Reversible all-optical control of optical microcavities by a self-assembled azobenzene monolayer

Jinghan He; Andre Kovach; Dongyu Chen; Raymond Yu; Andrea M. Armani

doi:10.1117/12.2578010

5 March 2021 Reversible all-optical control of optical microcavities by a self-assembled azobenzene monolayer

Jinghan He, Andre Kovach, Dongyu Chen, Raymond Yu, Andrea M. Armani

Proceedings Volume 11683, Organic Photonic Materials and Devices XXIII; 116830A (2021) https://doi.org/10.1117/12.2578010
Event: SPIE OPTO, 2021, Online Only

Abstract

Azobenzene is capable of reversibly switching its conformation upon the UV/Visible optical exposure due to its reversible trans/cis photoisomerization. By merging this organic material with conventional photonic devices, new architectures can be developed. In our study, we developed hybrid organic/inorganic whispering gallery mode microcavities consisting of a self-assembled 4-(4-diethylaminophenylazo)pyridine (Aazo) monolayer anchored on an integrated SiO₂ optical microtoroid. As the Aazo monolayer changed conformations, the resonant wavelength was tuned. The surface density of Aazo was modified by introducing CH₃ spacer molecules providing control over the magnitude of the shift. Owing to the uniformity of Aazo monolayer, cavity quality factors reached above 1 million in the near-IR range. Two optical lasers were simultaneously coupled into the Aazo-coated devices with a single waveguide. The 1300 nm laser is used to excite and monitor a single resonant wavelength of the cavity, and the 410 nm laser triggers the thermodynamically stable trans-Aazo to photoswitch to the thermodynamically unfavored cis-Aazo. When the Aazo photoswitches, the cavity resonant wavelength at near-IR wavelength shifts due to a change of refractive index in the Aazo layer. To revert the molecule back to trans-Aazo, a CO₂ laser is used to heat the device system. Even after storage in air, the switching behavior is unchanged. Theoretical analyses are conducted based on density functional theory of the Aazo isomers combined with finite element method simulations of the optical mode. The theoretical results agree with the experimental findings.

Conference Presentation

Citation Download Citation

Jinghan He, Andre Kovach, Dongyu Chen, Raymond Yu, and Andrea M. Armani "Reversible all-optical control of optical microcavities by a self-assembled azobenzene monolayer", Proc. SPIE 11683, Organic Photonic Materials and Devices XXIII, 116830A (5 March 2021); https://doi.org/10.1117/12.2578010

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