Design and fabrication of a single leakage-channel grating coupler

Roncone, Ronald L.; Li, Lifeng; Bates, Keith A.; Burke, James J.; Weisenbach, Lori; Zelinski, Brian J.J.

doi:10.1364/ao.32.004522

Cited by 31 publications

(10 citation statements)

References 15 publications

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“…This could also lead to increased efficiency of grating couplers for silicon photonics and light detection and ranging (LI-DAR) devices. Previous designs of grating couplers have achieved a top-down asymmetry ratio (defined as the ratio of power going to the top and to the bottom) of up to 50:1 [8][9][10]12], but they typically make use of a substrate reflector or involve multiple layers and grooves [13], which complicate fabrication and could be difficult to scale to larger areas if desired. Asymmetric out-of-plane emission from photonic crystal defect cavities of 4:1 has also been demonstrated [14], but all these works were guided primarily by numerical optimization.…”

Section: Introductionmentioning

confidence: 99%

Perfect single-sided radiation and absorption without mirrors

Zhou

Zhen

Hsu

et al. 2016

Optica

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Highly directional radiation from photonic structures is important for many applications, including high power photonic crystal surface emitting lasers, grating couplers, and light detection and ranging devices. However, previous dielectric, few-layer designs only achieved moderate asymmetry ratios, and a fundamental understanding of bounds on asymmetric radiation from arbitrary structures is still lacking. Here, we show that breaking the 180• rotational symmetry of the structure is crucial for achieving highly asymmetric radiation. We develop a general temporal coupled-mode theory formalism to derive bounds on the asymmetric decay rates to the top and bottom of a photonic crystal slab for a resonance with arbitrary in-plane wavevector. Guided by this formalism, we show that infinite asymmetry is still achievable even without the need of back-reflection mirrors, and we provide numerical examples of designs that achieve asymmetry ratios exceeding 10 4 . The emission direction can also be rapidly switched from top to bottom by tuning the wavevector or frequency. Furthermore, we show that with the addition of weak material absorption loss, such structures can be used to achieve perfect absorption with single-sided illumination, even for single-pass material absorption rates less than 0.5% and without back-reflection mirrors. Our work provides new design principles for achieving highly directional radiation and perfect absorption in photonics.

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Section: Introductionmentioning

confidence: 99%

Perfect single-sided radiation and absorption without mirrors

Zhou

Zhen

Hsu

et al. 2016

Optica

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“…Such highly directional radiation is essential and desirable in many optoelectronic devices. For example, grating couplers [32][33][34][35][36] , which couple light between the nanophotonic waveguides and fibers, are among the most important elements in photonic integrated circuits. While having been studied extensively, the performance of grating couplers is still far from optimal: one of the major challenges is the insertion loss that is now mainly limited by unwanted downward radiation losses 36 .…”

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confidence: 99%

Observation of topologically enabled unidirectional guided resonances

Yin

Jin

Soljačić

et al. 2020

Nature

272

152

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Unidirectional radiation is important for a variety of optoelectronic applications. Many unidirectional emitters exist, but they all rely on the use of materials or structures that forbid outgoing waves, i.e. mirrors. Here, we theoretically propose and experimentally demonstrate a class of resonances in photonic crystal slabs, which only radiate towards a single side with no mirror placed on the other side-we call them "unidirectional bound states in the continuum". These resonances are found to emerge when a pair of half-integer topological charges in the polarization field bounce into each other in the momentum space. We experimentally demonstrate such resonances in the telecommunication regime, where we achieve single-sided quality factor as high as 1.6 × 10 5 , equivalent to a radiation asymmetry ratio of 27.7 dB. Our work represents a vivid example of applying topological principles to improve optoelectronic devices. Possible applications of our work include grating couplers, photoniccrystal surface-emitting lasers, and antennas for light detection and ranging. Topological defects 1 , characterized by quantized invariants, offer a general picture to un-1

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“…The existence of the evanescent field within the upper cladding of SS-BRWs allows the investigation of efficient coupling techniques, particularly grating-assisted coupling. Investigation of integrated grating couplers has been extensively carried out in semiconductor waveguides and is not the focus of this paper [9][10][11]. However, an important waveguide parameter that is closely related to the design of a grating coupler and waveguide nonlinear properties is the thickness of the upper cladding, t cladd .…”

Section: A Second-harmonic Generationmentioning

confidence: 99%

“…Owing to the oscillatory nature of the Bragg mode field profile, conventional coupling techniques, such as freespace coupling and fiber coupling, result in poor spatial overlap factor between the incident pump beam and the excited pump Bragg mode. More involved coupling techniques, such as prism-coupling and grating-coupling [9][10][11], which require mode excitation from above the sample, are not viable options. This is due to the existence of the upper Bragg reflector, which acts as a high reflector mirror at the pump wavelength, hence prohibiting the transfer of the incident beam energy to the waveguide core.…”

Section: Introductionmentioning

confidence: 99%

Single-sided Bragg reflection waveguides with multilayer core for monolithic semiconductor parametric devices

Abolghasem

Helmy

2012

J. Opt. Soc. Am. B

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We propose and examine single-stack matching-layer enhanced Bragg reflection waveguides (BRWs) as a platform for integrated parametric devices. The proposed designed is asymmetric in geometry, where a multilayer core is surrounded by a single-layer upper cladding and a lower quarter-wave Bragg mirror. The propagation of the Bragg mode in the new design relies on total internal reflection from the upper cladding and Bragg reflection from the lower periodic cladding. Analytical expressions for modal analysis of TE-and TM-polarized Bragg modes are derived. An Al x Ga 1−x As second-harmonic generation device is theoretically examined to highlight nonlinear performance of the new design, and it is compared to symmetric phase-matched BRWs reported to date. The application of the same structure for generation of anticorrelated photon pairs is discussed.

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Design and fabrication of a single leakage-channel grating coupler

Abstract: We describe the modelling and fabrication of waveguide grating couplers with out-

Cited by 31 publications

References 15 publications

Perfect single-sided radiation and absorption without mirrors

Perfect single-sided radiation and absorption without mirrors

Observation of topologically enabled unidirectional guided resonances

Single-sided Bragg reflection waveguides with multilayer core for monolithic semiconductor parametric devices

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