Increase In Transmission Distance Research Articles

Research on the coherence of partially coherent radially polarized beam during propagation

Based on the generalized Huygens theory and the unified theory of coherence and polarization, study is made on the module value of complex degree of coherence of partially coherent radially polarized beam (PCRPB) which changes with transmission distance at different reference point. Results show that the module value distribution of the complex degree changing with the transmission distance is different for different reference point while PCRPB propagates in a free space. When the reference point is at the origin, with the increase of the transmission distance, μxx and μxy hold a symmetric distribution, and the distribution range increases. When the reference point is confined on the x-axis, μxx changes from single peak to three peaks, and the two valleys lie symmetrically; and μxy changes from two peaks to four peaks, and the four valleys lie symmetrically. The transmission distance of the evolution is related to the distance between the reference point and the origin: the closer the distance between the reference point and the origin, the shorter the transmission distance is needed to achieve the evolution process. When the reference point lies on the y-axis, μxx holds a symmetric distribution, its distribution range increases, and μxy changes from two peak values to four peaks and four valleys which are in symmetric form. The transmission distance is related to the spacing between the reference point and the origin, the closer the distance between the reference point and the origin: the shorter the transmission is needed to achieve the evolution process. In addition, when the reference point lies at other positions on the observation plane, the module value distribution of μxx and μxy is obtained by combining the distribution rules of reference point at x-axis and y-axis: i.e., when the reference point lies at other positions of the observation plane, the module values μxx and μxy can be composed of three peaks and four peaks with the increase of transmission distance, respectively.

A Novel AC/DC Bridgeless and Contactless Electrical Energy Transmission System for Multi-load Applications

In this paper, a novel AC/DC bridge-less and contact-less energy transmission system is proposed. The coreless planar transformer and magnetic dipole moment are applied to transmit electrical energy in non-contact manner. In addition, the input ac current of proposed converter has good power factor correction. Simultaneously, the primary-side switches have zero-voltage switching and the secondary-side diodes have zero-current transition. Thus, the power quality and efficiency of proposed contactless electrical energy transmission system can be upgraded. Furthermore, the proposed contactless electrical energy transmission system also can increase transmission distance with the voltage multiplier receiver connected in the rear of the secondary-side coreless planar transformer. Both the power transmission and circuit operation are explained in this paper. Finally, a prototype system is constructed and the validity has been confirmed with experiment and practical measurements.

Cascaded phase-preserving multilevel amplitude regeneration.

The performance of cascaded in-line phase-preserving amplitude regeneration using nonlinear amplifying loop mirrors has been studied in numerical simulations. As an example of a spectrally efficient modulation format with two amplitude states and multiple phase states, the regeneration performance of a star-16QAM format, basically an 8PSK format with two amplitude levels, was evaluated. An increased robustness against amplified spontaneous emission and nonlinear phase noise was observed resulting in a significantly increased transmission distance.

Wireless Energy Transfer Through Magnetic Reluctance Coupling

Energy harvesting from human motion for body worn or implanted devices faces the problem of the wearer being still, e.g. while asleep. Especially for medical devices this can become an issue if a patient is bed-bound for prolonged periods of time and the internal battery of a harvesting system is not recharged. This article introduces a mechanism for wireless energy transfer based on a previously presented energy harvesting device. The internal rotor of the energy harvester is made of mild steel and can be actuated through a magnetic reluctance coupling to an external motor. The internal piezoelectric transducer is consequently actuated and generates electricity. This paper successfully demonstrates energy transfer over a distance of 16 mm in air and an achieved power output of 85 μW at 25 Hz. The device functional volume is 1.85 cm3. Furthermore, it was demonstrated that increasing the driving frequency beyond 25 Hz did not yield a further increase in power output. Future research will focus on improving the reluctance coupling, e.g. by investigating the use of multiple or stronger magnets, in order to increase transmission distance.

A study of green wavelength-division multiplexed optical communication systems using cascaded fiber bragg grating

This paper studies the performance analysis of wavelength-division multiplexed optical communication systems (WDM). First, flat-gain erbium doped fiber amplifiers (EDFAs) are seriously needed to obtain proper and equal amplification of all channels. Such amplifiers can be designed by intrinsically modifying the host material or extrinsically using proper filters. In this research, we benefit from both the intrinsic and extrinsic methods to achieve sharp flat EDFA output gain using cascaded fiber Bragg gratings (FBGs). Second, the performance of our technique has been evaluated through calculating the bit error rate (BER) and signal-to-noise ratio (SNR) of a WDM system embedded with the reported EDFA flattening system. The parametric simulations of the FWHM of FBGs, SNR, optical power and the transmission distance have shown a noticeable improved performance. Sending data via an optical WDM system will be proven from comprehensive simulations to achieve high quality signal transmission spectrums, increased transmission distances and low power consumption. By extension, the reported design using cascaded FBGs can also be generalized to equalize the gain of any arbitrary profile.

