Related Experiment Video
Updated: Aug 15, 2026

Writing Bragg Gratings in Multicore Fibers
Published on: April 20, 2016
Design of weakly-coupled 3-mode 4-core fibers with low differential mode delay for the C + L band using a
Abstract:
We investigate weakly-coupled 3-mode 4-core fibers for the C + L band, comparing graded-index (GI) and dual-step-index (DSI) core profiles with a focus on differential mode delay (DMD) reduction. While both profiles are effective for minimizing DMD in 3-mode transmission, we found that it is difficult for GI profiles with a profile exponent of around 2 to satisfy both the cutoff and low-loss conditions for 3-mode transmission across the entire C + L band. In contrast, the DSI profile offers a higher degree of design freedom and superior controllability over the wavelength dependence of DMD. Furthermore, we demonstrate that a common-depressed cladding layer effectively relaxes cutoff conditions for both GI and DSI core profiles. By replacing a previously reported weakly-coupled 3-mode 4-core step-index fiber with the DSI profile, we achieved inter-core crosstalk (XT) < -50 dB/km while maintaining DMD < 60 ps/km across the entire C + L band.
More Related Videos
Related Concept Videos
Transmission Line Design Considerations
Fiber Reinforced Concrete
Induced Electric Dipoles
Since the absolute value of potential energy holds no physical meaning, its zero value can be chosen as per...
Design Example: Underdamped Parallel RLC Circuit
Starting with a fixed...
Inductance: Solid Cylindrical Conductor
Given the uniform current distribution, the magnetic field Hx and flux density Bx inside the conductor are...
Mutual Inductance
When two circuits carrying time-varying currents are close to one another, the magnetic flux through each circuit varies because of the changing current in the other circuit. Consequently, an emf is induced in each circuit by the changing current in the other. Therefore, this type of emf is called...

