Unidirectionally optical coupling from free space into silicon waveguide with wide flat-top angular efficiency

Li, Kun; Li, Guangyuan; Xiao, Feng; Lu, Fan; Wang, Zhonghua; Xu, Anshi

doi:10.1364/oe.20.018545

Cited by 8 publications

(3 citation statements)

References 25 publications

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“…These excitation, reflection, and transmittance coefficients are all associated with the scattering components of an electromagnetic field. The concepts of the zero field, scattered field, and total field have been introduced in our previous work [19][20][21], i.e., the zero field is the field when there are no scatterers at all, and the scattered field is calculated by subtracting the zero field from the total field with scatterers. Since σ , R and T can be calculated recursively starting from β 1 , ρ 1 and τ 1 , the geometry optimization for N periodic indentations is reduced into that for a single one, resulting in a great reduction of the computational cost.…”

Section: Theory and Principle Of Operationmentioning

confidence: 99%

Compact plasmonic dichroic splitting with high splitting ratio based on a cascaded-grating structure

Xiao

et al. 2014

J. Opt. Soc. Am. B

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A compact dichroic surface plasmon polariton (SPP) splitting scheme composed of two cascaded subgratings of different dimensions is proposed and investigated. The normal incident photons illuminated on the dichroic splitting structure are converted to surface plasmons traveling to the left or right depending on the wavelength. The operation principle is clarified and a coupled-mode model is developed to facilitate structure design. The generated SPPs propagating to the left and right directions on the metal surface can be manipulated nearly independently by altering the left and right subgrating, respectively. Proof-of-principle demonstrations show that a remarkable property of high splitting ratios is achieved with 43.0 dB at wavelength 1310 nm (left:right power contrast) and 35.7 dB at wavelength 1550 nm (right:left power contrast). The proposed splitting concept has general applicability across other operating wavelengths, such as the visible and near-infrared range

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Section: Theory and Principle Of Operationmentioning

confidence: 99%

Compact plasmonic dichroic splitting with high splitting ratio based on a cascaded-grating structure

Xiao

et al. 2014

J. Opt. Soc. Am. B

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“…Instead, here we develop a cascaded grating based on the coupled-mode theory to circumvent this problem. Quite recently, we discovered that cascading two gratings that are of proper interval between their peak angular efficiencies will lead to wide flat-top and wide angular FWHM for coupling free-space light into silicon waveguide [16]. Analogously, the spectral FWHM may also be broadened by cascading gratings with a suitable spectral interval.…”

Section: Structure and Operation Principlementioning

confidence: 99%

Unidirectional optical coupling for plasmonic waveguide based on metallic-dielectric high-contrast gratings

Wang

et al. 2014

SPIE Proceedings

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Based on the metallic-dielectric high contrast gratings, we proposed two new different schemes to achieve the unidirectional coupling of incident free-space light into the plasmonic waveguides. Using the cascaded metal-air subgratings (structure 1) or metallic-dielectric subwavelength periodic gratings (structure 2), the ultra-broadband and wideangular SPPs excitation could be both achieved. The operation principle and performance of the structures are analyzed and discussed, respectively.

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“…a single scattering ridge or slit in a metallic film [13,14], can provide broadband or angle-insensitive free-space radiation to SPP modes coupling, it is not conducive to practical implementations due to relatively low efficiency. Recently, some of our authors demonstrated that cascading two silicon gratings that are of a proper angular interval between their peak efficiencies can lead to a wide flat-top angular coupling efficiency into dielectric waveguide [15]. While this silicon coupler has superior wide-angle performance, its bandwidth is somewhat limited due to a narrow operating wavelength (λ = 1.55 µm) and the silicon-based composition is not suitable for broadband sensing.…”

Section: Introductionmentioning

confidence: 99%

Unidirectional coupling of surface plasmons with ultra-broadband and wide-angle efficiency: potential applications in sensing

Xiao

et al. 2013

New J. Phys.

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A cascaded-grating coupling scheme for unidirectionally coupling and launching surface plasmons from free-space light with ultra-broadband and wide-angle efficiency is proposed and theoretically investigated, and the potential applications in sensing are discussed. The cascaded sub-gratings of different periods couple the incident light over a relatively wide wavelength and angular range into surface plasmon polaritons (SPPs). After traveling a short distance, the SPPs interact with the sensed medium, and then are coupled back into freely propagating light through the nanoslit in the metal film. By observing the changes of SPP-mediated light coupled out through the slit, broadband sensing is achieved. A quantitative theoretical model is developed for performance prediction and validated with aperiodic Fourier modal method. Proof-of-principle demonstrations show that the spectral 3 full-width-half-maximum reaches 400 nm and meanwhile the angular width is up to 25 • , both of which are almost four times compared to the reference singleperiodic gratings. A wavelength sensitivity as high as 852 nm RIU −1 (RIU, refractive index units) and a relative intensity change up to ∼5 × 10 4 % RIU −1 are obtained. Contents

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Unidirectionally optical coupling from free space into silicon waveguide with wide flat-top angular efficiency

Cited by 8 publications

References 25 publications

Compact plasmonic dichroic splitting with high splitting ratio based on a cascaded-grating structure

Compact plasmonic dichroic splitting with high splitting ratio based on a cascaded-grating structure

Unidirectional optical coupling for plasmonic waveguide based on metallic-dielectric high-contrast gratings

Unidirectional coupling of surface plasmons with ultra-broadband and wide-angle efficiency: potential applications in sensing

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