Polarization Shift Keying Modulation Research Articles

Polarization-dependent SOA-based PolSK modulation for turbulence-robust FSO communication.

This paper proposes a polarization-dependent semiconductor optical amplifier (SOA)-based polarization shift keying (PolSK) modulation for turbulence-robust free-space optical (FSO) communication. Based on the nonlinear gain and polarization characteristics, the PolSK signal is modulated by the optical bit inversion using the polarization-dependent SOA and linear polarizer (LP). The capability of scintillation mitigation is analyzed under both balanced and polarization-independent SOA-based detections. The proposed technique is evaluated in experiments. The experimental results demonstrated that the bit-error-rate (BER) performance of the proposed technique was close to the conventional Mach-Zehnder modulator (MZM)-based PolSK modulation under various scintillation effects.

Analysis of signal quality in FSO systems with PolSK modulation

In this paper, the quality of the Polarization Shift Keying (PolSK) modulated signal in a Free Space Optical (FSO) system is analyzed. The atmospheric channel is statistically modeled with four different distributions, namely, the Gamma-Gamma distribution, Negative Exponential distribution, Kdistribution, and I-K distribution. For all four channel models, the Average Bit Error Rate (ABER) at the receiving side of the system is determined in an analytically closed form. The results are graphically presented and discussed in order to determine the impact of certain parameters on the ABER, i.e., the quality of the received signal in the PolSK modulated FSO system. These parameters are the Signal-to-Noise Ratio (SNR), the FSO link distance, the wavelength at which the signal is transmitted, and the atmospheric turbulence strength.

Performance analysis of circle polarization shift keying modulation over the exponentiated Weibull distribution

The average bit error rate (BER) and outage probability of circle polarization shift keying (CPOLSK) modulation in free-space optical (FSO) system operating under exponentiated Weibull (EW) distribution are studied. The closed expression of the average BER is derived by generalized Gauss–Laguerre polynomials. The analytical results show the relationship between the average BER and average signal to noise ratio (SNR) of CPOLSK modulation with the effect of aperture averaging under different turbulence strengths and it is compared with on–off keying (OOK) modulation. The relationship between the outage probability and normalized threshold SNR of CPOLSK modulation is studied as well. All the analytical results are verified by the Monte Carlo simulation.

Analysis of beam divergence on free space optical link using polarization shift keying technique

Beam diverging is an indispensable phenomenon on the quality and bit error rate (BER) performance of the free space optical (FSO) communication system. The role of an efficacious modulation technique that mitigates the combined effect of beam diverging and atmospheric attenuation is highly relevant. The weak depolarizing property of the atmosphere advances the use of polarization shift keying (PolSK) modulation. We are subjected to investigate the quality and feasibility of the communication link, considering the impact of beam divergence on the PolSK modulation under various weather conditions. It is shown that PolSK subdues the effects of increase in beam divergence, attenuation factor, and further extends the communication range. A comparison with on off keying and PolSK-based FSO links considering the divergence angle is discussed. Moreover, BER and quality factor graphs are plotted against link distance and beam divergence using PolSK, which improves the performance analysis.

PolSK and ASK Modulation Techniques Based BER Analysis of WDM-FSO System for Under Turbulence Conditions

This paper details a novel model of Wavelength Division Multiplexed (WDM) system using Polarization Shift Keying (PolSK) modulation to increase the capacity of a Free-Space Optical System. The proposed system reduces the cross-channel effects and phase related variations of transmitting signal since PolSK transmits signals in two orthogonal polarized directions. A mathematical model for the system is developed and simulated. The closed-form expressions for the PolSK based WDM system is derived. A case study has been done to implement virtual class rooms in JJCET, Trichy to explore the benefit of using WDM using PolSK for different climatic conditions. The parameters like Bit Error Rate (BER) are analyzed for different weather conditions. The BER of 10−10 is obtained for a link distance of 15.3 km under gamma–gamma turbulence channel in heavy rain conditions, and 5.8 km link distance is achieved for fog conditions using this novel method. Four separate channels each with a data rate of 2.5 Gbps are multiplexed to increase the capacity of the system to 10 Gbps. The system is compared with WDM employing Amplitude Shift Keying under the same environmental conditions. The simulation results obtained for BER and received power against different atmospheric conditions are compared for both the modulation schemes and proved that PolSK based WDM offers better performance.

Single SOA based ultrafast all-optical wavelength conversion for PolSK signal

A novel ultrafast tunable all-optical wavelength conversion for polarization-shift-keying (PolSK) signal based on dual-pump four-wave mixing (FWM), including parallel dual-pump FWM and orthogonal dual-pump FWM, in a single semiconductor optical amplifier (SOA) is proposed. A comprehensive broad-band dynamic model of the all-optical wavelength converter based on parallel dual-pump FWM and orthogonal dual-pump FWM in SOA is developed, for the first time to our knowledge. By numerical simulation, the proposed all-optical wavelength conversion is realized at 40 Gbit/s. The effects of the powers of input waves and wavelength detuning on the conversion efficiency of the wavelength converter are theoretically investigated in detail. The results indicate that, due to using the PolSK modulation format, this scheme is free of pattern effect. In addition, a wide tuning range can be obtained. The proposed all-optical wavelength conversion for PolSK signal is robust and potential for applications in future optical networks in terms of simple implementation and high speed operation.

