Electrically Tunable Four-Wave-Mixing in Graphene Heterogeneous Fiber for Individual Gas Molecule Detection

Abstract

Detection of individual molecules is the ultimate goal of any chemical sensor. In the case of gas detection, such resolution has been achieved in advanced nanoscale electronic solid-state sensors, but it has not been possible so far in integrated photonic devices, where the weak light-molecule interaction is typically hidden by noise. Here, we demonstrate a scheme to generate ultrasensitive down-conversion four-wave-mixing (FWM) in a graphene bipolar-junction-transistor heterogeneous D-shaped fiber. In the communication band, the FWM conversion efficiency can change steeply when the graphene Fermi level approaches 0.4 eV. In this condition, we exploit our unique two-step optoelectronic heterodyne detection scheme, and we achieve real-time individual gas molecule detection in vacuum. Such combination of graphene strong nonlinearities, electrical tunability, and all-fiber integration paves the way toward the design of versatile high-performance graphene photonic devices.

Stokes dual-soliton spectroscopy in a graphene functionalized over-modal microresonator

“…Moreover, when the GMDC is exposed to NH 3 , the large steps are rare (such as > 2 molecular on/off events), whereas unit steps are dominant. These statistical results obey a power-law distribution, which is also a sign of individual molecule adsorption events [10].…”

Graphene-Fiber Biochemical Sensors: Principles, Implementations, and Advances

“…Graphene has rich nonlinear phenomena including the saturable absorption, second-order nonlinearity, and third-order nonlinearity [13]. The contact between the external molecule and graphene will cause changes in nonlinear parameters of graphene, thereby affecting the intensity or efficiency of graphene nonlinear signals such as four-wave-mixing (FWM) and stimulated Brillouin scattering (SBS) [20,21]. For instance, Fig.…”

“…Exploiting this feature, there is a relationship between the FWM efficiency and the adsorption of gas molecules, because the polar gas molecules could change the Fermi level of graphene. When graphene is predoped around 0.4 eV, the sensor achieves the highest sensitivity [21].…”

“…In addition to optimizing fiber structure and materials to improve the performance, some new sensing mechanisms are introduced in recent years [20,21]. Typically, Yao et al [20] proposed a microfiber interrogated whispering gallery mode (WGM) optomechanical gas sensor, which expanded "electron-photon" interaction in conventional graphene based optical sensors to "electron-phonon-photon" interaction.…”

“…Among the graphene based photonic devices, the biochemical sensor is one of the most rapidly developed applications. Via continuously optimizing the graphene materials, the fiber structures, and their combinations, the performance of graphene-fiber biochemical sensors is pushed to new height constantly, such as ultrahigh sensitivity [20,21] and selectivity [5]. Fig.…”