Subwavelength Grating Metamaterial Waveguides and Ring Resonators on a Silicon Nitride Platform

Naraine, Cameron M.; Westwood‐Bachman, Jocelyn N.; Horvath, Cameron; Aktary, Mirwais; Knights, Andrew P.; Schmid, Jens H.; Cheben, Pavel; Bradley, Jonathan D. B.

doi:10.1002/lpor.202200216

Cited by 9 publications

(4 citation statements)

References 37 publications

(63 reference statements)

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“…Silicon nitride (SiN) is a versatile and mature waveguide platform to implement low-cost photonic building blocks [27][28][29][30] by leveraging well-developed manufacturing of Si CMOS microelectronics. SiN also provide low-loss waveguides, improved tolerance to fabrication errors, reduced polarization sensitivity, enhanced high-power handling, and wide transparency window.…”

Section: Silicon Nitride Grating Couplersmentioning

confidence: 99%

Silicon-based surface gratings for efficient fiber-chip and free-space beam coupling

Benedikovič

Fraser

Korcek

et al. 2023

Integrated Optics: Design, Devices, Systems and Applications VII

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Silicon photonics has established itself as a key integration platform, leveraging high-quality materials and large-scale manufacturing using mastered toolsets of complementary metal-oxide-semiconductor (CMOS) foundries. Chip-scale photonics offer unique promises for dense integration of versatile optical functions through compact and high-performance building blocks. Integrated photonics is now competing technology for many applications, spanning from telecom/datacom and interconnects up to quantum sciences and light detection and ranging (LIDAR) systems, among others. However, the lack of low-loss input/output chip interfaces can be prohibitive to successfully deploy multi-diverse device applications. Low coupling loss is essential in reducing overall power budget in photonic systems, impacting on-chip integration level. The light coupling from an off-chip environment into the planar waveguide platforms has always been a challenging research problem since the early years of integrated photonics. Optical interfaces formed on a photonic chip surface, rather than implemented on a chip edge, have been widely used to access photonic circuits with optical fibers or enabling free-space coupling of light beams. Surface gratings can be positioned at arbitrary locations and/or arranged in pre-defined patterns on the chip, facilitating wafer-scale testing and optical packaging. In this work, we present our recent progress in the development of silicon-based surface gratings for use in fiber-to-chip and free-space beam coupling. In particular, we discuss prospective design approaches to develop low-loss surface grating couplers implemented on silicon-on-insulator (SOI), silicon nitride (SiN), and hybrid silicon-silicon nitride (Si-SiN) platforms, allowing to approach a coupling loss below -1 dB. Among these, we also cover contemporary advances in compact silicon metamaterial nano-antennas for dense optical phased arrays, obtaining high a diffraction performance (> 90%) and wideband operation (> 200 nm) simultaneously.

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Section: Silicon Nitride Grating Couplersmentioning

confidence: 99%

Silicon-based surface gratings for efficient fiber-chip and free-space beam coupling

Benedikovič

Fraser

Korcek

et al. 2023

Integrated Optics: Design, Devices, Systems and Applications VII

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“…The Si3N4 takes advantages of a broadband transparency, well-established deposition techniques, and a lower index contrast. So far, a wide range of chip-integrated building blocks has been developed and demonstrated, including ultra-low-loss and dispersion-engineered waveguides [4,5], splitters [6], resonators [7], filters [8], modulators [9] and fiber-chip grating and edge couplers [10][11][12][13], to name a few. The index contrast between the Si3N4 core and the claddings is low, therefore it is still an important design objective to realize efficient connections between the outside world and Si3N4 chips.…”

Section: Introductionmentioning

confidence: 99%

High-efficiency off-chip grating couplers for silicon nitride photonics

Korcek,

Fraser,

Wilmart

et al. 2024

Integrated Optics: Devices, Materials, and Technologies XXVIII

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Silicon nitride (Si3N4) is a leading platform in integrated photonics, providing unique passive functionalities, while maintaining compatibility with complementary metal-oxide-semiconductor processes and scalable and low-cost highvolume production. However, the moderate index contrast of the Si3N4 platform makes it difficult to implement efficient vertical surface grating couplers. In this work, we present efficient and robust fiber-chip grating couplers on native and hybrid Si3N4 platforms. Minimum coupling losses between -5 dB and -3 dB were measured for single-etch fabricated devices near 1.55 μm wavelength. Moreover, by leveraging the amorphous-silicon overlay on top of the Si3N4 platform, we develop hybrid single-etch grating couplers, with a coupling loss approaching 1 dB. The demonstrated grating couplers are promising for SiN integrated photonics, enabling a rapid and cost-effective chip interfacing with standard optical fibers. This opens up novel opportunities for rising applications, including optical communications, nonlinear optics, or quantum information sciences.

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“…The low refractive index contrast enhances robustness to fabrication imperfections and has led to the demonstration of ultra-low propagation losses 8 . State-of-the-art photonic structures and devices have been demonstrated on the SiN platform, including waveguides 9 , filters 10 , splitters 11 , ring resonators 12 and on- and off-chip waveguide couplers 13 , among others.…”

Section: Introductionmentioning

confidence: 99%

High-efficiency self-focusing metamaterial grating coupler in silicon nitride with amorphous silicon overlay

Fraser,

Benedikovic,

Korcek

et al. 2024

Sci Rep

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Efficient fiber-chip coupling interfaces are critically important for integrated photonics. Since surface gratings diffract optical signals vertically out of the chip, these couplers can be placed anywhere in the circuit allowing for wafer-scale testing. While state-of-the-art grating couplers have been developed for silicon-on-insulator (SOI) waveguides, the moderate index contrast of silicon nitride (SiN) presents an outstanding challenge for implementing efficient surface grating couplers on this platform. Due to the reduced grating strength, a longer structure is required to radiate the light from the chip which produces a diffracted field that is too wide to couple into the fiber. In this work, we present a novel grating coupler architecture for silicon nitride photonic integrated circuits that utilizes an amorphous silicon (α-Si) overlay. The high refractive index of the α-Si overlay breaks the coupler’s vertical symmetry which increases the directionality. We implement subwavelength metamaterial apodization to optimize the overlap of the diffracted field with the optical fiber Gaussian mode profile. Furthermore, the phase of the diffracted beam is engineered to focalize the field into an SMF-28 optical fiber placed 55 µm above the surface of the chip. The coupler was designed using rigorous three-dimensional (3D) finite-difference time-domain (FDTD) simulations supported by genetic algorithm optimization. Our grating coupler has a footprint of 26.8 × 32.7 µm2 and operates in the O-band centered at 1.31 μm. It achieves a high directionality of 85% and a field overlap of 90% with a target fiber mode size of 9.2 µm at the focal plane. Our simulations predict a peak coupling efficiency of − 1.3 dB with a 1-dB bandwidth of 31 nm. The α-Si/SiN grating architecture presented in this work enables the development of compact and efficient optical interfaces for SiN integrated photonics circuits with applications including optical communications, sensing, and quantum photonics.

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Subwavelength Grating Metamaterial Waveguides and Ring Resonators on a Silicon Nitride Platform

Cited by 9 publications

References 37 publications

Silicon-based surface gratings for efficient fiber-chip and free-space beam coupling

Silicon-based surface gratings for efficient fiber-chip and free-space beam coupling

High-efficiency off-chip grating couplers for silicon nitride photonics

High-efficiency self-focusing metamaterial grating coupler in silicon nitride with amorphous silicon overlay

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