2D GeP as a Novel Broadband Nonlinear Optical Material for Ultrafast Photonics

Abstract

A new member of the IV–V compounds, germanium–phosphorus (Ge–P) compounds, has been shown in experiment and theory to have a tunable bandgap (Eg), excellent chemical stability, strong in‐plane anisotropy, and wide‐range optical absorption, all indicating a promising future in electronic and optoelectronic applications. In this work, the application potential of Ge–P compounds as nonlinear optical (NLO) materials in ultrafast photonics is studied for the first time. The strong light–matter interaction, broad and tunable Ep, and broadband and strong optical response make GeP a likely NLO material for photonics, especially in infrared photonic devices. In addition, 2D GeP nanosheets are mixed with poly(vinylidene fluoride) (PVDF) to obtain a GeP@PVDF composite film, which further improves the stability of the GeP and, for the development of organic photonic devices, helps to slow its degradation. From Z‐scan data and fitting results, it is found that GeP has an excellent broadband NLO response. Moreover, using the GeP@PVDF composite film as a saturable absorber, a high‐stability femtosecond laser with a 722 fs pulse width is obtained in the telecommunications band. Preliminarily, Ge–P compounds display excellent optical properties suggesting that they may be used as NLO materials in advanced photonic devices.

2D GeP-based photonic device for near-infrared and mid-infrared ultrafast photonics

“…In addition, an obvious irregular 2D structure is revealed. The HR-TEM (high resolution TEM) image illustrated in Figure 1B clearly shows the lattice fringes, and its ∼0.27 nm spacing is consistent with the characteristics of GeP [8]. The thickness of 2D GeP nanoflakes was evaluated by using atomic force microscopy (AFM), as presented in Figure 1C.…”

“…As a novel 2D material of Group IV-V compounds, 2D GeP in particular has recently attracted significant attentions of researchers in the field of optics. Interestingly, 2D GeP has appealing properties of tunable bandgap structure (0.51-1.68 eV) and large optical absorption [8,9], evidencing its potentiality towards NLO devices in the broadband range. 2D GeP has been used as the excellent mode locker for 1.55-µm ultrashort pulse fiber laser [8].…”

“…Interestingly, 2D GeP has appealing properties of tunable bandgap structure (0.51-1.68 eV) and large optical absorption [8,9], evidencing its potentiality towards NLO devices in the broadband range. 2D GeP has been used as the excellent mode locker for 1.55-µm ultrashort pulse fiber laser [8]. On the other band, the reports on GeP-based photonic devices applied in ultrafast fiber laser at mid-infrared bands are limited.…”

“…Furthermore, the combination of chaotic multiple-pulse dynamics and highly nonlinear effects in the fiber laser cavity are also favorable for generating optical RWs [39,40]. Recently, the researchers have established that 2D GeP possesses not only the broadband nonlinear saturable absorption performances, but also stronger NLO responses [8], depicting its promising potential in optical RWs generation. Moreover, the 2D GeP-decorated microfiber photonic devices (GMPDs) have evidenced special structures with long-interaction length between light and 2D GeP material [41], effectively enhancing the nonlinear action for the multiple-pulse formation in ultrafast fiber lasers.…”

Zero‐Dimensional MXene‐Based Optical Devices for Ultrafast and Ultranarrow Photonics Applications

“…The normalized transmittance and input peak intensity of MXene Ti 3 C 2 T x QDs are shown in Figure 3d-f. Before we started the experiments of MXene Ti 3 C 2 T x QDs, we measured the nonlinear optical properties of solvent (IPA), and the experiment results confirm that the pure solvent not has saturable absorption properties, which is consistent with our previous works. [33,52,53] The pure solvent nonlinear optical response is displayed in Figure S3, Supporting Information. Eventually, the MXene QDs linear and nonlinear optical parameters are shown in Table 1, which demonstrates the MXene QDs is an excellent SA.…”