A Solution‐Processed Ultrafast Optical Switch Based on a Nanostructured Epsilon‐Near‐Zero Medium

Guo, Qiangbing; Cui, Yudong; Yao, Yunhua; Ye, Yuting; Yue, Yang; Liu, Xueming; Zhang, Shian; Liu, Xiaofeng; Qiu, Jianrong; Hosono, Hideo

doi:10.1002/adma.201700754

Cited by 120 publications

(93 citation statements)

References 46 publications

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“…As for optical modulation, an indispensable technology for modern optical communication, controlling optical properties of a material by changing its refractive index is a widely adopted pathway . The refractive index of a material, however, is temperature dependent, which implies a way for optical modulation mediated by thermal control.…”

Section: Comparison Of Different 2d Materials‐based Similar Devicesmentioning

confidence: 99%

Boron Nanosheets for Efficient All‐Optical Modulation and Logic Operation

Guo

Shao

et al. 2019

Advanced Optical Materials

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As the left neighbor of carbon in the periodic table, boron is very similar to carbon in electronic properties and strong bonding characters, and both undertake important roles in living organisms. [8][9][10][11] However, due to the unique trivalent electronic configuration, boron is among the most chemically versatile elements, which shows polymorphism in low-dimensional structures and thus richer properties, such as high-temperature superconductivity, high carrier mobility, massless Dirac fermions, superhardness, to name a few. [12][13][14][15][16][17][18][19][20][21] Although the 2D form borophene has recently been experimentally realized by several groups under ultrahigh-vacuum conditions and by another one with chemical vapor deposition (CVD), [12,15,22,23] the related researches of borophene are still mainly concentrated on theoretical predictions and computational calculations. [13,20,21,[24][25][26][27][28] Experimental work is largely lagged behind, which, to a large extent, is due to its chemical and structural complexities and thus challenging synthesis. [13,14] On the other hand, up to now, most of 2D boron-related researches are on the electronic and mechanical properties by theoretical methods, let alone experimental study of its optical properties and related applications. According to several recent theoretical predictions, 2D boron bears fascinating features that are totally different from other 2D materials, such as thicknessdependent transparency and visible/near-infrared plasmons. [26,27] Here, based on liquid-exfoliated boron nanosheets, for the first time, we demonstrate an all-optical phase shifter at the telecommunication band that is mediated by the efficient photo-thermal response in boron nanosheets. The constructed phase shifter shows an order of magnitude faster response speed and higher modulation efficiency compared with other 2D material-based similar devices. Consequently, a high-efficiency and stable allfiber, all-optical modulator was successfully realized based on a Mach-Zehnder interferometer (MZI) configuration, which could be further employed for all-optical logic gating operations. As proof-of-concept demonstrations, we successfully achieved all-optical logic AND and NOT gates by exploiting the superior photo-thermal response in boron nanosheets. Our work marks an important step toward exploring the optical and photonic applications of 2D boron nanosheets.Due to its unique trivalent electronic configuration, boron features richer properties as well as higher chemical and structural complexities compared with its right neighbor carbon. Consequently, over a decade later than the exfoliation of graphene, borophene has just been experimentally demonstrated on certain metal substrates and under ultrahigh-vacuum conditions, which, however, limit its wide and in-depth experimental researches. Here, for the first time, by employing liquid-exfoliated boron nanosheets, all-optical signal processing application is explored based on its superior photo-thermal response. A stable all-opt...

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Section: Comparison Of Different 2d Materials‐based Similar Devicesmentioning

confidence: 99%

Boron Nanosheets for Efficient All‐Optical Modulation and Logic Operation

Guo

Shao

et al. 2019

Advanced Optical Materials

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“…However, their applications in integrating optics devices have always been hampered by the high optical losses due to interband transitions, large real component of their dielectric constant, and fixed carrier density . In the past few years, the search of low‐loss and widely tunable plasmonic media has led to the development of diverse nonmetallic plasmonic nanocrystals, such as copper chalcogenides, transparent conducting oxides, and oxygen‐deficient metal oxides . These nonmetallic plasmonic materials exhibit enormous advantages in device performance, design flexibility, and property tunability.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast Nonlinear Optical Response in Plasmonic 2D Molybdenum Oxide Nanosheets for Mode‐Locked Pulse Generation

