All‐Optical Control of Microfiber Knot Resonator Based on 2D Ti₂CT_x MXene

Abstract

All-optical devices have become a research hotspot with the development of all-optical networks. [1,2] In recent years, a large number of all-optical devices based on 2D materials have been intensively investigated, [3][4][5][6][7][8][9] such as saturated absorbers (SAs), all-optical thresholders, optical Kerr switches, wavelength convertersand modulators. In 2015, an all-fiber all-optical modulator via the thermo-optic effect of graphene-deposited microfiber was demonstrated, [10] which set off a new wave of research in all-optical modulators based on the photothermal effect of 2D materials. After that, tungsten disulfide (WS 2 ), [11] black phosphorus, [12] MXene, [13,14] bismuthene, [15] and antimonene [16] have also been employed to devise all-optical modulators on platforms of Mach-Zehnder interferometer (MZI) and Michelson interferometer (MI). However, both MZI and MI structures are very sensitive to ambient temperature and stress perturbations, leading to poor environmental stability. [17,18] Additionally, the response time of the all-optical modulators based on the photothermal effect of 2D materials is several milliseconds, severely limiting their practical applications. Therefore, it is of great importance to improve the response speed and environmental stability of the all-fiber all-optical modulators.Theoretically and experimentally, decreasing the diameter of microfiber and choosing proper 2D materials with high thermal conductivity and high photothermal conversion efficiency can effectively improve the modulation rate by accelerating the heat generation and dissipation processes. In recent years, microfiber knot resonator (MKR), fabricated by knotting a microfiber into a ring, has attracted great attentions for its potential applications in filters, optical buffers, routers and logic gates. [1] The microfiber diameter of MKR is as small as a few micrometers and even sub-micrometers, [19,20] significantly thinner than those in MZI-and MI-based modulators, suggesting that MKR can be able to realize a faster response behavior. In addition, the small microfiber diameter guarantees sufficient interactions between the strong evanescent field of MKR and other materials, implying that MKR can be easily devised as various all-optical devices. [21] Moreover, it was reported that the ring diameter of MKR is only ≈0.3-1 mm, [20,[22][23][24][25] endowing MKR with many advantages such as compact size and good antiinterference. On the other hand, as a new promising 2D material, MXene is verified to possess high thermal conductivity [26] All-optical devices based on 2D materials have attracted great attention for desirable applications, such as communications and signal processing. However, the previously reported all-fiber all-optical devices utilizing the interferometer structures greatly limit their practical applications due to the poor anti-interference ability and slow modulation rate. In this work, an all-optical device has been demonstrated based on a microfiber knot resonator (MKR) deposited with Ti 2 CT x...

2D Transition Metal Carbides (MXenes) for Third Order Nonlinear Optics: Status and Prospects

“…These fascinating NLO refractionassociated characteristics lead to a plethora of exciting applications, such as optical diodes, [117] and optical modulators. [118] Proper NLO refraction properties of materials can be extracted by multiple measure techniques, such as degenerate four-wave mixing, [119] spatial self-phase modulation (SSPM), [120] nonlinear interference technique [121] and close-aperture Z-scan, [99] etc. Owing to the high sensitivity and convenience, close-aperture Z-scan and SSPM have become two of the most popular technologies for characterizing NLO refraction parameters of NLO material.…”

“…[2a,143] Because of their novel electrical and optical properties, 2D layered materials open up a new phase for photonics devices application that are fundamentally different from previous bulk devices. The newly developed 2D MXenes were instrumental in achieving a variety of exciting NLO applications, such as alloptical modulation, [118,125,144] saturable absorber, [104,105,109,145] passive photonic diodes, [101] and white laser. [9,65] The unique surface groups and variety of elemental components of MXenes provide additional dimensions for designing and modulating the performance of MXene-based nanophotonic devices.…”

Highly Sensitive Photothermal Fiber Sensor Based on MXene Device and Vernier Effect

“…The transmission spectra of the MKR s are shown in Figure 3 d–f. The free spectral ranges ( FSRs ) corresponding to MKR _1 and MKR _2 were 0.585 and 0.505 nm, respectively, according to the formula FSR = λ 2 /(π D · n ef f ), where λ is an incident wavelength, D is the diameter of the MKR , and n eff is an effective refractive index [ 31 ]. The calculated FSRs of MKR _1 and MKR _2 were 0.586 and 0.502 nm, respectively, which is consistent with our experimental results.…”

Thermal Properties of MXenes and Relevant Applications

“…Triggers/Drivers Ion transport p [170][171][172]206] Actuators p p p p [173][174]207] Motion of liquid droplets p [208] Self-healing polymerization p [209] Responsive hydrogels p [210] Thermoacoustic devices p [91] All optical modulation devices p p [128,211] Modulators for neuronal electrical activity p [212] Heat management Heaters p p [213] Heat dissipation p p [176][177] Heat insulation p p [178][179] Structure patterning at high temperatures p p [214] Multispectral camouflage devices p p [86,215] reactivity at elevated temperatures up to 2000 °C as well as the temperature-dependent properties) and thermophysical properties (i.e., heat conduction capability, coefficient of thermal expansion, thermoelectric properties, Joule heating and photothermal conversion effect). Though MXenes have shown great potential to be applied in a range of fields based on the unique thermal properties (including biological agents, environmental protection, energy conversion/storage devices, sensors/detectors, triggers for chemical reactions or physical changes, and heat management strategies), this research area is still in its infancy.…”