Adaptive control of waveguide modes in a few-mode fiber network

ABSTRACT We experimentally demonstrate adaptive control of linearly polarized (LP) modes based on a fiber Bragg grating (FBG), where feedback for the adaptive algorithm is provided by the optical signal transmitted through and reflected by the FBG. In this approach, by maximizing the ratio of optical power transmitted and reflected by the FBG, we can selectively excite the LP 01 and the LP 11 modes at an optical wavelength associat ed with the appropriate FBG reflection peak. Combining this method with time-division-multiplexing, it should be possible to adaptively control guided modes at any desired location within a multimode fiber network. Keywords: Adaptive optics, mode control, few mode fiber, fiber Bragg grating 1. INTRODUCTION Traditionally, single mode fiber (SMF) are highly preferred fo r important applications such as optical commination and sensing. However, with recent developm ent of mode-division-multiplexing (MDM), there has been renewed interest in multimode fibers (MMFs). For example, in MDM, different linearly polarized (LP) modes in few mode fibers (FMFs) have been utilized as a multiplexing parameter to increase the information capacity of optical communications