Mingyi Gao

K-means-clustering-based fiber nonlinearity equalization techniques for 64-QAM coherent optical communication system.

In this work, we proposed two k-means-clustering-based algorithms to mitigate the fiber nonlinearity for 64-quadrature amplitude modulation (64-QAM) signal, the training-sequence assisted k-means algorithm and the blind k-means algorithm. We experimentally demonstrated the proposed k-means-clustering-based fiber nonlinearity mitigation techniques in 75-Gb/s 64-QAM coherent optical communication system. The proposed algorithms have reduced clustering complexity and low data redundancy and they are able to quickly find appropriate initial centroids and select correctly the centroids of the clusters to obtain the global optimal solutions for large k value. We measured the bit-error-ratio (BER) performance of 64-QAM signal with different launched powers into the 50-km single mode fiber and the proposed techniques can greatly mitigate the signal impairments caused by the amplified spontaneous emission noise and the fiber Kerr nonlinearity and improve the BER performance.

High-conversion-efficiency all-optical wavelength converter based on cascaded highly nonlinear fibers

All-optical wavelength converters based on parametric processing of highly nonlinear fiber (HNLF) can provide low energy consumption, fast process speed, and modulation format agnosticism. A longer HNLF with a larger nonlinear coefficient and high pump power will contribute to achieve higher conversion efficiency. However, the injected pump power to the fiber is limited by its stimulated Brillouin scattering threshold, where longer fibers always have lower threshold powers. In the paper, we propose an all-optical wavelength converter with higher conversion efficiency by cascading two different HNLFs. We experimentally achieved -8  dB conversion efficiency and good converted signals with negligible power penalties.

Seamless all-optical bidirectional wavelength converter

We proposed a seamless all-optical wavelength converter based on four wave mixing effect in highly nonlinear fibers. The proposed wavelength converter consists of a section of highly nonlinear fiber to implement bi-directionally wavelength conversion twice for seamless conversion. The seamless wavelength converter was utilized for orthogonal frequency division multiplexing signals with flexible spectra to defragment their optical spectra. The bidirectional scheme of the seamless wavelength converter costs less highly nonlinear fibers, so as to reduce the system size and cost.

Optimal Replica Servers Placement for Content Delivery Networks

A node-arc Mixed Integer Linear Programing (MILP) model is formulated for replica server placements and resource allocation in Content Delivery Networks (CNDs) which use anycast routing and multi-path transmissions and an efficient server-list-growth (SLG) algorithm for this is also proposed. Simulations indicate that the proposed approaches can balance the content delivery load and provide low transmission latency.

Pusle-width optimization of pulsed-pump fiber optical parametric amplifers

We investigated the effect of pulse width on pulsed-pump fiber optical parametric amplifiers. To achieve a high parametric gain, there is a trade-off between stimulated Brillouin scattering threshold power and self phase modulation effect.