Eye Diagram

The wireless telecommunication system of hybrid free-space optics (FSO) utilizes a transmission medium of free space to transmit data at high bit rates. However, it is exposed to various effects of noise in different weather conditions. This paper studies compensation for atmospheric turbulence and modal dispersion in optical communication systems. An investigation is carried out of 12-channel Spatial Division Multiplexing (SDM) over FSO link under different weather conditions and few-mode fiber (FMF) based on linear Bessel filter. The experiments show that the system capacity increases effectively by using SDM over hybrid FSO- fiber to the home (FTTH) that operate at 1550 nm wavelength. A series of simulation experiments

The wireless telecommunication system of hybrid free-space optics (FSO) utilizes a transmission medium of free space to transmit data at high bit rates. However, it is exposed to various effects of noise in different weather conditions. This paper studies compensation for atmospheric turbulence and modal dispersion in optical communication systems. An investigation is carried out of 12-channel Spatial Division Multiplexing (SDM) over FSO link under different weather conditions and few-mode fiber (FMF) based on linear Bessel filter. The experiments show that the system capacity increases effectively by using SDM over hybrid FSO- fiber to the home (FTTH) that operate at 1550 nm wavelength. A series of simulation experiments

Chromatic dispersion is very serious issue for communication engineers while designing a wave division multiplexing for optical communication. In the present scenario there is a increasing demand of high speed internet which require more capacity and more bandwidth. The effect of chromatic dispersion can be reduced by compensation technique. [1, 2] The chromatic dispersion also has inverse relationship with FWM. In this paper we used post dispersion compensation along with the fiber Bragg grating to reduce the effect of chromatic dispersion. Also we can compare the Bit error rate at different power levels 5 db, 10 db and 20 db while the length of fiber is fixed. After simulation it is proven that bit error rate is a function of input power level. The pulse broadening is a function of length of fiber which has been shown in this work When the BER increases quality factor decreases and overall fiber optic system degraded. In this paper we also prove that the BER is also a function of Length of Fiber. As the fiber length increases BER also increases. The whole simulationn is performed by Optisystem simulation software. Also by examine the eye diagram it is clear that link performance is improved by using dispersion compensation.

A return-to-zero differential quadrature phase-shift keying (DQPSK) modulation scheme is proposed for all-optical orthogonal frequency-division multiplexing transmission systems. The system uses coupler-based inverse fast Fourier transform/fast Fourier transform to support a 700 km single-mode fiber link and a transmission rate of 40 Gb∕s without any nonlinear compensation. The performance of the proposed system is evaluated using simulation and four performance measures are obtained, namely, the eye diagram, the eyeopening penalty (EOP), the power spectral broadening, and the bit error rate (BER). The effect of self-phase modulation is taken into account in the performance evaluation. In addition, the performance of the proposed system is compared to that of a traditional one adopting a non-return-to-zero DQPSK scheme. Our results reveal that the proposed system outperforms the traditional one in all four aforementioned performance measures, yet the spectral efficiency is almost preserved. Specifically, for an input average power of 12 dBm, a reduction in both the required optical-signal-to-noise ratio of about 4 dB (to achieve a BER of 10 −6 ) and the EOP of about 5 dB are reported when adopting the proposed system, as compared to the traditional one.

In the modern day industries, Fiber optic transmission and communication are technologies that are
constantly growing and support more challenges. Three properties of optical fibers are dispersion,
absorption and scattering which cause attenuation and also decreased in transmitted power. To combat
these losses and improve the reliability of fibers introduced many advanced technologies. Here two
compensation techniques such as Fiber Bragg Grating and Optical Phase Conjugation are discussed with
the help of simulation software “OPTSIM” to compensate dispersion. We have also analyzed the time
delay of the received signal with variation of frequency by using B4530 trainer in the “Telecommunication
Lab, Rajshahi University of Engineering & Technology, Bangladesh” and proved that when frequency of
the transmitted signal increases then time delay i.e. dispersion of the received signal decreases.

