With the development of all-optical networks, all-optical devices have become a research hotspot. In recent years, a large number of all-optical devices based on two-dimensional (2D) materials have been studied, such as saturable absorbers, all-optical thresholds, optical Kerr switches, wavelength converters, and modulators.

All-optical devices based on 2D have been widely used in communication, signal processing and other fields. However, previously reported all-fiber all-optical devices using the interferometer structure have poor anti-interference ability and slow modulation rate, which greatly limits their practical applications.

In cooperation with Beijing University of Aeronautics and Astronautics and Shenzhen University, a paper entitled "All-optical control of microfiber knot resonator based on 2D Ti2CTx MXene" was published in "Advanced Optical Materials". In this work, we showed a type of deposition A 2D Ti2CTx MXene micro-nano fiber junction resonator (MKR) all-optical device is provided, which has a high light-to-heat conversion efficiency and thermal conductivity.

Experimental results show that the all-optical device has the advantages of high modulation efficiency, fast response time, good stability, and good phase and intensity modulation performance. Therefore, MKR-based all-optical devices are expected to pave the way for new designs of high-performance all-optical devices, and have great potential in future optical information processing.
All-optical modulators based on the photothermal effect of 2D materials have been successfully used to generate active Q-switched pulses in fiber lasers. The application of all-optical modulators has expanded to pulsed laser engineering.

Fig.1 Structural characteristics of the prepared Ti2CTx nanosheets
On the other hand, MXene, as a promising new 2D material, has been proven to have high thermal conductivity and high light-to-heat conversion efficiency, which is conducive to improving response time. In addition, the diversity of chemical composition (composed of more than 100 stoichiometric MXenes) and the tunable electronic strip structure show that MXene can be customized for ideal electronic and optoelectronic applications. According to reports, Ti2C has a zero-gap band structure (such as Ti2CTx <0.2 eV), which has great application potential in broadband optical devices.

Figure 2 All-optical device test characterization of MXene‘s micro-nano fiber junction resonator (MKR)
(a) Optical microscope image of MKR; (b) Experimental structure.
(c) Transmission spectra before and after MXene deposition.
(d) Transmission spectrum of all optical phase modulator for more than 7 hours.
(e) Waveforms and fitting curves of 980nm pump light (top) and output signal light (bottom).
By combining the photothermal effect of MXene and the resonance performance of MKR, phase modulation and intensity modulation are realized. Experimental results show that the all-optical modulator has the highest conversion efficiency (~ 0.196 π / mW), fast response time (microsecond rise time: 306 μs), compact structure (ring diameter is only ~ 1mm) and good environmental stability ( (No spectral change for more than 7 hours).
Therefore, we believe that our work can pave the way for the new design of high-performance all-optical devices based on 2D materials, which has huge application potential in the field of all-optical networks and signal processing.
Corresponding authors of this thesis are Associate Professor Zhang Meng and Professor Zhang Yi, and the first author is Dr. Wu Qing from Beijing University of Aeronautics and Astronautics. Together they are postdoctoral fellows of Shenzhen University Huang Weichun and Wang Yunzheng.
 
[Article link]

All-optical control of microfiber knot resonator based on 2D Ti2CTx MXene

Qing Wu, Weichun Huang, Yunzheng Wang, Cong Wang, Zheng Zheng, Hong Chen, Meng Zhang, and Han Zhang
Advanced Optical Materials, 2020-01-20

DOI: 10.1002 / adom.201900977

Source: Frontiers of 2D Materials