The DMD and loss parameter α can be further reduced in a future optimized fabrication. A few other groups have also developed FMF with improved performances [6–7]. Very recently a novel TMF fiber is designed with low-DMD, low-mode coupling and low-loss TMF using a graded-index core and double cladding structure [16] as shown in Fig. 3. The graded-index core design helps reducing the DMD, and the trenched cladding structure facilitate low loss for LP11 modes. The DMD between LP01 and LP11 is measured as small as 0.076 ps/m, and loss for both LP01 and LP11 is lower than 0.2 dB/km.