Compact broadband low-loss taper for coupling to a silicon nitride photonic wire

Sethi, Purnima; Kallega, Rakshitha; Haldar, Anubhab; Selvaraja, Shankar Kumar

doi:10.1364/ol.43.003433

Cited by 16 publications

(6 citation statements)

References 28 publications

(31 reference statements)

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“…A taper using a quadratic sinusoidal function has been designed to connect a 10 µm-wide waveguide to a 1 µm one with a length of 19.5 µm in silicon nitride (SiN) platform. This study reports a maximum 0.27 dB coupling loss in the C and L bands [17]. The same method has also been utilized in SOI platform to design a 15 µm long taper with a coupling loss lower than 0.31 dB for connecting a 10 µm-wide waveguide to a 0.5 µm single-mode silicon waveguide [18].…”

Section: Introductionmentioning

confidence: 88%

“…A hollow tapered waveguide has been introduced to reduce the lateral width of the waveguide from 15 µm to 0.3 µm at a length of 60 µm while the coupling loss is lower than 2.0 [20]. The theoretical results of [15][16][17][18][19][20] are reported in this section. Tapers based on transformation optics (TO) have also been proposed, however, the implementation of these designs require anisotropic metamaterials [21][22][23].…”

Section: Introductionmentioning

confidence: 99%

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Ultrashort waveguide tapers based on Luneburg lens

Badri

Gilarlue

2019

J. Opt.

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In integrated photonic circuits, silicon-on-insulator waveguides with different geometries have been employed to realize a variety of components. Therefore, efficient coupling of two different waveguides is crucial. In this paper, focusing property of the Luneburg lens is exploited to design waveguide tapers. The Luneburg lens, truncated in a shape of a parabolic taper with reduced footprint, is utilized to connect a 10 µm-wide waveguide to a 0.5 µm one with the same thickness with an average coupling loss of 0.35 dB in the entire O, E, S, C, L, and U bands of optical communications. The proposed compact taper with the length of 11 µm is implemented by varying the thickness of the guiding layer and compared with three conventional tapers with the same length. However, designing a coupler to connect waveguides with different thicknesses and widths is more challenging. By applying quasi-conformal transformation optics, we flatten the Luneburg lens and consequently increase the refractive index on the flattened side. As a result, we are able to couple two waveguides with different thicknesses and widths. The numerical simulations are used to evaluate the theoretically designed tapers. To our knowledge, this is the first study presenting ultrashort tapers based on truncated Luneburg lens.

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Section: Introductionmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Ultrashort waveguide tapers based on Luneburg lens

Badri

Gilarlue

2019

J. Opt.

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“…1. The proposed taper works on self-imaging principle in multi-mode waveguides along the propagating length [28,29]. The length and width of the taper are optimized to obtain interference progressively between the resonance modes along the taper resulting in maximum coupling to the fundamental waveguide mode.…”

Section: Compact Taper: Design and Simulationmentioning

confidence: 99%

“…The length and width of the taper are optimized to obtain interference progressively between the resonance modes along the taper resulting in maximum coupling to the fundamental waveguide mode. The interpolation formula used to define the proposed taper to connect a broad waveguide to a submicron waveguide section is [28,29],…”

Section: Compact Taper: Design and Simulationmentioning

confidence: 99%

Alignment-tolerant broadband compact taper for low-loss coupling to a silicon-on-insulator photonic wire waveguide

Sethi

Selvaraja

2019

Appl. Opt.

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We experimentally demonstrate a broadband, fabrication tolerant compact silicon waveguide taper (34.2 µm) in silicon-on-insulator. The taper works on multi-mode interference along the length of the taper. A single taper design has a broadband operation with coupling efficiency >70% over 700 nm that can be used in O, C and L-band. The compact taper is highly tolerant to fabrication variations; ±100 nm change in the taper and end waveguide width varies the taper transmission by <5%. The footprint of the device i.e. taper along with the linear gratings is ~ 442 m 2 ; 11.5X smaller than the adiabatic taper. The taper with linear gratings provides comparable coupling efficiency as standardly used focusing gratings. We have also compared the translational and rotational alignment tolerance of the focusing grating with the linear grating.

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“…However, the proposed structures are either difficult to fabricate, or suffer from low efficiencies and larger footprints. Recently, a novel design of large bandwidth, fabrication tolerant, CMOS-compatible and non-adiabatic compact tapers have been proposed and experimentally demonstrated in SOI (wire and ridge configuration) as well as Silicon Nitride platform [46][47][48]. These tapers along with linear gratings for spot-size conversion exhibits no degradation in the coupling efficiency compared to a standard focusing grating in 1.55 µm band.…”

Section: Linear Grating Based Compact Tapersmentioning

confidence: 99%

Grating-Assisted Fiber to Chip Coupling for SOI Photonic Circuits

2018

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Fiber to chip coupling is a critical aspect of any integrated photonic circuit. In terms of ease of fabrication as well as wafer-scale testability, surface grating couplers are by far the most preferred scheme of the coupling to integrated circuits. In the past decade, considerable effort has been made for designing efficient grating couplers on Silicon-on-Insulator (SOI) and other allied photonic platforms. Highly efficient grating couplers with sub-dB coupling performance have now been demonstrated. In this article, we review the recent advances made to develop grating coupler designs for a variety of applications on SOI platform. We begin with a basic overview of design methodology involving both shallow etched gratings and the emerging field of subwavelength gratings. The feasibility of reducing footprint by way of incorporating compact tapers is also explored. We also discuss novel grating designs like polarization diversity as well as dual band couplers. Lastly, a brief description of various packaging and wafer-scale testing schemes available for fiber-chip couplers is elaborated.

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Compact broadband low-loss taper for coupling to a silicon nitride photonic wire

Cited by 16 publications

References 28 publications

Ultrashort waveguide tapers based on Luneburg lens

Ultrashort waveguide tapers based on Luneburg lens

Alignment-tolerant broadband compact taper for low-loss coupling to a silicon-on-insulator photonic wire waveguide

Grating-Assisted Fiber to Chip Coupling for SOI Photonic Circuits

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