We describe theoretically a new long-wave infrared optical modulator based on the characteristics of TM surface plasmons in graphene. Calculations made using a finite-τ random phase approximation model, of relevant surface
plasmon propagation parameters, are presented. We show that the plasmon losses vary as a function of carrier density; for large carrier densities, interband absorption of the plasmon energy is blocked due to filling of the conduction band states, and for small carrier densities, the plasmon energy is absorbed


Graphene monolayers have recently been used as saturable absorbers for modelocking ultrafast fiber lasers [11, 12]. In this work, the saturable absorption also occurs as a result of the state blocking mechansim. Although a significant modification of our physical picture through the addition of phonon scattering and possibly other mechanisms would be required to model this wavelength range appropriately, it may be possible to extend the modulator discussed here to shorter (telecommunication) wavelengths.





11. Q. Bao, H. Zhang, Y. Wang, Z. Ni, Y. Yan, Z. X. Shen, K. P. Loh, and D. Y. Tang,
“Atomic-layer graphene as a saturable absorber for ultrafast pulsed lasers,” Adv. Functional
Materials 19, 3077–3083 (2009).
12. H. Zhang, D. Y. Tang, L. M. Zhao, Q. L. Bao, and K. P. Loh, “Large energy mode
locking of an erbium-doped fiber laser with atomic layer graphene,” Optics Express 17, 17630–17635 (2009).