This paper presents a 20 Gb/s injection-locked clock and data recovery (CDR) circuit for burst mode applications. Utilizing a half rate injection-locked oscillator (ILO) in the proposed CDR circuit leads to higher speed operation and lower power consumption. In addition, to accommodate process, voltage, and temperature (PVT) variations and to increase the lock range, a frequency locked loop is proposed to use in this circuit. The circuit is designed in 0.18 µm CMOS and the simulations for 2 7-1 pseudo random bit sequence (PRBS) show that the circuit consumes 55.3 mW at 20 Gb/s, while the recovered clock rms jitter is 1.1 ps.

A return-to-zero differential quadrature phase-shift keying (DQPSK) modulation scheme is proposed for all-optical orthogonal frequency-division multiplexing transmission systems. The system uses coupler-based inverse fast Fourier transform/fast Fourier transform to support a 700 km single-mode fiber link and a transmission rate of 40 Gb∕s without any nonlinear compensation. The performance of the proposed system is evaluated using simulation and four performance measures are obtained, namely, the eye diagram, the eyeopening penalty (EOP), the power spectral broadening, and the bit error rate (BER). The effect of self-phase modulation is taken into account in the performance evaluation. In addition, the performance of the proposed system is compared to that of a traditional one adopting a non-return-to-zero DQPSK scheme. Our results reveal that the proposed system outperforms the traditional one in all four aforementioned performance measures, yet the spectral efficiency is almost preserved. Specifically, for an input average power of 12 dBm, a reduction in both the required optical-signal-to-noise ratio of about 4 dB (to achieve a BER of 10 −6 ) and the EOP of about 5 dB are reported when adopting the proposed system, as compared to the traditional one.

In this work, the transmission performance of a directly modulated 1.5 μm Vertical Cavity Surface Emitting Laser (VCSEL) are investigated with respect to the shape of the driving electrical pulse. A model is developed for the device used and the transmission over standard Single Mode Fiber is simulated for NRZ and RZ formats, at 2.5 Gb/s and 10 Gb/s. Results are reported for propagation lengths between 10 Km and 30 Km. Simulations results are compared with experiments. We found that Q factor and propagation length can be improved if non Gaussian pulses are employed.

The main objective of this paper is to design and performance analyses of 16 users OCDMA (optical code division multiple access) encoding system using ultrashort pulses. In optical code division multiple access system, many users share the same transmission medium by assigning unique pseudo-random optical code (PRBS) to each user. O-CDMA systems results to indicate the significant improvement in term of Bit Error Rate (BER) and very high quality factor are in the form of Q-value. Thus the simulations are done in OPTSIM Rsoft tool. In this Optsim to generate the ultrashort pulses using with and without compression techniques.

A return-to-zero differential quadrature phase-shift keying (DQPSK) modulation scheme is proposed for all-optical orthogonal frequency-division multiplexing transmission systems. The system uses coupler-based inverse fast Fourier transform/fast Fourier transform to support a 700 km single-mode fiber link and a transmission rate of 40 Gb∕s without any nonlinear compensation. The performance of the proposed system is evaluated using simulation and four performance measures are obtained, namely, the eye diagram, the eyeopening penalty (EOP), the power spectral broadening, and the bit error rate (BER). The effect of self-phase modulation is taken into account in the performance evaluation. In addition, the performance of the proposed system is compared to that of a traditional one adopting a non-return-to-zero DQPSK scheme. Our results reveal that the proposed system outperforms the traditional one in all four aforementioned performance measures, yet the spectral efficiency is almost preserved. Specifically, for an input average power of 12 dBm, a reduction in both the required optical-signal-to-noise ratio of about 4 dB (to achieve a BER of 10 −6 ) and the EOP of about 5 dB are reported when adopting the proposed system, as compared to the traditional one.