Synthesis of photonic crystal fiber based on graphene directly grown on air-hole by chemical vapor deposition

The integration of fiber with graphene has greatly expanded the two-dimensional functional materials in the field of photonics research. However, the growth method by using chemical vapor deposition with metal catalytic substrateis limited to the fabrication of a graphene-fiber composite due to inevitably transferring graphene flakes onto the optical fiber surface. In order to fully achieve the interaction between light and graphene material, optical fibers have to be treated with special structure, which greatly damages the fiber structure, resulting in inefficient and harmful manufacturing strategy for the mass production. In this paper, a graphene-photonic crystal fiber (G-PCF) composite is prepared by atmospheric chemical vapor deposition (APCVD), which can directly grow monolayer and multi-layer graphene into the air-hole of photonic crystal fiber. Furthermore, we randomly break a G-PCF and then conduct an electron microscope (SEM) test at the fractured section. It is obvious that a tube-like graphene protruding out of one hole in the fractured area of the G-PCF is observed, thus further demonstrating that a monolayer graphene is grown on the inner hole walls of the PCF as shown in <xref ref-type="fig" rid="Figure2">Fig. 2</xref>. By changing the process parameters such as growth temperature, duration and gas flow rate of carbon source, the law of the influence of different parameters on the graphene layers is explored. In addition, the uniformity of graphene and defects in the graphene-photonic crystal fiber(G-PCF) are experimentally analyzed. As illustrated in <xref ref-type="fig" rid="Figure7">Fig. 7</xref>, a 4-cm-long uniform graphene-photonic crystal fiber sample is achieved by controlling the gas flow rate, growth time and the growth temperature. The APCVD method of directly growing graphene onto the inner hole walls of the PCF is simple and effective. The flexible structure and optical control enable the G-PCF to have great potential applications in all-optical devices and photonics. The development of high-quality graphene synthesis and opto-electronics technology ensures its compatibility with the integrated electronics platform and existing optical fiber systems. Moreover, our results will pave the way for 2<i>D</i> materials and optical fiber applications, providing a new idea for the application of graphene to the integration of all-optical fibers.