Wang

Yue

Liu

et al. 2018

Advanced Optical Materials

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2D plasmons are of particular interest in the exploration of light–matter interactions in 2D materials. In 2D plasmonic materials, response time (in sub‐picosecond scale) of free carriers is order of magnitude faster than excitonic recombination in semiconductors, making them highly attractive for realizing faster optical switching and modulation in nanoscale devices. However, the small carrier density in gapless 2D plasmonic materials like graphene has strongly limited the strength of light–matter interaction and the operative spectral range. Here, it is shown that in optically activated plasmonic molybdenum oxide (MoO3) sheets of atomic thickness, the nonlinear optical (NLO) absorption, characterized by a saturable behavior in the near‐infrared region, is notably enhanced by the plasmon resonance, giving a modulation depth of 34.96%. Ultrafast pump‐probe spectroscopy reveals that the transient photobleaching in plasmonic MoO3 nanosheets associated with the relaxation of hot electrons recovers in a timescale less than 200 femtoseconds (fs). This ultrafast NLO response allows the development of an optical switch based on saturable absorption that enables the generation of mode‐locked laser pulses from a fiber laser operating at 1.0 µm region. The results may have strong implications for the application of 2D plasmonics based on 2D MoO3 in nanophotonics.

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“…With pump‐probe experiments, we demonstrate broadband optically induced switching of unpatterned films in the transmission mode and the reflection mode, with a maximum reflectance change of 135% in the MIR region with a relaxation time of 45.6 ps for a pump fluence of 1.3 mJ cm −2 . This change in the reflectance with respect to pump power is significantly higher than previous demonstrations of optical modulation in switching platforms such as ENZ AZO films (40% for 4 mJ cm −2 ), ITO nanocrystals (150% at 18.16 mJ cm −2 ), and even patterned metasurfaces (35% for 0.40 mJ cm −2 ) . We identify the possible carrier relaxation mechanisms for photoexcited carriers in CdO and show that the relaxation time decreases with increasing doping levels.…”

Section: Introductionmentioning

confidence: 62%

Broadband, High‐Speed, and Large‐Amplitude Dynamic Optical Switching with Yttrium‐Doped Cadmium Oxide

Saha

Diroll

Shank

et al. 2019

Adv Funct Materials

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Transparent conducting oxides, such as doped indium oxide, zinc oxide, and cadmium oxide (CdO), have recently attracted attention as tailorable materials for applications in nanophotonic and plasmonic devices such as low‐loss modulators and all‐optical switches due to their tunable optical properties, fast optical response, and low losses. In this work, optically induced extraordinarily large reflection changes (up to 135%) are demonstrated in bulk CdO films in the mid‐infrared wavelength range close to the epsilon near zero (ENZ) point. To develop a better understanding of how doping level affects the static and dynamic optical properties of CdO, the evolution of the optical properties with yttrium (Y) doping is investigated. An increase in the metallicity and a blueshift of the ENZ point with increasing Y‐concentrations is observed. Broadband all‐optical switching from near‐infrared to mid‐infrared wavelengths is demonstrated. The major photoexcited carrier relaxation mechanisms in CdO are identified and it is shown that the relaxation times can be significantly reduced by increasing the dopant concentration in the film. This work could pave the way to practical dynamic and passive optical and plasmonic devices with doped CdO spanning wavelengths from the ultraviolet to the mid‐infrared region.

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A Solution‐Processed Ultrafast Optical Switch Based on a Nanostructured Epsilon‐Near‐Zero Medium

Cited by 120 publications

References 46 publications

Boron Nanosheets for Efficient All‐Optical Modulation and Logic Operation

Boron Nanosheets for Efficient All‐Optical Modulation and Logic Operation

Ultrafast Nonlinear Optical Response in Plasmonic 2D Molybdenum Oxide Nanosheets for Mode‐Locked Pulse Generation

Broadband, High‐Speed, and Large‐Amplitude Dynamic Optical Switching with Yttrium‐Doped Cadmium Oxide

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