Boron Nanosheets for Efficient All‐Optical Modulation and Logic Operation

Abstract

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...

Fiber all-optical light control with low-dimensional materials (LDMs): thermo-optic effect and saturable absorption

“…The work with boron obtained a relatively fast rising time constant of 0.48 ms due to the superior photo-thermal response. 20 The work with graphene shows 0.51p phase shi at a low pump power of 5.3 mW due to the long interaction length of LDM graphene. 18 For MI structures with LDMs, three studies have been performed with antimonene, bismuthene and MXene respectively.…”

“…The system structures of these ber alloptical devices can be generally classied into 2 main categories: non-resonant and resonant designs. For non-resonant designs, three typical designs will be discussed: they are Mach-Zehnder interferometer (MZI), 14,16,[18][19][20] Michelson interferometer (MI), 11,12,67 and polarization interferometer (PI). 13 For resonant design, micro-rings 95 will be discussed.…”

“…[4][5][6][7] Fiber all-optical light control utilizes mature ber technologies and allows alloptical devices to be compatible with current ber communication systems. Therefore, ber all-optical light control has attracted widespread research interests and many of the latest results have reported all-optical modulators, [8][9][10][11][12][13][14][15][16][17] phase shiers, 12,14,[17][18][19] logic gates, 12,14,20 and switches. 2,[5][6][7]15,18,19,[21][22][23] Meanwhile, LDMs have been a research hotspot because of their plentiful photonic and optoelectronic properties including graphene, 9,[24][25][26][27] graphene oxide, 28,29 carbon nanotubes (CNTs), [30][31][32] transition metal dichalcogenides (TMDs), [33][34][35] topological insulators (TIs), [36]…”

“…Many all-optical devices based on these two effects have been reported. [11][12][13][14]16,[18][19][20]62,[65][66][67][68] Therefore, it is very important to build up a complete view on the principle and performance of these devices.…”

Recent progress on applications of 2D material-decorated microfiber photonic devices in pulse shaping and all-optical signal processing

“…All-optical phase shifters and switches play an important role for various all-optical applications including all-optical signal processing, sensing, and communication. It has been demonstrated that with 2D material-decorated microfiber photonic devices, the phase shifters and optical switches could be realized [277][278][279][280][281][282]. In 2015, Gan et al demonstrated an all-fiber phase shifter by employing graphene's optical absorption and excellent thermal properties [277].…”