Antimonene-based all-optical modulator

(Nanowerk Spotlight) In recent years, all-optical modulators (AOMs) have attracted significant interests due to their low power consumption, broad bandwidth, and potential in all-optical fields. Among these, AOMs based on the high photothermal efficiency of antimonene, exhibit remarkable advantages for their large modulation depth, wide operating wavelength range, and easy implementation.
In new research, led by Professor Han Zhang at Shenzhen University in China, and published in Laser & Photonics Reviews ("An All-Optical, Actively Q-Switched Fiber Laser by an Antimonene-Based Optical Modulator"), researchers demonstrated that the antimonene-based AOM was successfully utilized to actively Q-switch a fiber laser in a fully photonics domain and this actively modulated laser represented all-optically tunable output parameters (e.g., output repetition rate), and easy time synchronization.
In this work, the antimonene nanosheets with a lateral size ranging from 35 to 120 nm and a thickness ranging from 6.7 nm to 14.5 nm, were successfully fabricated by a facile liquid phase exfoliation (LPE) approach. The prepared antimonene nanosheets suspension was dropped onto a home-made 10 µm microfiber and employed into a photothermal-based AOM as a whole. By guiding the control light into antimonene-deposited microfiber, the antimonene nanosheets absorb the control light and generate a large amount of heat due to its excellent photothermal effect.
Antimonene nanosheets can be used as an effective photothermal agent
Antimonene nanosheets can be used as an effective photothermal agent with satisfactory photothermal conversion efficacy (48%), possessing great potential in the field of all-optical, actively Q-switched fiber lasers. (Image: Dr. Yunzheng Wang, Dr. Weichun Huang, Shenzhen University)
Assisted by the large photothermal effect of antimonene, an AOM was devised with an all-fiber Michelson interferometer (MI). Thanks to the double-pass structure of MI, the maximum phase shift of 16π was achieved at the highest accessible pump power of 335 mW with a slop efficiency of 0.049π mW-1. For intensity modulation, the antimonene-based AOM possessed a rise time constant of 3.2 ms and was able to be modulated up to 2 kHz.
In addition, the conversion efficiency of phase shift of the fabricated antimonene-based AOM declines only 8.2% and both the interferometric contrast and the free spectral range have no visible change after one month, suggesting that the antimonene-based AOM has excellent long-term stability under ambient conditions, implying that it holds great practical application in the field of black phosphorus analogue nanomaterials-based AOM.
This antimonene-based AOM, for the first time, was proposed and successfully applied for the generation of Q-switched laser pulses as an all-optical active Q-switcher. Compared with conventional active Q-switcher such as bulk-crystal electro-optic modulators and acousto-optic modulators, and recently reported graphene electro-optic modulator, this antimonene-based all-optical active Q-switcher regulates the laser pulse fully in the photonics domain in the absence of external electric signals, providing a viable avenue for achieving Q-switched laser pulse with an all-optical method in the future.
It is anticipated that this actively antimonene-based all-optical modulator with advantages of high conversion efficiency, large modulation depth, low energy consumption and great long-term stability, has promising potential in all-optical information processing and pulsed laser engineering.
Provided by Shenzhen Engineering Laboratory of Phosphorene and Optoelectronics, Shenzhen University, as a Nanowerk exclusive

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