Single-mode microstructured lightguides with circular placement of cavities for radiation transport in the limited-nonlinearity regime

This paper theoretically and experimentally analyzes the possibilities of quartz glass microstructures with nonhexagonal (circular) orientation of the cavities in the cladding and a 40-μm-diameter core in order to improve the weak directionality of the fundamental mode. It is established that the criterion for reaching the single-mode regime of radiation propagation is a high discrimination level of the TM01 polarization component of the first upper mode.