Design and fabrication of restricted mode launching device for high-speed multimode fiber link

Fabrication of Y-Branched GI Core Polymer Waveguide and its Application to CWDM MUX Device for Multimode Fiber

“…As described in [15], modal dispersion reduction is possible by controlling the MPD in MMFs. The MPD is calculated by partially differentiating the encircled flux (EF) with the normalized radius.…”

“…Applying the measured EF curves, the effective modal bandwidth (EMBc) is calculated in order to quantitively verify the RML exciter function. As reported in [15,16,19], the EMBc is calculated by multiplying the differential mode delay (DMD) of a tested MMF with the MPD. Since we investigate the possibility of longer-reach transmissions using widely deployed MMFs, the empirically measured DMD pulse waveform of a 1000-m long OM3 fiber is applied.…”

“…However, if the launch beam is focused to a small S.S. using a simple lens system, the numerical aperture (NA) of the launch beam tends to increase, which could also launch the higher order modes in GI-MMFs. We have shown that a lower-NA launch beam as well as a small S.S. is required to achieve higher MMF modal bandwidth [15,16]. To realize a small S.S. with a low launch NA, an RML exciter applying an adaptive optics system inserted between VCSEL and MMF has already been proposed [17].…”