All-fiber cylindrical vector beams laser based on an acoustically-induced fiber grating

Abstract

Abstract We presented a method to construct an all-fiber laser by using an acoustically-induced fiber grating (AIFG) in two-mode fiber (TMF) within the laser cavity to generate cylindrical vector beams (CVBs) in communication band. Based on the polarization dependent vector mode coupling characteristic of an AIFG, the CVBs were generated by respectively coupling <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi mathvariant="normal">HE</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>11</mml:mn> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">x</mml:mi> </mml:mrow> </mml:msubsup> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi mathvariant="normal">HE</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>11</mml:mn> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">y</mml:mi> </mml:mrow> </mml:msubsup> </mml:math> modes to TM 01 and TE 01 modes, which have radial and azimuthal polarizations characteristics, respectively. The output of the all-fiber laser could be adjusted from a linearly-polarized Gaussian mode to a radially or an azimuthally polarized vector mode through a polarization controller to adjust the linear polarization direction of the input mode of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi mathvariant="normal">H</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>11</mml:mn> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">x</mml:mi> <mml:mo stretchy="true">/</mml:mo> <mml:mi mathvariant="normal">y</mml:mi> </mml:mrow> </mml:msubsup> </mml:math> and an acoustic flexural wave applied on TMF. This work provides a method for generating CVBs with convenient mode conversion characteristics.