End-to-End Energy Modeling and Analysis of Long-Haul Coherent Transmission Systems

In this paper, we model and analyze the end-to-end energy consumption of 100-Gbps coherent long-haul transmission systems. In particular, we investigate the impact of forward error correction (FEC) on the end-to-end energy consumption. We compare the energy efficiency of commonly used modulation formats in 100-Gbps transmission, namely dual polarization-quadrature phase-shift-keying (DP-QPSK) and dual polarization-16-quadrature amplitude modulation (DP-16-QAM), for different transmission distance and input bit error rate. Our energy model includes consumption of transmitter, booster, link amplifier as well as receiver. Compared with previous digital signal processing models, we provide a very detailed model that not only includes all the significant functional blocks (such as timing and carrier recovery, chromatic and polarization mode dispersion compensation, and FEC), but also takes into account impact of the number of samples processed every clock cycle and of operations other than multiplications. We have found that receiver energy consumption dominates in transmission systems that use electronic dispersion compensation over long transmission distances. Our results show that for short transmission distances where hard-decision decoding is adequate for both modulation formats, DP-16-QAM is more energy efficient than DP-QPSK. However, as the transmission distance increases, the energy saving due to the low symbol rate of DP-16-QAM is offset by the energy consumption of soft-decision decoding. In this case, the two modulation formats have approximately similar energy consumption.

Experimental demonstrations of dual polarization CO-OFDM using mid-span spectral inversion for nonlinearity compensation.

We experimentally demonstrate fiber nonlinearity compensation in dual polarization coherent optical OFDM (DP CO-OFDM) systems using mid-span spectral inversion (MSSI). We use third-order nonlinearity between a pump and the signal in a highly nonlinear fiber (HNLF) for MSSI. Maximum launch powers at FEC threshold for two 10 × 80-km 16-QAM OFDM systems were increased by 6.4 dB at a 121-Gb/s data rate and 2.8 dB at 1.2 Tb/s. The experimental results are the first demonstration of using MSSI for nonlinearity compensation in any dual polarization coherent system. Simulations show that these increases could support a 22% increase in total transmission distance at 1.2-Tb/s system without increasing the number of inline amplifiers, by extending the fiber spans from 90 to 110 km. When spans of 80 km are used, simulations reveal that MSSI system performance shows less degradation with increasing transmission distance, and an overall transmission distance increase of more than 70% is expected using MSSI.

Magnetic Resonant Coupling Based Wireless Power Transfer System with In-Band Communication

This paper presents a design of a wireless power transfer system based on magnetic resonant coupling technology with in-band wireless communication. To increase the transmission distance and compensate for the change in the effective capacitance due to the varying distance, the proposed system used a loop antenna with a selectable capacitor array. Because the increased transmission distance enables multiple charging, we added a communication protocol operated at the same frequency band to manage a network and control power circuits. In order to achieve the efficient bandwidth in both power transfer mode and communication mode, the S-parameters of the loop antennas are adjusted by switching a series resistor. Our test results showed that the loop antenna achieved a high Q factor in power transfer mode and enough passband in communication mode.

Flow Field Simulation of the Nozzle and the Influence of Size

The nozzle is one of the critical parts in the dry-ice blasting system, spray nozzle's structure and the air supersonic free jet flow field take big influence on cleaning efficiency during the blasting process. Inner flow field of different size nozzles and the flow field of jet flow sprayed by nozzles were simulated with software Fluent, which obtained the distribution results of pressure and velocity of fluid. The result indicated that the supersonic underexpanded jet take place in the nozzle outlet and the shock wave is gained as the pressure at the nozzle exit is greater than the atmospheric pressure. With increasing of the nozzle size, the velocity decrease of airflow become slower, the shock wave transmission distance increase and deduce the stability of the jet flow.

Simulation and Calculation of 10.6μm Laser Time Broadening and Space Broadening Characteristics in Near-Earth Dust

Based on the Mie scattering theory and the gamma size distribution model, 10.6μm laser scattering characteristics in dust particles are calculated and analyzed.On this basis,the time broadening and space broadening characteristics of the laser are analyzed by using Monte Carlo method.Transmittance change with the transmission distance are quantitative calculated and the time detention and space broadening characteristics of the laser passed through dust for different transmission distances are calculated and analyzed. The results show that the transmittance decreases with increasing transmission distance, and the transmittance is close to 0 when transmission distance is close to 200m; The time delay of 10.6μm laser is more significant with the increaseing transmission distance; The space broadening of 10.6μm laser is more obvious and the energy is more dispersed with the increaseing transmission distance.

