Plasmons in highly doped graphene offer the means to dramatically enhance light absorption in the atomically thin material. Ultimately the absorbed light energy induces an increase in electron temperature, accompanied by large shifts in the chemical potential. This intrinsically incoherent effect leads to strong intensity-dependent modifications of the optical response, complementing the remarkable coherent nonlinearities arising in graphene due to interband transitions and anharmonic intraband electron motion. Through rigorous time-domain quantum-mechanical simulations of graphene nanoribbons, we show that the incoherent mechanism dominates over the coherent response for the high levels of intensity required to trigger nonperturbative optical phenomena such as saturable absorption. We anticipate that these findings will elucidate the role of coherent and incoherent nonlinearities for future studies and applications of plasmon-assisted nonlinear optics.

中文翻译：

---

纳米结构石墨烯中的瞬态非线性等离子体

高掺杂石墨烯中的等离激元提供了显着增强原子薄材料中光吸收的方法。最终，吸收的光能引起电子温度的升高，并伴随着化学势的大幅度变化。这种内在的非相干效应导致了光响应的强依赖强度的修正，从而补充了由于带间跃迁和非谐带内电子运动而在石墨烯中产生的显着相干非线性。通过对石墨烯纳米带的严格时域量子力学模拟，我们表明，对于触发非扰动光学现象（如饱和吸收）所需的高强度强度，非相干机制在相干响应中占主导地位。