Coherent optical MIMO (Invited Paper)

Abstract

In this paper we present a Coherent Optical Multiple-Input Multiple-Output (COMIMO) communication system and its ability to exploit the inherent information capacity of Multi-Mode Fiber (MMF). COMIMO technique is a promising approach to unlock the information capacity of MMF as it ensures the necessary diversity for practically any fiber length. When exceeding the bandwidth-length product of the link, MIMO adaptive equalization can be used to mitigate inter-symbol interference (ISI). Furthermore, COMIMO link provides additional security in the physical layer that complements encryption.

Coherent Multi Channel Transmission over Multimode-Fiber and Related Signal Processing

“…If (1) incoherent transmitters will be used such as different intensity modulated laser diodes, strong degradation by beat-noise will occur, as it was experimentally demonstrated in [7] and application for MGD and low mode coupling appears favorable. In the case of (2) coherent transmitters, all optical carriers are coming from the same lower linewidth laser source and are modulated by different external modulators [2]. Even in this case, either (i) direct detection (DD) receivers for intensity modulated symbols (bits) or phase modulated RF subcarrier (RF-SC) can be applied.…”

“…To overcome these fundamental capacity limitations of the multimode fiber (MMF) introduced by modal delay (DMD), the exploitation of the transport on different fiber modes is topic of intense research since several years for access networks [1][2][3]. Recently this exploitation of the space domain has also been re-formulated for ultra-high bitrate transmission to conform the steadily growing demand for capacity in metro and core network [4 5].…”

Design of compact mode splitters using identical coupled waveguides with slots

“…An alternative approach could be the adaptation of multiple-input multiple-output signal processing over multimode fibers (MMFs) [4]. In this case, mode selective couplers [5] or filters [6] can be used to excite different signal channels as different modes of a MMF and thus form independent data channels in a MMF [7]. However, generation of a specific mode in a MMF can also excite unexpected higher order modes, and this would degrade the transmission quality of the MMF [8].…”

Simulation of properties of the transverse modal electric field of an infinite parabolic multimode fiber

“…Hence, the understanding and visualization of the transverse modal electric field (TMEF) of an infinite parabolic MMF may not be readily intuitive. The simulation is valuable for researchers analyzing various aspects of the TMEF, particularly for dispersion control [2, 8–10], spatial multiplexing [11–15], diversity multiplexing [16–19], and beam shaping [20, 21].…”