Plasmonic Mach–Zehnder Interferometer for Ultrasensitive On-Chip Biosensing

Gao, Yongkang; Gan, Qiaoqiang; Xin, Zheming; Cheng, Xuanhong; Bartoli, F. J.

doi:10.1021/nn2034204

Cited by 155 publications

(131 citation statements)

References 52 publications

(112 reference statements)

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“…In a finite one, on the other hand, part of the leaked waves will be reflected back to the interface and contribute more to the SLG absorption. The dominant effect in photoresponse, however, remains in the Au/air SPP, as inferred by the Fourier amplitudes in Figs.3b-e, and confirmed by the absorp- Besides photodetection, SPP+incident wave interference in a MGM architecture also lends itself to labelfree surface plasmon biosensing [68][69][70][71], whereby SLG assumes the role of an integrated transducer providing direct electrical readout, thus eliminating the need for optical measurements. The use of SLG as an integrated transducer was reported in a dielectric waveguide sensor geometry [72], but not in surface plasmon sensing.…”

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confidence: 57%

Surface Plasmon Polariton Graphene Photodetectors

et al. 2015

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The combination of plasmonic nanoparticles and graphene enhances the responsivity and spectral selectivity of graphene-based photodetectors. However, the small area of the metal-graphene junction, where the induced electron-hole pairs separate, limits the photoactive region to sub-micron length scales. Here, we couple graphene with a plasmonic grating and exploit the resulting surface plasmon polaritons to deliver the collected photons to the junction region of a metal-graphenemetal photodetector. This results into a 400% enhancement of responsivity and a 1000% increase in photoactive length, combined with tunable spectral selectivity. The interference between surface plasmon polaritons and the incident wave introduces new functionalities, such as light flux attraction or repulsion from the contact edges, enabling the tailored design of the photodetector's spectral response. This architecture can also be used for surface plasmon bio-sensing with direct-electricreadout, eliminating the need of complicated optics.Graphene-based photodetectors (PDs) [1,2] have been reported with ultra-fast operating speeds (up to 262GHz from the measured intrinsic response time of graphene carriers [3]) and broadband operation from the visible and infrared [3][4][5][6][7][8][9][10][11][12][13][14][15][16] up to the THz [17][18][19]. The simplest graphene-based photodetection scheme relies on the metal-graphene-metal (MGM) architecture [5,7,8,11,[20][21][22], where the photoresponse is due to a combination of photo-thermoelectric and photovoltaic effects [5,7,8,11,[20][21][22]. For both mechanisms, the presence of a junction is required to spatially separate excited electronhole (e-h) pairs [5,7,8,11,[20][21][22]. At the metal-graphene junction, a work-function difference causes charge transfer and a shift of the graphene Fermi level underneath the contact [4,5,7,23], compared to that of graphene away from the contact [4,5,7,23], resulting into a build-up of an internal electric field (photovoltaic mechanism) [5,7,24,25] and into a difference of Seebeck coefficients (photo-thermoelectric mechanism) [11,21,26]. An alternative way to create a junction is to use a set of gate electrodes to electrostatically dope graphene [8,11].

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confidence: 57%

Surface Plasmon Polariton Graphene Photodetectors

et al. 2015

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“…The propagation constant exhibits roughly a linear dependence on the refractive index with a slope 1 1 23.76 rad m RIU s − − = ⋅µ ⋅ around 830 nm (RIU, refractive index unit). The slope increases with decreasing the wire cross section and represents the sensitivity to the index change which may find applications in plasmonic sensing [39]. We will later exploit such dependence of wavevector on the refractive index to control the emission of a nanoantenna.…”

Section: Waveguiding On a Single Nanowirementioning

confidence: 99%

Plasmonic mode converter for controlling optical impedance and nanoscale light-matter interaction

Hung

Huang

2012

Opt. Express

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Abstract:To enable multiple functions of plasmonic nanocircuits, it is of key importance to control the propagation properties and the modal distribution of the guided optical modes such that their impedance matches to that of nearby quantum systems and desired light-matter interaction can be achieved. Here, we present efficient mode converters for manipulating guided modes on a plasmonic two-wire transmission line. The mode conversion is achieved through varying the path length, wire cross section and the surrounding index of refraction. Instead of pure optical interference, strong near-field coupling of surface plasmons results in great momentum splitting and modal profile variation. We theoretically demonstrate control over nanoantenna radiation and discuss the possibility to enhance nanoscale light-matter interaction. The proposed converter may find applications in surface plasmon amplification, index sensing and enhanced nanoscale spectroscopy.

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“…However, their sensing capability is generally limited by the relatively low sensitivity, broad spectral linewidth and weak resonance intensity [10][11]. The reported refractive index (RI) sensitivities (detection limits) for these nanoplasmonic sensors are one to two orders of magnitude lower (larger) than those of typical prism-based sensing systems [12][13]. Another widely used nanoplasmonic sensing technique is SPP interferometry, which uses the phase-sensitive interference to control the linewidth of the interference pattern, which may improve the sensing resolution [14][15][16].…”

Section: Introductionmentioning

confidence: 99%