A compact silicon grating coupler based on hollow tapered spot-size converter

Asaduzzaman,; Bakaul, Masuduzzaman; Skafidas, Efstratios; Khandokar, Rezwanul Haque

doi:10.1038/s41598-018-20875-3

Cited by 17 publications

(11 citation statements)

References 42 publications

(27 reference statements)

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“…Since it is inefficient to find an excellent design by full parameters sweeping, we alternatively resort to optimization algorithms in our design. Among various optimization algorithms, particle swarm optimization (PSO) has been widely used in the optimization of a myriad of optical waveguide devices, e.g., waveguide crossing 43 , optical phased arrays 44 , compact silicon grating coupler 45 . Initially, several simulations with different coefficients were performed using the standard PSO (SPSO) setup, and the results were always fluid.…”

Section: Resultsmentioning

confidence: 99%

Crosstalk reduction of integrated optical waveguides with nonuniform subwavelength silicon strips

Yang

Guo

Huang

et al. 2020

Sci Rep

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Suppression of the crosstalk between adjacent waveguides is important yet challenging in the development of compact and dense photonic integrated circuits (PICs). During the past few years, a few of excellent approaches have been proposed to achieve this goal. Here, we propose a novel strategy by introducing nonuniform subwavelength strips between adjacent waveguides. In order to determine the widths and positions of nonuniform subwavelength strips, the particle swarm optimization (PSO) algorithm is utilized. Numerical results demonstrate that the coupling length between adjacent waveguides is increased by three (five) orders of magnitude in comparison with the case of uniform (no) subwavelength strips. Our method greatly reduces crosstalk and is expected to achieve a highly compact integrated density of PICs.

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Section: Resultsmentioning

confidence: 99%

Crosstalk reduction of integrated optical waveguides with nonuniform subwavelength silicon strips

Yang

Guo

Huang

et al. 2020

Sci Rep

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“…The reflectance and spectra were calculated by using C-language programing. For design and optimization of the grating coupler with a bottom multilayer reflector, we used the two-dimensional (2D) finite difference time domain method (FDTD) by using the commercial software Rsoft 8,11,12,26 .…”

Section: Methodsmentioning

confidence: 99%

“…In order to obtain wafer-scale testing flexibility and facile coupling operation, waveguide grating couplers have been used in Si and SiN x PICs 6–12 . Compared to a silicon grating coupler, SiN x grating couplers have a lower coupling efficiency due to a lower index contrast 2,9,13 .…”

Section: Introductionmentioning

confidence: 99%

“…One of the problems is that a majority of the optical power is reflected downward into the substrate and dissipates. Bottom reflectors such as a metal mirror 12,14 and distributed Bragg reflector 3,9,15 have been utilized to improve the coupling efficiency of silicon and silicon nitride grating couplers. Linear silicon grating reflectors have also been adopted to achieve a higher directionality 2,16 .…”

Section: Introductionmentioning

confidence: 99%

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A high efficiency silicon nitride waveguide grating coupler with a multilayer bottom reflector

Hong

Spring

Qiu

et al. 2019

Sci Rep

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We propose a high efficiency apodized grating coupler with a bottom reflector for silicon nitride photonic integrated circuits. The reflector consists of a stack of alternate silicon nitride and silicon dioxide quarter-wave films. The design, fabrication and optical characterization of the couplers has been presented. The measured fiber to detector insertion loss was −3.5 dB which corresponds to a peak coupling efficiency of −1.75 dB. A 3 dB wavelength bandwidth of 76.34 nm was demonstrated for the grating coupler with a 20-layer reflector. The fabrication process is CMOS-compatible and requires only a single etching step.

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“…Segmented-stepwise taper with a length of 20 µm has been designed to connect a 12 µm-wide waveguide to a 0.5 µm one with a maximum coupling loss of 0.5 dB [19]. 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.…”

Section: Introductionmentioning

confidence: 99%

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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A compact silicon grating coupler based on hollow tapered spot-size converter

Cited by 17 publications

References 42 publications

Crosstalk reduction of integrated optical waveguides with nonuniform subwavelength silicon strips

Crosstalk reduction of integrated optical waveguides with nonuniform subwavelength silicon strips

A high efficiency silicon nitride waveguide grating coupler with a multilayer bottom reflector

Ultrashort waveguide tapers based on Luneburg lens

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