biomedicine, manufacture, quantum computation and telecommunications. Size mismatch between optical fibers, light sources, photodetectors and photonic waveguides is usually significant, typically with the former having cross-sections on the orders of hundreds of micrometers or more and the latter a few micrometers or hundreds of nanometers. Efficiency in coupling light to and from photonic integrated circuits is an extremely important parameter since it influences device's performance, affecting signal-to-noise ratio. Several approaches exist for light coupling, such as off-plane coupling with the assistance of grating couplers, onplane/edge coupling with or without the assistance of tapers and adiabatic coupling. In this study we focus on grating couplers designed in amorphous silicon-on-insulator (SOI) platforms. Grating couplers are compact, can be tested at waferlevel, and do not require application specific fiber terminations, such as lenses and/or tapers. Two approaches in the optimization of grating couplers were explored, one based on a lithographic mask defined by the superposition of two different grating patterns, with different periods, having an offset to provide a random distribution of grating elements, and a technique based on the quadratic variation of the refractive index of the grating structure along its length. Results were obtained from 2D-FDTD simulations. Coupling efficiencies for the quasi-TE mode over -13 dB and -3 dB were obtained for the random and quadratic variations of the effective refractive index at a wavelength of 1550 nm, without bottom reflectors.

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Section: Final Discussionmentioning

confidence: 99%

Section: Light Coupler Designmentioning

confidence: 99%

Section: Grating Coupler Optimizationmentioning

confidence: 99%

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Amorphous silicon grating couplers based on random and quadratic variation of the refractive index

Almeida,

Rossi,

Lourenço

et al. 2024

Physics and Simulation of Optoelectronic Devices XXXII

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Silicon photonics for high-speed communications and photonic signal processing

Zhou,

Yi,

Chan

et al. 2024

npj Nanophoton.

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Leveraging on the mature processing infrastructure of silicon microelectronics, silicon photonic integrated circuits may be readily scaled to large volume production for low-cost high-volume applications such as optical transceivers for data centers. Driven by the rapid growth of generative artificial intelligence and the resultant rapid increase in data traffic in data centers, new integrated optical transceivers will be needed to support multichannel high-capacity communications beyond 1.6Tb/s. In this paper, we review some of the recent advances in high performance optical waveguide grating couplers (WGC) as a key enabling technology for future high capacity communications. We describe the novel use of shifted-polysilicon overlay gratings on top of the silicon grating that enabled foundry manufactured chips to have fiber-chip coupling losses of under 1 dB. The use of mirror symmetry and resonant cavity enhancement in the design of gratings can increase the 1-dB optical bandwidths of grating couplers to over 100 nm. Multimode waveguide grating couplers (MWGC) may be designed for the selective launch of different modes channels in multimode fibers for mode-division-multiplexing (MDM) communications. The use of different modes or polarizations in optical fibers for high capacity communications requires the unscrambling of data lanes which are mixed together during the optical fiber transmission. We describe how silicon photonic circuits can be used to perform unitary matrix operations and unscramble the different data lanes in multichannel optical communication systems. We also describe recent advances on high-speed silicon modulators for enabling data rates of individual data lanes in an integrated optical transceiver beyond 300 Gb/s.

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