THz modulation of monolayer WSe2-silicon hybrid structure and its performance after oxidation

Zhaoji Fang; Chenyi Xia; Zheng Li; Bo Wang; Yuan Huang; Li Wang; Xiaojun Wu

doi:10.1117/12.2502255

9 November 2018 THz modulation of monolayer WSe₂-silicon hybrid structure and its performance after oxidation

Zhaoji Fang, Chenyi Xia, Zheng Li, Bo Wang, Yuan Huang, Li Wang, Xiaojun Wu

Proceedings Volume 10826, Infrared, Millimeter-Wave, and Terahertz Technologies V; 108261L (2018) https://doi.org/10.1117/12.2502255
Event: SPIE/COS Photonics Asia, 2018, Beijing, China

Abstract

In recent years, THz modulators have been improved by 2D materials, yet facing a conflict between the demand for high modulation depth and the limitation of low pump power. Previously, by pumping continuous-wave laser on a highresistivity silicon wafer, we achieved modulation depth >95% in 0.3-1.5 THz, demanding continuous-wave pump power of 11.8 W. In this work, we added a mono-layer WSe₂ on the high-resistivity silicon wafer by mechanical exfoliation, raising the modulation depth of THz pulse from 20% to 58% under 0.05 W femtosecond laser pump. The modulation depth can be further enhanced by raising pump power. The modulation behavior is most significant from 1.3 THz to >1.5 THz. This modulation enhancement is due to the interface state between WSe₂ and silicon, as well as the direct bandgap of mono-layer WSe₂. If exposed to the air, WSe₂ starts oxidization at a low exciting power of <1 mW. Experiments shows that even if WSe2 is partly oxidized to WO₃, the modulation depth is only slightly weakened, yet still better than the bare silicon substrate. Also, even if WSe₂ does not fully cover the range of THz wave, or if the pump laser beam does not fully cover the range of THz wave, the modulation enhancement is also partly effective. Our work suggests a lowcost way to improve the efficiency of all-optical THz modulators.

Citation Download Citation

Zhaoji Fang, Chenyi Xia, Zheng Li, Bo Wang, Yuan Huang, Li Wang, and Xiaojun Wu "THz modulation of monolayer WSe₂-silicon hybrid structure and its performance after oxidation", Proc. SPIE 10826, Infrared, Millimeter-Wave, and Terahertz Technologies V, 108261L (9 November 2018); https://doi.org/10.1117/12.2502255

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available