Electronic origin of spatial self-phase modulation: Evidenced by comparing graphite with C60 and graphene

Abstract

We report unambiguous observation of spatial self-phase modulation (SSPM) in a dispersive suspension of graphite flakes. This coherent nonlinear optical effect in bulk graphite is found to be broadband and large, with a third-order nonlinear susceptibility χ(3) of 2.2 × 10−9 esu (i.e., 3.1 × 10−17 m2/V2 in SI units) at 532 nm excitation. Comparison with other carbon allotropes shows that this value is 5 × 107 times higher than that of C60 but ∼50 times lower than that of graphene, fully exhibiting the electronic origin of SSPM.

Nonlinear optical response spatial self-phase modulation in MoTe2: correlations between χ(3) and mobility or effective mass

“…The third-order nonlinear optical coefficients χ (3) of quantum materials can be measured by only a few experimental methods, including spatial self-phase modulation (SSPM) [5][6][7][8][9][10][11], third-harmonic generation (THG) [12,13], Z-scan [14], and four-wave mixing (FWM) [15]. SSPM is a third-order nonlinear optical effect [5] found previously in liquid crystal, dye solution [8] and dispersions of 2D materials [5], where the refractive index n of the medium is linearly dependent on the laser intensity I as n = n 0 + n 2 × I.…”

“…Compared with other coherent methods like THG and FWM, the third-order optical qualities in SSPM are strong and have excellent contrast ratio, making SSPM an effective tool to characterize the third order nonlinear optical property of materials. Recently SSPM effects in a few 2D material dispersions have been investigated, including graphene [6], MoS 2 [5], MoSe 2 [7], black phosphorous [10], Bi 2 Se 3 [16] and graphite [11]. In the recent investigation of SSPM for MoS 2 , it was discovered the SSPM effect is closely related to the confined behavior of 2D electrons [5].…”

Recent Advances in Spatial Self‐Phase Modulation with 2D Materials and its Applications

“…Subsequently, they continued investigations to confirm their views. [42,220] Wu et al found that the mobility of carriers (C 60 and graphene) has a significant influence on 3 , which seems to prove the origin of electrons. Recently, Zhao's team found that the effective mass of electrons and the carrier mobility depend on 3 strictly by summarizing some of SSPM's work (Figure 6f,g).…”

“…Subsequently, this band gap-dependent SSPM was also observed in MoSe 2 [42] and graphite. [220] Recently, numerous studies on the SSPM effect of 2D materials have considered the photonic band gap. [34,50,164,177] In contrast, the band gap of a large number of 2D materials changes with the number of layers.…”

Near-Infrared Spatial Self-Phase Modulation in Ultrathin Niobium Carbide Nanosheets

“…Owing to their fascinating non-linear photonics applications [3,4], tremendous efforts have been made to explore the non-linear optical properties of 2D materials including graphene [5,6], transition metal chalcogenides (TMDCs) [7], black phosphorus [8][9][10], and MXenes [11,12]. Previous studies report on SSPM in various 2D materials such as graphene [13], MoS 2 [14,15], MoTe 2 [16], tellurium [17], NbSe 2 [18], and so on [19][20][21][22][23][24][25][26]. Over the past years, large-scale production of 2D materials has enabled their application in all-optical switches, all-optical modulators, and passive photonic diodes [27].…”