SOA Direct Modulation in Wavelength-Selectable Laser Array Light Sources

We demonstrated, for the first time, 2.5-Gb/s SOA direct modulation in the wavelength-selectable DFB laser array. The SOA direct modulation was achieved in the wide tuning range of 22.7nm by selecting arrayed laser and tuning the temperature. 40-km transmission was also confirmed..

Experimental demonstration of a flexible-grid 1×(2×3)mode-and wavelength-selective switch using silicon microring resonators and counter-tapered couplers

A flexible-grid 1×(2×3)mode-and wavelength-selective switch which comprises counter-tapered couplers and silicon microring resonators has been proposed,optimized,and demonstrated experimentally in this work.By carefully thermally tuning phase shifters and silicon microring resonators,mode and wavelength signals can be independently and flexibly conveyed to any one of the output ports,and different bandwidths can be generated as desired.The particle swarm optimization algorithm and finite difference time-domain method are employed to optimize structural parameters of the twomode(de)multiplexer and crossing waveguide.The bandwidth-tunable wavelength-selective optical router composed of12 microring resonators is studied by taking advantage of the transfer matrix method.Measurement results show that,for the fabricated module,cross talk less than-10.18 dB,an extinction ratio larger than 17.41 d B,an in-band ripple lower than0.79 dB,and a 3-dB bandwidth changing from 0.38 to 1.05 nm are obtained,as the wavelength-channel spacing is 0.40 nm.The corresponding response time is measured to be 13.64μs.

Design of low-energy on-chip electro-optical 1 × M wavelength-selective switches

A theoretical design is presented for a 1 × M wavelength-selective switch(WSS) that routes any one of N incoming wavelength signals to any one of M output ports. This planar on-chip device comprises of a 1 × N demultiplexer, a group of N switching "trees" actuated by electro-optical or thermo-optical means, and an M-fold set of N × 1multiplexers. Trees utilize 1 × 2 switches. The WSS insertion loss is proportional to [log_2(M+N +1)]. Along with cross talk from trees, cross talk is present at each cross-illuminated waveguide intersection within the WSS, and there are at most N-1 such crossings per path. These loss and cross talk properties will likely place a practical limit of N=M=16 upon the WSS size. By constraining the 1 × 2 switching energy to^1 f J∕bit, we find that resonant, narrowband 1 × 2 switches are required. The 1 × 2 devices proposed here are nanobeam Mach–Zehnders and asymmetric contra-directional couplers with grating assistance.

40 Gbit/s Transparent Network Based on Wavelength-Selective Optical Cross Connect

This paper discusses a 40-Gbit/s transparent optical network focusing on the optical transport performance. We show 1200-km transmission with two WSOXC' sspaced by 400 km. In addition, network control issues are briefly addressed.

Brillouin wavelength-selective all-optical polarization conversion

The manipulation of the polarization properties of light in guided media is crucial in many classical and quantum optical systems.However,the capability of current technology to finely define the state of polarization of particular wavelengths is far from the level of maturity in amplitude control.Here,we introduce a light-by-light polarization control mechanism with wavelength selectivity based on the change of the phase retardance by means of stimulated Brillouin scattering.Experiments show that any point on the Poincare sphere can be reached from an arbitrary input state of polarization with little variation of the signal amplitude(<2.5 dB).Unlike other Brillouin processing schemes,the degradation of the noise figure is small(1.5 dB for a full 2πrotation).This all-optical polarization controller can forge the development of new polarization-based techniques in optical communication,laser engineering,sensing,quantum systems,and light-based probing of chemical and biological systems.

Diffusion dynamics and characterization of attogram masses in optically trapped single nanoparticles using laser-induced plasma imaging

In the present work,a wavelength-selected plasma imaging analysis system is presented and used to track photons emitted from single-trapped nanoparticles in air at atmospheric pressure.The isolated nanoentities were atomized and excited into plasma state using single nanosecond laser pulses.The use of appropriate wavelength filters alongside time-optimized acquisition settings enabled the detection of molecular and atomic emissions in the plasma.The photon detection efficiency of the imaging line resulted in a signal>400 times larger than the simultaneously-acquired dispersive spectroscopy data.The increase in sensitivity outlined the evolution of diverse physicochemical processes at the single particle scale which included heat and momentum transfer from the plasma into the particle as wells as chemical reactions.The imaging detection of excited fragments evidenced different diffusion kinetics and time frames for atoms and molecules and their influence upon both the spectroscopic emission readout and fabrication processes using the plasma as a reactor.Moreover,the origin of molecular species,whether naturally-occurring or derived from a chemical reaction in the plasma,could also be studied on the basis of compositional gradients found on the images.Limits of detection for the inspected species ranged from tens to hundreds attograms,thus leading to an exceptional sensing principle for single nanoentities that may impact several areas of science and technology.

Novel applications of space-division multiplexing

Space-division multiplexing （SDM） using multi-core fibers （MCFs） and few-mode fibers （FMFs） was proposed as a solution to increase capacity and/or reduce the cost per bit of fiber-optic transmission. Advances in passive and active SDM devices as well as digital signal processing have led to impressive SDM transmission demonstrations in the laboratory. Although the perceived advantages in terms of capacity and cost per bit that SDM offers over parallel SMF bundles are not universally accepted, SDM is beginning to emerge as an indispensable solution in major network segments. The introduction of the spatial degree of freedom allows optical networks to overcome fundamental limitations such as fiber nonlinearity as well practical limitations such as power delivery. We describe these application scenarios that the optical communications industry has already began to explore. From a fundamental science point of view, concepts such as the principal modes, generalized Stokes space, and multi-component solitons discovered in SDM research will likely have a broad impact in other areas of science and engineering.