Linear and Nonlinear Optical Absorption of on-chip Silicon-on-insulator Nanowires with Graphene

Yu, Longhai; Xu, Yang; Shi, Yaocheng; Dai, Daoxin

doi:10.1364/acpc.2012.as1b.3

Cited by 5 publications

(5 citation statements)

References 10 publications

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“…In contrast, the carriers generated in the silicon layer would introduce some free carrier absorption (FCA) loss depending on the free carrier concentration. 28,29 For the present case, there is no FCA loss observed for the probe light propagating along the SOI nanowire without graphene when the pump light is "ON" with a power of 15 mW, indicating that the FCA loss in the silicon layer is negligible (which is consistent with the theoretical estimation) because the carrier concentration is low here. Since we have observed loss reduction (instead of loss increase) in the experiment as shown in Figure 2b, the OIT effect should not directly come from the variation of carrier concentration in the ARTICLE silicon layer.…”

Section: Resultssupporting

confidence: 88%

“…A new ultrathin (∼1 Å) SiO 2 layer might be formed quickly afterward because of exposure in air. A large-size (about 1 cm × 1 cm) graphene sheet grown by chemical vapor deposition (CVD) is then wet-transferred onto the SOI chip, , without requiring any precise alignment. A dry-etching process with oxygen plasma is then applied to remove the graphene covering the regions including the 10 μm-wide grating couplers as well as their 200 μm-long adiabatic tapers.…”

Section: Methodsmentioning

confidence: 99%

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Local and Nonlocal Optically Induced Transparency Effects in Graphene–Silicon Hybrid Nanophotonic Integrated Circuits

Zheng

et al. 2014

ACS Nano

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Graphene is well-known as a two-dimensional sheet of carbon atoms arrayed in a honeycomb structure. It has some unique and fascinating properties, which are useful for realizing many optoelectronic devices and applications, including transistors, photodetectors, solar cells, and modulators. To enhance light-graphene interactions and take advantage of its properties, a promising approach is to combine a graphene sheet with optical waveguides, such as silicon nanophotonic wires considered in this paper. Here we report local and nonlocal optically induced transparency (OIT) effects in graphene-silicon hybrid nanophotonic integrated circuits. A low-power, continuous-wave laser is used as the pump light, and the power required for producing the OIT effect is as low as ∼0.1 mW. The corresponding power density is several orders lower than that needed for the previously reported saturated absorption effect in graphene, which implies a mechanism involving light absorption by the silicon and photocarrier transport through the silicon-graphene junction. The present OIT effect enables low power, all-optical, broadband control and sensing, modulation and switching locally and nonlocally.

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Section: Resultssupporting

confidence: 88%

Section: Methodsmentioning

confidence: 99%

Local and Nonlocal Optically Induced Transparency Effects in Graphene–Silicon Hybrid Nanophotonic Integrated Circuits

Zheng

et al. 2014

ACS Nano

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“…3(b), including the resonant wavelengths of the SC-ADSMR before and after graphene transfer, the corresponding extinction ratio and the FWHM of the transmission spectra. Utilizing the analytical method, the LAC of the GSHW in our case has a mean value of 0.23 dB/µm, which is comparable to the results in literature [23,24].…”

Section: Fig 4 Scheme Of Thesc-adsmr With Patternedmonolayer Graphenesupporting

confidence: 87%

“…Broadband optical modulator [17,18], mode locked laser [19], broadband photodetectors [20,21], and enhanced parametric frequency conversion [22] have all been demonstrated utilizing graphene-silicon hybrid waveguides (GSHWs). Owing to its intrinsic physical properties, the linear absorption coefficients (LACs) of GSHWs range from 0.04dB/µm to 0.33 dB/µm [23,24],which are much larger than those of silicon waveguides [25]. The LACs of GSHWs are dependent on the quality of the transferred graphene and the waveguide configurations [26], thus are required to be optimized for practical applications.…”

mentioning

confidence: 99%

Enhanced linear absorption coefficient of in-plane monolayer graphene on a silicon microring resonator

