Ultra-broadband mid-infrared TE01 vector mode selector based on ring-core few-mode photonic crystal fiber

A mid-infrared TE(01 )vector mode selector based on chalcogenide ring-core few-mode fiber is proposed and investigated numerically by the finite element method (FEM). By embedding metal composite nanowire in the PCF core to generate surface plasmon resonance, TE01 vector mode could propagate due to low loss transmission, whereas the fundamental mode, TM01 and HE21 modes could hardly be maintained due to high loss. The effects of structural parameters on mode transmission characteristics and mode loss in photonic crystal fibers in the mid infrared wavelength range are investigated. Under the optimal structural parameters, the loss ratios of each mode to TE01 mode are more than 50 in the waveband range from 2 to 3 mu m, which means the TE01 single-mode transmission can be maintained in ultra-wide mid-infrared band. The designed fiber can be connected with the mid-infrared laser as a vector mode selection device to efficiently output pure TE01 mode cylindrical vector beam, which makes preferable application in mid-infrared optical communication, optical capture, super resolution imaging, biochemical sensing and other fields.