Few-mode fibre-optic microwave photonic links

The fibre-optic microwave photonic link has become one of the basic building blocks for microwave photonics.Increasing the optical power at the receiver is the best way to improve all link performance metrics including gain,noise figure and dynamic range.Even though lasers can produce and photodetectors can receive optical powers on the order of a Watt or more,the power-handling capability of optical fibres is orders-of-magnitude lower.In this paper,we propose and demonstrate the use of few-mode fibres to bridge this power-handling gap,exploiting their unique features of small acousto-optic effective area,large effective areas of optical modes,as well as orthogonality and walk-off among spatial modes.Using specially designed few-mode fibres,we demonstrate order-of-magnitude improvements in link performances for single-channel and multiplexed transmission.This work represents the first step in few-mode microwave photonics.The spatial degrees of freedom can also offer other functionalities such as large,tunable delays based on modal dispersion and wavelength-independent lossless signal combining,which are indispensable in microwave photonics.

Direct fiber vector eigenmode multiplexing transmission seeded by integrated optical vortex emitters

Spatial modes have received substantial attention over the last decades and are used in optical communication applications.In fiber-optic communications,the employed linearly polarized modes and phase vortex modes carrying orbital angular momentum can be synthesized by fiber vector eigenmodes.To improve the transmission capacity and miniaturize the communication system,straightforward fiber vector eigenmode multiplexing and generation of fiber-eigenmode-like polarization vortices(vector vortex modes)using photonic integrated devices are of substantial interest.Here,we propose and demonstrate direct fiber vector eigenmode multiplexing transmission seeded by integrated optical vortex emitters.By exploiting vector vortex modes(radially and azimuthally polarized beams)generated from silicon microring resonators etched with angular gratings,we report data-carrying fiber vector eigenmode multiplexing transmission through a 2-km large-core fiber,showing low-level mode crosstalk and favorable link performance.These demonstrations may open up added capacity scaling opportunities by directly accessing multiple vector eigenmodes in the fiber and provide compact solutions to replace bulky diffractive optical elements for generating various optical vector beams.

Transmission of 200 Tb/s （375 × 3 × 178.125 Gb/s） PDM-DFTS-OFDM-32QAM super channel over lkm FMF

A few-mode fiber （FMF） is designed to support three spatial modes （LP01, LP 11a, and LP 11 b） and fabricated through plasma chemical vapor deposition （PCVD）and rod-in-tube （RIT） method. Using PDM-DFTS-OFDM- 32QAM modulation, wavelength division multiplexing, mode multiplexing, and coherent detection, we successfully demonstrated 200Tb/s （375× 3 × 178.125Gb/s） signal over 1 km FMF using C and L bands with 25 GHz channel spacing. After 1 km FMF transmission, all the tested bit error rates （BERs） are below 20% forward error correction （FEC） threshold （2.0 × 10-2）. Within each sub-channel, we achieved a spectral efficiency of 21.375 bits/Hz in the C and L bands.

Review on developments of novel specialty fibers： performance, application and process

This paper reviews the development progress of optical fiber, the producing and application of the specialty optical fiber in the world. Finally it states the leading technology of optical fiber of the world. Specialty optical fibers are series of optical fiber which could satisfy special requirements. Recently, the rapidly growing need from fiber to the home （FTTH）, sensors, active optical link, energy conversion and delivery and fiber laser attracts researchers and optical companies to explore more possibilities of optical fiber and some novel specialty optical fibers were invented for the efforts. Bending insensitive optical fiber with the ability of extreme 3 mm bending diameter makes it possible to use the optical fiber as the electric wire in some extremely compact devices. Higher power was achieved in the fiber laser field with the development of rare earth doped fiber. Nanomaterials such as Au particles and ZnO nanostructures were utilized to extend the application in sensors and energy conversion. Pure silica design was commercialized to improve the radiation resistance of sensors based on fiber optics.