Mode switching using optically induced long-period gratings: a theoretical analysis

We show that optically induced long-period grating (OLPG) is a particular case of inter-modal Bragg-scattering four-wave mixing (BS-FWM). To carry out such analysis, a vector model for the inter-modal BS-FWM was proposed and further tailored to investigate the energy transfer induced by OLPGs. Both processes, BS-FWM and OLPGs, have been proposed for in-line all-optical mode switching in transmission systems with space-division multiplexing (SDM). In this scope, we demonstrate that the bandwidth of OLPGs is larger than the BS-FWM. Furthermore, we show that OLPG-based mode switching can take place in two windows, if both pump beams are launched near the zero value of the differential mode-group delay, and the central wavelength and the bandwidth of such windows can be tuned by properly adjusting the wavelength and the optical power of the pump beams. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

This study demonstrates that OLPG is a specific case of BS-FWM, proposing a vector model for analyzing the energy transfer induced by OLPGs within the inter-modal BS-FWM framework. It is shown that the bandwidth of OLPGs exceeds that of BS-FWM. Additionally, it is illustrated that mode switching based on OLPG can occur in specific windows, with the central wavelength and bandwidth of these windows being tunable by adjusting the wavelength and optical power of the pump beams.