Cai¹,

Cheng²,

Zhang³

et al. 2016

Opt. Express

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Abstract:We demonstrate that linear absorption coefficient (LAC)of a graphene-silicon hybrid waveguide (GSHW) is determined by the optical transmission spectra of a graphene coated symmetrically coupled add-drop silicon microring resonator (SC-ADSMR), of which the value is around 0.23 dB/µm. In contrast to the traditional cut-back method, the measured results aren't dependent on the coupling efficiency of the fiber tip and the waveguide. Moreover, precision evaluation of graphene coated silicon microring resonator (SMR) is crucial for the optoelectronic devices targeting for compact footprint and low power consumption.Graphene is a two-dimensional material [1][2][3], which exhibits remarkable optoelectronic characteristics, such as ultrahigh carrier mobility at room temperature [4,5], ultra-broadband absorption [6,7], controllable band-gap transition [8], and giant Kerr coefficient [9,10]. Graphene has been integrated on photonic integrated circuits (PICs) in which the hexagonal carbon sheet is evanescently coupled to the waveguide, leading to unprecedented optical performances [11][12][13][14][15][16].Recently, grapheme resting on silicon-on-insulator (SOI) platform offers great potential for optoelectronic devices. Broadband optical modulator [17,18], mode locked laser [19], broadband photodetectors [20,21], and enhanced parametric frequency conversion [22] have all been demonstrated utilizing graphene-silicon hybrid waveguides (GSHWs). Owing to its intrinsic physical properties, the linear absorption coefficients (LACs) of GSHWs range from 0.04dB/µm to 0.33 dB/µm [23,24],which are much larger than those of silicon waveguides [25]. The LACs of GSHWs are dependent on the quality of the transferred graphene and the waveguide configurations [26], thus are required to be optimized for practical applications. For instance, Strong LAC is preferred in electro-absorption modulator (EAM) [27] to obtain a large modulation depth, while in the nonlinear optical application [28], the LAC should be as small as possible to avoid linear absorption. Therefore, it is of great importance to precisely evaluate the optical absorption loss induced by grapheme [29].Previously, the LACs of graphene-comprising waveguides were obtained by a cut-back method [14][15][16] in which the light-graphene interaction lengths were varied. And this method is subject to the following limitations:1. In order to measure the LACs induced by graphene, multiple stripe waveguides should be patterned with different lengths of graphene [14][15][16], of which the processes are burden some, time consuming and even expensive.2. The coupling efficiencies between the fiber tips and the waveguides as well as waveguide end facets maintain non-uniformity. Moreover, such fiber-to-waveguide coupling losses are often comparable to or even much higher than the propagation losses in the waveguides [27], leading to high uncertainties in loss measurements, as stated in [30].3. Because of the imperfect coverage of grapheme with cracks, the measured losses in these stripe...

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“…A monolayer graphene sheet, grown by chemical vapor deposition (CVD) method, is wet-transferred onto the whole SOI chip without any alignment. 26,27 A third EBL process followed by an oxygen plasma etching process is then utilized to pattern the graphene sheet forming the nano-heater as well as the connecting bridges that connect the nano-heater and the metal contacts. 26 As shown in Figure 1b, the graphene nano-heater has an annulus part on the micro-disk and two straight parts extending out of the micro-disk.…”

Section: Methodsmentioning

confidence: 99%

Thermally tunable silicon photonic microdisk resonator with transparent graphene nanoheaters

Yin

Shi

et al. 2016

Optica

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137

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Thermally-tuning silicon micro-cavities are versatile and beneficial elements in low-cost large-scale photonic integrated circuits (PICs). Traditional metal heaters used for thermal tuning in silicon micro-cavities usually need a thick SiO 2 upper-cladding layer, which will introduce some disadvantages including low response speed, low heating efficiency, low achievable temperature and complicated fabrication processes. In this paper, we propose and experimentally demonstrate thermally-tuning silicon micro-disk resonators by introducing graphene transparent nano-heaters, which contacts the silicon core directly without any isolator layer. This makes the graphene transparent nano-heater potentially to have excellent performances in terms of the heating efficiency, the temporal response and the achievable temperature. It is also shown that the graphene nano-heater is convenient to be used in ultrasmall photonic integrated devices due to the single-atom thickness and excellent flexibility of graphene. Both experiments and simulations imply that the present graphene transparent nano-heater is promising for thermally-tuning nanophotonic integrated devices for e.g. optical modulating, optical filtering/switching, etc.

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Linear and Nonlinear Optical Absorption of on-chip Silicon-on-insulator Nanowires with Graphene

Cited by 5 publications

References 10 publications

Local and Nonlocal Optically Induced Transparency Effects in Graphene–Silicon Hybrid Nanophotonic Integrated Circuits

Local and Nonlocal Optically Induced Transparency Effects in Graphene–Silicon Hybrid Nanophotonic Integrated Circuits

Enhanced linear absorption coefficient of in-plane monolayer graphene on a silicon microring resonator

Thermally tunable silicon photonic microdisk resonator with transparent graphene nanoheaters

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