Delay-Spread Distribution for Multimode Fiber With Strong Mode Coupling

作者：Ho Keang Po^*; Kahn Joseph M

来源：IEEE Photonics Technology Letters, 2012, 24(21): 1906-1909.

DOI：10.1109/LPT.2012.2218280

• Delay spread
• mode-division multiplexing
• multimode fiber
• random matrices

In the strong mode coupling regime, the delay spread of multimode fiber is statistically the same as the difference between the maximum and minimum eigenvalues of a Gaussian unitary ensemble. We study the delay-spread distribution using three methods: 1) numerical evaluation of the Fredholm determinant; 2) numerical integration based on the Andreief identity; and 3) approximation based on the Tracy-Widom distribution. Results obtained using the Fredholm determinant and the Andreief identity are virtually indistinguishable. The approximation based on the Tracy-Widom distribution is sufficiently accurate for most engineering purposes when the number of modes is at least 12. In a digital equalizer, a memory length of four to five times the group-delay standard deviation is sufficient to ensure that the delay spread will exceed the equalizer memory length with a probability of less than 10(-4)-10(-6).

• 出版日期2012-11-1