An overview of analog microwave photonics will be presented. The performance requirements for externally-modulated analog microwave photonic links will be reviewed with specific emphasis placed on modulator efficiency, laser noise, detected photocurrent, and link linearity.

http://ieeexplore.ieee.org/iel5/6387506/6403300/06403360.pdf

Microwave photonics

Hollow-core photonic crystal fibres have excited interest as potential ultra-low loss telecommunications fibres because light propagates mainly in air instead of solid glass. We propose that the ultimate limit to the attenuation of such fibres is determined by surface roughness due to frozenin capillary waves. This is confirmed by measurements of the surface roughness in a HC-PCF, the angular distribution of the power scattered out of the core, and the wavelength dependence of the minimum loss of fibres drawn to different scales.

/pdf/ultimate-low-loss-of-hollow-core-photonic-crystal-fibres-2k1vmtnkiy.pdf

Ultimate low loss of hollow-core photonic crystal fibres.

Lightwave communications is a necessity for the information age. Optical links provide enormous bandwidth, and the optical fiber is the only medium that can meet the modern society's needs for transporting massive amounts of data over long distances. Applications range from global high-capacity networks, which constitute the backbone of the internet, to the massively parallel interconnects that provide data connectivity inside datacenters and supercomputers. Optical communications is a diverse and rapidly changing field, where experts in photonics, communications, electronics, and signal processing work side by side to meet the ever-increasing demands for higher capacity, lower cost, and lower energy consumption, while adapting the system design to novel services and technologies. Due to the interdisciplinary nature of this rich research field, Journal of Optics has invited 16 researchers, each a world-leading expert in their respective subfields, to contribute a section to this invited review article, summarizing their views on state-of-the-art and future developments in optical communications.

/pdf/roadmap-of-optical-communications-22jmvturxy.pdf

Roadmap of optical communications

In this review we discuss the theoretical framework needed for studying the dynamical behaviour of semiconductor lasers exposed to three kinds of optical modulation. We start by a derivation of the single-mode rate-equations for the slowly varying complex electric field and the inversion, and the necessary extensions for monochromatic optical injection and normal external optical feedback. The basic operating characteristics of the solitary semiconductor laser are analysed, including light-current curves and their dependence on the spontaneous emission level, as well as the optical spectrum. The effect of monochromatic injection is discussed in terms of locking and non-locking dynamics, including a thermodynamic potential for phase jumps. The basic ingredients for studying external optical feedback are given, including a derivation of the thermodynamic potential for phase-diffusion. After an introduction on optical phase conjugation, the field rate-equation for feedback from a phase-conjugate mirror is derived.

http://iopscience.iop.org/article/10.1088/1355-5111/7/2/003/pdf

Semiconductor lasers with optical injection and feedback

Procedures are presented for estimating critical powers for nonlinear optical processes in single-mode fiber transmission systems. Crosstalk due to Raman gain in multiplexed systems can appear at powers of a few mW. The effects of self-phase modulation and stimulated Brillouin scattering can appear around 100 mW while typical stimulated Raman threshold powers are a few watts.

Nonlinearity in fiber transmission

A very low loss single-mode fibre with a minimum loss of 0.20 dB/km at a wavelength of 1.55 μm is attained; this loss reaches the ultimate lower loss limit of silica-based optical glass fibre. The loss mechanism is also discussed.

T. Miyashita

Papers

Ultimate low-loss single-mode fibre at 1.55 μm