Improved multimode link bandwidth using spatial diversity in signal reception

Summary form only given. The demands placed on LANs and the use of multimode fiber (MMF) in gigabit Ethernet has motivated development of differential mode delay (DMD) compensation. An adopted method of compensation uses a restricted mode launch, limiting the number of excited modes. This method can realize significant improvement in MMF links; however, it requires an optical transmitter optimized for single-mode fiber. Unfortunately, this precludes the use of multimode VCSELs, which can achieve the low cost of ownership required of LANs. In this paper, we propose and demonstrate spatially diverse detection, where multiple photodetectors are used to detect separate groups of modes. The weighted signals are recombined to compensate for DMD. Consequently, this method does not require strict control of the launch condition, i.e. it is compatible with VCSELs, and retains the alignment tolerance of MMF.