Selective transverse mode emission from all polarization-maintaining fiber lasers

We demonstrated an all polarization-maintaining fiber (PMF) laser which could offer selective transverse mode emission. Offset and cross splicing between PMF sections was used to generate higher order mode and to yield a birefringence induced mode filter. Polarization rotation technique (PRT) was used to select the output beam profile. Both linear cavity and ring cavity were explored. Experimentally, 360{\deg} rotating LP11 mode and OAM vortex beam with plus and minus 1 topological charges have been realized from an all PMF linear cavity laser and a ring cavity laser respectively.