Simulation research of medium-short distance free-space optical communication with optical amplification based on polarization shift keying modulation

Circular polarization shift keying (CPolSK) modulation technique has many advantages such as excellent BER performance and freedom from the alignment of polarization coordinates of the transmitter and the receiver, etc., and it turns out to be a good choice to FSO system. In this paper, a FSO system using CPolSK modulation is studied by simulation; it is found that the communication performance of the system is excellent in most weather condition. Additionally, three ways of optical signal amplification are proposed, and contrastive analysis on performance of corresponding optical amplification systems is carried out by examining SNR、BER and transmission distance with different specific attenuation. The results show that the system with optical amplifier at the transmitter have the optimum performance, and then the system with optical amplifier at the both ends with the same total gain, it is worst for the system with optical amplifier at the receiver. In addition, the safety factor for high emission power induced by optical amplification is also considered in this paper for practical application. The study above may be utilized in the system design for enhancing performance.

SOA-Based Ultrafast Multifunctional All-Optical Logic Gates With PolSK Modulated Signals

In this paper, we propose a novel scheme for ultrafast multifunctional all-optical logic gates, which can achieve not only simple logic gates including AND, NOR, Smacr 1Smacr2,Smacr1Smacr2,XNOR, and XOR but also complex logic gates including half adder, half subtracter, decoder, and comparer based on four-wave mixing in semiconductor optical amplifiers (SOAs) with polarization-shift-keying (PolSK) modulated signals. A comprehensive polarization-dependent broadband dynamic model of this kind of ultrafast multifunctional all-optical logic gates is presented. By numerical simulation, the multifunctional all-optical logic gates are theoretically realized at 40 Gbit/s. The effects of two input signal powers, injected current, frequency detuning, and polarization dependence of SOA on the output performance of the multifunctional all-optical logic gates are theoretically investigated in detail. The results indicate that this scheme is free of pattern effect due to using the PolSK modulation format. Moreover, the nice eye opening of the logic gates indicates the good performance of the proposed ultrafast multifunctional all-optical logic gates. This scheme is potential for applications in future high bit rate optical networks.

Transceiver Architecture for Incoherent Optical CDMA Networks Based on Polarization Modulation

This paper proposes a novel incoherent transceiver structure for the optical modulation scheme deploying polarization shift keying (Pol-SK) in conjunction with optical code-division multiple-access (OCDMA). The system has been accurately analyzed taking into account the presence of optical amplifier spontaneous emission (ASE) noise, electronic receiver noise, photodiode shot-noise and also multiple access interference (MAI). The application of optical tapped-delay lines in the receiver as the CDMA-decoder has also been investigated. In terms of spreading code, a newly introduced prime code family named as double-padded modified prime code has been utilized. A comprehensive set of results in the literatures showed that the performance of the binary system is approximately 3 dB better than intensity modulations. Therefore, in our following proposed transceiver architecture we have also employed binary Pol-SK modulation. Our results indicate that the proposed architecture consumes less power while enhances the system capacity. Moreover, since the optical beam power is constant, the system has immunity against the self- and cross-phase modulations. Above all, the polarization-based scheme is more promising for very-long-haul high-speed transmissions over the OCDMA networks.

Performance evaluation and assessment of receiver impairments of a novel PolSK transceiver based on differential demodulation

We present a novel transceiver setup for Polarization Shift Keying (PolSK) modulation using a simple transmitter and a receiver based on differential demodulation. The transmitter is made up of a LiNbO(3) phase modulator with the input fiber pigtailed at 45 degrees with respect to the principal axes of the modulator. The receiver is composed of an asymmetric Mach-Zehnder Interferometer (AMZI) and a couple of balanced photodetectors (BPD), as usually employed for receiving DPSK. To our knowledge, it is the first time such receiver structure is applied to PolSK. In order to fully assess the system performance of the proposed setup, we have carried out numerical simulations using a semi-analytical technique for bit-error-rate evaluation and performed experimental measurements at 10 Gbit/s. After having optimized transceiver performances, we evaluated the resilience to receiver impairments to verify the viability of a realistic implementation. Surprisingly, PolSK shows a better sensitivity using a single-end receiver (with the AMZI tuned at the minimum transmittance point) than using a balanced one. Another improvement has been obtained optimizing the driving voltage at the transmitter: this leads to a "non-ideal" PolSK modulation with non-orthogonal symbols, which shows an enhanced performance thanks to a synchronous phase modulation.

WDM-POLSK Transmission Systems by Using Semiconductor Optical Amplifiers

The authors demonstrate the potential of using POLarization Shift Keying (POLSK) modulation format combined with semiconductor optical amplifiers (SOAs) in wavelength division multiplexing (WDM) transmission systems. The constant intensity of the POLSK modulation format allows for substantial removal of cross-gain-modulation impairments in SOAs so that practical amplifier spacing values (more than 100 km) are demonstrated in various different experimental configurations. Record WDM transmission experiments at 10 Gb/s by using SOA-based amplification are presented in short and medium reach system architectures using either single mode fiber or nonzero dispersion shifted fiber