This paper highlights the challenges involved when designing, manufacturing and testing ultra-long high capacity submarine telecommunication systems. We will focus on the transpacific design space and use as an example the design data and measurement results from the most advanced deployed undersea communication link - a 9000 km transpacific segment built using dispersion slope managed fiber. A discussion of recent technical advances and even longer systems, for direct, all optical, wideband connections between the United States and Asia is also included.
In this paper we investigate the maximum unrepeatered and uncompensated transmission on standard single mode fiber (SSMF) with single-sideband (SSB) modulation. To increase the optical signal to noise ratio (OSNR) we use a backward pumping Raman source. With the combination of both the bandwidth reduced modulation scheme and the OSNR improvement with Raman amplification we can enlarge the error-free uncompensated and unrepeatered transmission length for SSB modulation up to 200km.
We have performed ultrafast three-pulse experiments in order to investigate the relaxation of charge carriers from a non-equilibrium distribution in inverted GaAs multiple quantum wells. The first pulse, used to create optical gain, was followed by a conventional pump-probe study. The pump-induced spectral hole inside the optical gain was accompanied by sidebands which occurred about 39 meV above the original spectral hole. These sidebands can be explained in terms of LO-phonon scattering of the charge carriers into the vacancies of the spectral hole.
We present a model for gain in a quasi zero-dimensional quantum confined semiconductor system. Due to a multitude of one-electron-hole pair and two-electron-hole pair transitions, the gain region is broad, quasi-continuous and stretches below the absorption edge. Femtosecond experiments in the gain region of strongly confined CdSe quantum dots confirm our theoretical predictions.