Mode-field matched twin spot launch for enhancing data rates in multimode fibers

Mumtimode fibers (MMF) are increasingly used for high speed, short haul applications. Several techniques, both optical and electronic, are being researched to enhance the capacity of MMFs. This paper reports an improved version of the center-launching technique, viz. mode-field matched twin-spot launch, which can be used to excite the fundamental mode alone in an MMF. This technique reduces the differential mode delay (DMD) and gives higher bandwidth. One of the major advantages of the proposed technique over others is its higher misalignment tolerances of the order of 5 µm. The extinction ratio achieved at 5 µm is greater than 9 dB, with much higher values for lesser misalignments.