Improved Quadrature Duobinary System Performance Using Multi-Modulus Equalization

Quadrature duobinary (QDB) signals can be generated from strongly filtered quadrature phase shift keying whose constellation becomes a 9-ary quadrature amplitude modulation. In this letter, the performance of multi-modulus equalization (MMEQ) to suppress noise and crosstalk for this QDB signal is experimentally investigated and compared with that of the constant-modulus equalization (CMEQ) with post filtering, under different filter bandwidth and carrier spacing. The results show that the MMEQ scheme has better performance for noise and crosstalk suppression, resulting in improved filtering tolerance. This improved filtering tolerance is demonstrated in an 8-channel 112-Gb/s wavelength-division-multiplexing experiment with a 25-GHz grid over 2640-km single-mode fiber. Compared with the regular CMEQ with the post filtering scheme, 1-dB optical signal-to-noise ratio improvement at the bit-error-ratio (BER) of $1\times 10^{-3}$ and 32% increased transmission distance at the BER level of $3.8\times 10^{-3}$ for forward-error-correction are obtained for the MMEQ scheme.

Simulation of fiber to the home triple play services at 2 Gbit/s using GE-PON architecture for 56 ONUs

This paper evaluates and compares FTTH (Fiber To The Home) GEPON (Gigabit Ethernet Passive Optical Network) link design for 56 subscribers at 20km reach at 2Gbps bit rate. A 1:56 splitter is used as a PON (Passive Optical Network) element which creates communication between a Central Office to different users and. A boosting amplifier is employed before fiber length which tends to decrease BER and allows more users to accommodate. This architecture is investigated for different values of data rate from a CO (Central Office) to the PON in terms of BER (Bit Error Rate). The simulation work reports BER of 4.5246e−009 at 2Gbit/s systems for the case of 56 users and if we further increase data rate of system say 5Gbps, then we observe a sharp increase in BER. Similarly in the variation of BER with respect to transmission distance, we observe that BER shows an increase in its value as transmission distance increases.

Performance Study of 1 Tbits/s WDM Coherent Optical OFDM System

This paper investigates the architecture of Tbits/s Wavelength Division Multiplexing (WDM) system by using a Coherent Optical Orthogonal Frequency Division Multiplexing (CO-OFDM) with 4-QAM for long haul transmissions of 1800 Km SM. A simulation of 20 WDM channels spaced at 50 GHz, and 20 OFDM signals each with 50 Gbits/s bitrate to produce data rate of 1 Tbits/s is built. The system performance is studied by observing the constellation diagram of the signal and the relationship of BER and OSNR with regard to transmission distance. The results show that the BER increases as the transmission distance increases. Also, as the transmission distance increases, the OSNR needs to be increased to maintain BER in less than 10-3.

Influence of Path Attacks on Security of Six-State Scheme

The safety of the six-state scheme in the practical communication systems was studied based on an effective eavesdropping method, which called path attacks adopted by eavesdroppers. In the practical systems, eavesdropper can select appropriate path to eavesdrop on legitimate users to obtain some information. This method will keep photon number distribution in the laser pulses, and the eavesdropper can be hidden by the losses of quantum channel without being detected. The results show that eavesdropper can get more information with the increase of transmission distance and the average number of photons.

Logarithmic versus modified digital backward propagation algorithm in 224<inline-formula><math display="inline" overflow="scroll"><mrow><mtext> </mtext><mtext> </mtext><mi>Gb</mi><mo>/</mo><mi mathvariant="normal">s</mi></mrow></math></inline-formula> DP-16QAM transmission over dispersion uncompensated fiber links

We have numerically evaluated the transmission performances of digital backward propagation (DBP) algorithms based on the step-size selection methods: (a) constant step-size based modified DBP (M-DBP) and (b) logarithmic step-size based DBP (L-DBP). The nonlinear tolerance of homogeneous dispersion un compensated fiber links are compared in 224 Gb/s DP-16QAM transmission over 656 km of diverse fiber types, i.e., standard single mode fiber (SMF), non-zero dispersion shifted fiber (NZDSF), large effective area pure-silica-core-fiber (LA-PSCF), large effective area fiber, and true wave classic. In the case of homogeneous fiber links, LA-PSCF exhibits higher non linear threshold and gains 32% more transmission distance as compared with SMF by employing M-DBP, while we have observed an additional 13% increase in transmission distance by employing L-DBP.

