Tremendous efforts have been developed for multi-Tbps over ultra-long distance and metro and access optical networks. With the exponential increase demand on data transmission, storage and serving, especially the 5G wireless access scenarios, the optical Internet networking has evolved to data-center based optical networks pressuring on novel and economical access transmission systems. This paper reports (1) Experimental platforms and transmission techniques employing band-limited optical components operating at 10G for 100G based at 28G baud. Advanced modulation formats such as PAM-4, DMT, duo-binary etc are reported and their advantages and disadvantages are analyzed so as to achieve multi-Tbps optical transmission systems for access inter- and intra- data-centered-based networks; (2) Integrated multi-Tbps combining comb laser sources and micro-ring modulators meeting the required performance for access systems are reported. Ten-sub-carrier quantum dot com lasers are employed in association with wideband optical intensity modulators to demonstrate the feasibility of such sources and integrated micro-ring modulators acting as a combined function of demultiplexing/multiplexing and modulation, hence compactness and economy scale. Under the use of multi-level modulation and direct detection at 56 GBd an aggregate of higher than 2Tbps and even 3Tbps can be achieved by interleaved two comb lasers of 16 sub-carrier lines; (3) Finally the fundamental designs of ultra-compacts flexible filters and switching integrated components based on Si photonics for multi Tera-bps active interconnection are presented. Experimental results on multi-channels transmissions and performances of optical switching matrices and effects on that of data channels are proposed.
In this work the use of two identical QD SOAs to enhance the performance of swept laser system for OCT applications is
discussed, resulting in an increase in bandwidth up to 94nm. The combination of GaAs based QD SOAs and InP based
QW SOAs for realizing broad bandwidth sources for OCT system is described. For the swept laser source a 154nm
spectral bandwidth from 1193nm to 1347nm and an average power of 8mW is obtained and for the filtered ASE source a
225 nm bandwidth is demonstrated.
Time-resolved photoluminescence decay measurements have been performed on samples with varying sized self-assembled InAs/GaAs quantum dot ensembles, formed by substrate mis-orientation alone, but otherwise under identical growth conditions. Ground-state radiative recombination lifetimes from 0.8 to 5.3 ns in the incident energy density range of 0.79 pJcm<sup>-2</sup> - 40 nJcm<sup>-2</sup> at a temperature of 77 K were obtained. It was found that a reduction of the quantum dot size led to a corresponding reduction of the radiative lifetime. The evident bi-exponential decay was obtained for the ground state emission of the quantum dot array, with the slower second component attributed to a carrier re-capturing and indirect radiative recombination processes. Also experimental evidence of the effect of the AlGaAs barrier in InAs QDs emitting in the wavelength range 1200-1300nm is presented. Time-resolved photoluminescence measurements have been performed on samples with different compositions of Al in the barrier. A full discussion of the lifetimes of these near infra-red emitting dots will be presented.