The tremendous growth of data traffic has spurred a rapid evolution of optical communications for a higher data transmission capacity. Next-generation fiber-optic communication systems will require dramatically increased complexity that cannot be obtained using discrete components. In this context, silicon photonics is quickly maturing. Capable of manipulating electrons and photons on the same platform, this disruptive technology promises to cram more complexity on a single chip, leading to orders-of-magnitude reduction of integrated photonic systems in size, energy, and cost. This paper provides a system perspective and reviews recent progress in silicon photonics probing all dimensions of light to scale the capacity of fiber-optic networks toward terabits-per-second per optical interface and petabits-per-second per transmission link. Firstly, we overview fundamentals and the evolving trends of silicon photonic fabrication process. Then, we focus on recent progress in silicon coherent optical transceivers. Further scaling the system capacity requires multiplexing techniques in all the dimensions of light: wavelength, polarization, and space, for which we have seen impressive demonstrations of on-chip functionalities such as polarization diversity circuits and wavelength- and space-division multiplexers. Despite these advances, large-scale silicon photonic integrated circuits incorporating a variety of active and passive functionalities still face considerable challenges, many of which will eventually be addressed as the technology continues evolving with the entire ecosystem at a fast pace.

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InP-based uni-traveling-carrier photodiodes (UTC-PDs) with novel dipole-doped structure to achieve high photocurrent as well as wide bandwidth are demonstrated in this work. The dipole-doped layers in combination with a 22-nm-thick undoped InGaAs setback layer were employed at the InGaAs/InP absorption and collection interface to reduce the current blocking effect. A high photocurrent of 160 mA with 1.9 GHz 3-dB bandwidth from a 70-µm -diameter top-illuminated UTC-PD is achieved. A large 3-dB bandwidth of 62.5GHz, which is estimated with an equivalent circuit model, has also been obtained from a 12-µm -diameter UTC-PD device. The results demonstrate that the dipole-doping can serve as an effective alternative to the quaternary InGaAsP layer at InGaAs/InP interface for InP-based UTC-PD to suppress the current blocking and reduce the complexity in epi-layers growth and device fabrication. Index Terms-Dipole-doped layer, high speed, photocurrent, uni-traveling-carrier photodiodes (UTC-PDs), 3-dB bandwidth. I. INTRODUCTIONIGH-photocurrent and high-speed photodiodes (PDs) have attracted intensive research interests for the application of CATV network, photonic analog-to-digital converter and optical links to phased array antenna [1,2]. To meet the requirements for both high photocurrent and high speed operation, various types of photodiodes have been investigated. Conventional PIN-PD [3] is one of the simplest PD structures which is used for a wide range of applications. In a conventional PIN-PD structure, both electrons and holes are photo-generated in the depletion layer. The holes with much lower drift mobility and velocity, contribute dominantly to the space charge and can result in the degradation of device performance, especially under high power illumination [1].Hence, Ishibashi et al. [1] proposed a new type of photodiode -uni-traveling-carrier photodiode (UTC-PD) which could

Previous research on orthogonal matching pursuit (OMP) algorithm mainly focuses on the recovery performance of a sparse signal x given an acquired model y = Fx + n. A general perturbation model y = (F + E)x + n in addition to the above acquired model exists, where E is the measurement perturbation. For this general perturbation model, the new restricted isometry constant of OMP algorithm is shown.

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