Phase Noise Influence in Coherent Optical OFDM Systems with RF Pilot Tone: Digital IFFT Multiplexing and FFT Demodulation

We present a comparative study of the influence of dispersion induced phase noise for CO-OFDM systems using Tx channel multiplexing and Rx matched filter (analogue hardware based); and digital FFT multiplexing/ IFFT demultiplexing techniques (software based). An RF carrier pilot tone is used to mitigate the phase noise influence. From the analysis, it appears that the phase noise influence for the two OFDM implementations is very similar. The software based system provides a method for a rigorous evaluation of the phase noise variance caused by Common Phase Error (CPE) and Inter-Carrier Interference (ICI) and this, in turns, leads to a BER specification. Numerical results focus on a CO-OFDM system with 1 GS/s QPSK channel modulation. Worst case BER results are evaluated and compared to the BER of a QPSK system with the same capacity as the OFDM implementation. Results are evaluated as a function of transmission distance, and for the QPSK system the influence of equalization enhanced phase noise (EEPN) is included. For both types of systems, the phase noise variance increases significantly with increasing transmission distance. An important and novel observation is that the two types of systems have very closely the same BER as a function of transmission distance for the same capacity. For the high capacity QPSK implementation, the increase in BER is due to EEPN, whereas for the OFDM approach it is due to the dispersion caused walk-off of the RF pilot tone relative to the OFDM signal channels. For a total capacity of 400 Gbit/s, the transmission distance to have the BER l 10-4 is less than 277 km. For an RF pilot located in the center of the OFDM band in a CO-OFDM implementation with n-level PSK channel modulation the current results suggest that the walk-off effect is equivalent to the EEPN impact in a single channel n-level PSK system with the same capacity. This observation is important for future design of coherent long-range systems since it shows that there is a free choice between CO-OFDM and a high capacity nPSK implementation at least as long as the phase noise influence is concerned.

Phase Noise Influence in Long-range Coherent Optical OFDM Systems with Delay Detection, IFFT Multiplexing and FFT Demodulation

We present a study of the influence of dispersion induced phase noise for CO-OFDM systems using FFT multiplexing/IFFT demultiplexing techniques (software based). The software based system provides a method for a rigorous evaluation of the phase noise variance caused by Common Phase Error (CPE) and Inter-Carrier Interference (ICI) including – for the first time to our knowledge – in explicit form the effect of equalization enhanced phase noise (EEPN). This, in turns, leads to an analytic BER specification. Numerical results focus on a CO-OFDM system with 10–25 GS/s QPSK channel modulation. A worst case constellation configuration is identified for the phase noise influence and the resulting BER is compared to the BER of a conventional single channel QPSK system with the same capacity as the CO-OFDM implementation. Results are evaluated as a function of transmission distance. For both types of systems, the phase noise variance increases significantly with increasing transmission distance. For a total capacity of 400 (1000) Gbit/s, the transmission distance to have the BER < 10−2 for the worst case CO-OFDM design is less than 800 and 460 km, respectively, whereas for a single channel QPSK system it is less than 1400 and 560 km.

光载超宽带脉冲雷达信号传输性能研究

Monocycle pulse and doublet pulse used for ultra-wideband(UWB) pulse radar are generated with dual-parallel Mach-Zehnder modulator(DPMZM).Based on the fadio over fiber(RoF) technology,the transmission performance of the UWB pluses over standard single mode fiber(SSMF) are theoretically analyzed.It is found that monocycle pulse is broadened with the increase of transmission distance,while doublet pulse is firstly compressed and then broadened.Monocycle pulse and doublet pulse with different width satisfying the FCC requirements of UWB pulse radar can be obtained,when the accumulated dispersion of the radar signal is compensated in different degree with dispersion compensation fiber(DCF) after 100 km transmission over SSMF.

Study of orbital angular momentum entangled photons entanglement in atmospheric channel

In this paper, we describe orbital angular momentum entangled photon pair entanglement in atmospheric channel. The Von Karman spectrum of turbulence is used to create a model of two-photon pair entanglement. The effects of atmospheric turbulence on the entanglement of entangled photon pairs of different orbital angular momentum bases are analyzed. The obtained results are as follows because of the presence of atmospheric turbulence, the entanglement of entangled photon pairs decreases with the increase of the propagation distance z in the atmosphere channel. The entanglement of the entangled photon pairs decreases with the increase of transmission distance. The bigger the turbulence intensity, the faster the entanglement decline and the shorter the propagation distanceis. In the same intensity of atmospheric turbulence of the atmospheric channel, the bigger the orbital angular momentum index, the slower the entanglement decline and the further the propagation distanceis.

Analysis of statistical fluctuation in decoy state quantum key distribution system

Decoy state has proven to be a very useful method of significantly enhancing the performance of a quantum key distribution (QKD) system with practical light sources. The data-set size in practical QKD protocol is always finite, which will cause statistical fluctuations. The gain and the error rate of the quantum state are analyzed by considering absolutely statistical fluctuation. The relation between key generation rate and the secure communication distance is shown with exchanged quantum signal (N = 106 -1012) by the method of two-decoy-state protocol under the condition that communication wavelength is 1310 nm (or1550 nm). The result indicates that the minimal number of exchanged quantum signals increases obviously with the increase of transmission distance. The secure transmission distance is 135 km under the condition that quantum signal is 1012.