Colorless WDM-PON Using Single Side Band Carrier Suppressed Signals Mitigating Carrier Rayleigh Backscattering

A new scheme is offered for minimizing carrier Rayleigh backscattering(CRB) in single feeder fiber based wavelength division multiplexed passive optical network(WDM-PON). The proposed scheme is based on single side band carrier suppressed(SSBCS) signal, both at network and receiver sides, used for the first time at optical line terminal(OLT) and optical network unit(ONU) sides. We use dual-drive Mach-zehnder modulator(DD-MZM) for generating SSB-CS signals, which decreases the expense per bit in full transmission. SSB-CS mitigates CRB, both at OLT and ONU sides, because of having no chance of reflections from the carrier. Since no extra dedicated RF or laser source is used at ONU side, we thus achieve cost effective colorless WDM-PON system. Suppressed signals from four channels, each of 10 Gbps, are multiplexed before injecting into the fiber span of 25 km at OLT. At ONU side, half of the downlink power is used for re-modulating the data signal. The simulation results show an errorfree transmission. Moreover, the detailed power budget calculations show that the proposed scheme can be sought out for splitting ratio up to 128. Hence it offers enough system's margin for unseen losses.

Low-Cost Metamaterial Loaded Microstrip Antenna for Defense Applications

We have designed a Metamaterial unit-cell for 9 GHz frequency. Periodic structure was used at 4.25 × 4.25 mm with a thickness of 0.35 mm and giving us the 99.99% of absorbance at 9 GHz in simulated results. We have implemented a rectangular microstrip antenna and loaded it with Metamaterial unit-cells which provided improved results. There were results available for reflection coefficient (s11 parameter) at 9 GHz and also helping for the reduction of the Radar Cross Section of an antenna, which reduced more than 20 dB and not affected its directivity and gain.

Micro/nano-fiber-based source of heralded single photons at the telecom band

We experimentally demonstrate a heralded single photon source at 1290 nm by exploiting the spontaneous four wave mixing in a taper-drawn micro/nano-fiber（MNF）. Because the frequency detuning between the pump and heralded single photons is ~58 THz, the contamination by Raman scattering is significantly reduced at room temperature. Since the MNF is naturally connected to standard single mode fibers via fiber tapers, the source would be compatible with the existing fiber networks. When the emission rate of heralded signal photons is about 4.6 kHz, the measured second-order intensity correlation function g（2）（0） is 0.017 ± 0.002, which is suppressed by a factor of more than 55, relative to the classical limit.

Beyond 100 Gb/s Optical OFDM Transmitted in Optical Long-Haul System

100 G Ethernet is considered to become the next generation Ethernet standard for IP networks.Typical 100 Gb/s transmission systems and their performance are presented.Comparision and analysis for 100 Gb/s transmission systems have been discussed.It is demonstrated that optical OFDM can be used in future 100 Gb/s/ch and long-haul system.

On the applicability of the single parabolic band model to advanced thermoelectric materials with complex band structures

Due to the complex interplay between composition,synthesis parameters and the performance of thermoelectric materials,the optimization of thermoelectric materials needs to be complemented by modelling.A relatively simple and thus popular approach is the so called single parabolic band model,which allows for an efficient optimization of the material properties and a benchmarking of different materials based on relatively few,well available experimental results.As complex band structures are common for high performance materials,single parabolic band modelling is also employed with apparent success for material systems where the underlying assumptions are not well fulfilled.In order to assess the validity of a single parabolic band analysis for such systems,the thermoelectric properties for two model systems are calculated:one with a single band that is twofold degenerate and one with a light and a heavy band.Even if the density of states masses and the scattering potentials are kept identical,the transport properties and in particular the Hall coefficients differ significantly,which leads to an incorrectly determined carrier concentration.As the carrier concentration is the base for the single parabolic band analysis,all the quantities obtained from it(optimum carrier concentration,effective mass,deformation potential)are determined incorrectly as well.

Copper telluride with manipulated carrier concentrations for high-performance solid-state thermoelectrics

This study proposed a strategy for effectively diminishing the carrier concentration in Cu_(2)Te by introducing graphene sheets,Based on thermoelectric property measurements and single parabolic band modeling,the incorporated graphene effectively reduced the carrier concentration,not only enhancing the thermoelectric performance of the Cu_(2)Te/graphene composite but also substantially improving its figure of merit up to ~1.47 at 1000 K,which is 268% higher than that of pristine Cu_(2)Te,This study gives an insight into the control of carrier concentration and thermoelectric properties in Cu_(2)Te,and it could be extended to other copper chalcogenides for excellent thermoelectrics.