Dispersion Penalty Research Articles

Chromatic dispersion penalty by angular coupling between resonant cavity light-emitting diode and plastic optical fibre

Chromatic dispersion penalty by angular coupling between a resonant cavity light-emitting diode (RCLED) and a plastic optical fibre is presented. To evaluate the influence of the angular-dependent spectral characteristics of the RCLED on the chromatic dispersion penalty, the effective spectral linewidth of the RCLED was defined and the bit error rate performances for 500 Mbit/s by 50 m transmission were calculated. The calculated results were in good agreement with the experimental ones that showed the chromatic dispersion penalty of 1.2 dB at BER 10 -12 in the angle of 26deg.

Single-side-band optical modulation in SCM systems for high-speed optical transmission

In order to decrease dispersion penalty and increase the optical bandwidth efficiency, an optical single-side-band modulation (SSBM) scheme in sub-carrier multiplexing (SCM) is proposed. The principle of the SSBM is analytically presented, and a configuration for generating optical SSB signal is proposed using a balanced Mach-Zehnder electro-optic modulator.

Dispersion penalty analysis using light injection method in the feedforward optical transmitter for WDM/SCM radio-over-fiber systems

We have experimentally and theoretically demonstrated the transmission performance of a feedforward optical transmitter using an external light injection technique. The feedforward compensation method shows 31 dB intermodulation distortion suppression and 2.2 dB noise reduction. The feedforward architecture used a wavelength-locked Fabry–Perot laser diode whose side-mode suppression ratio about 35 dB over a 12-nm range. The suppression characteristics of the intermodulation distortion for various wavelength differences and transmission lengths were measured and analyzed as the evaluation criteria for the system performance in WDM/SCM based radio-over-fiber systems.

A WDM-PON with a 40 Gb/s (32 × 125 Gb/s) capacity based on wavelength-locked Fabry-Perot laser diodes

We investigate a high capacity WDM-PON based on wavelength locked Fabry-Perot laser diodes. An error-free transmission of 1.25 Gb/s per subscriber was achieved with a flat-top passband AWG and a laser diode with low reflectivity. Then, we demonstrate a WDM-PON of 40-Gb/s capacity of 32 channels over 15 km of single mode fiber. It also shows that color-free operation within conventional C-band wavelength. The observed dispersion penalty after 30 km transmission was 0.5 dB. The demonstrated WDM-PON shows a robust transmission performance on the optical back reflection.

Potential of the polymer optical fibers deployed in a 10Gbps small office/home office network

We have performed a detailed study of four Perfluorinated Graded Index Polymer Optical Fiber (50/490, 62.5/490 and 120/490) issued from several manufacturers and designed to be used in short length (100m) small office/home office network operating at 850nm. We have used commercially available 850nm low cost XFP transceivers and have compared the power dispersion penalties measurements with the ones realized using a photoreceiver including the Electronic Dispersion Compensation technology to increase the range of the transmission without impairments. It will be demonstrated the potential of the polymer fibers coupled to the electronic dispersion compensation technology to successfully transmit a 10GBase-SR signal with a Bit Error Rate of 10(-12) over 100m.

A 240 km Reach DWDM-PON of 8-Gb/s Capacity using an Optical Amplifier

We demonstrate a 240 km reach DWDM-PON at 8-Gb/s capacity based on wavelength-locked Fabry-Perot laser diodes and a bidirectional EDFA. We achieve a packet-error-free transmission in both the 64 upstream and 64 downstream channels, guaranteeing a 125 Mb/s symmetric data rate per user. There is no noticeable dispersion penalty. The power penalty due to the crosstalk induced by the DWDM transmission and detuning between AWGs is less than 1.2 dB, when the detuning is within ${\pm}0.12 nm$ .

Two-Dimensional Spatio-Temporal Signal Processing for Dispersion Compensation in Time-Stretched ADC

Time-stretched analog-to-digital converters (ADCs) have offered revolutionary enhancements in the performance of electronic converters by reducing the signal bandwidth prior to digitization. An inherent limitation of the time-stretched ADC is the frequency-selective response of the optical system that reduces the effective number of bits for ultrawideband signals. This paper proposes a solution based on spatio-temporal digital processing. The digital algorithm exploits the optical phase diversity to create a flat RF frequency response, even when the system's transfer function included deep nulls within the signal spectrum. For a 10times time-stretch factor with a 10-GHz input signal, simulations show that the proposed solution increases the overall achievable signal-to-noise-and-distortion ratio to 52 dB in the presence of linear distortions. The proposed filter can be used to mitigate the dispersion penalty in other fiber optic applications as well.

Dispersion tolerance of coherent WDM

We present the transmission of a 298.2-Gb/s copolarized coherent wavelength-division-multiplexing system over 80 km of standard single-mode fiber, achieving an information spectral density of 1 b/s/Hz with no prefilters at the transmitter. Odd and even tributary channels were encoded with data and delayed-data-bar pseudorandom binary sequence 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> -1 patterns. The dispersion tolerance is investigated, and the dispersion penalty of this system is improved through adjustment of the relative phase of adjacent channels. Under optimum conditions, the dispersion penalty could be reduced from over 3 dB to less than 1 dB

Dispersion penalty analysis for VSR —1 optical links

This paper presents and approach to calculate dispersion penalty for VSR-1 optical links. Based on parameters of a specific VSR-1 link, dispersion penalties are computed for various modal dispersion bandwidths respectively. The worst-case eye closure is expressed numerically by using the signal waveform at time 0, and the signal waveform is obtained in frequency domain through FFT algorithm. By this approach, the dispersion penalty is determined by the shape of transfer functions of the various components in the links. To simplify the derivation of multimode fiber link transfer function, a Gaussian form of normalized impulse response is used. This calculation approach can be used to estimate the worst-case dispersion penalty of VSR-1 links in the link budget analysis.

The Impact of Dispersion Penalty and Device Losses on the Performance of Fiber-optic CDMA Systems

Fiber-optic code division multiple access (FO-CDMA) system configuration is introduced. The device losses of active fiber connector, optical encoder/decoder, star coupler, transmission media, power penalty induced by fiber dispersion and the chirp effect of laser source are analyzed. Theoretical analysis of system bit error rate (BER) is achieved. Numerical results show that, dispersion power penalty makes system BER decline. The chirp effect of laser source can compensate for the dispersion power penalty for short transmission distance. For a FO-CDMA system with 20 active users, optical orthogonal code with weight 4 is users' address codes, and the distance between transmitter and receiver is 30 km, if BER is 10 -9 , then the transmitted power requires 4.4 dBm for normal single mode fiber (SMF) and 0.7 dBm for dispersion shift fiber (DSF). The system total loss is 44.9 dB for normal SMF and 41.2 dB for DSF.

Uncooled performance of 10-Gb/s laser modules with InGaAlAs-InP and InGaAsP-InP MQW electroabsorption Modulators integrated with semiconductor amplifiers

Uncooled operation of long-reach high performance C-band 10 Gb/s of optical modulator modules is presented. Modules consisting of a distributed feedback laser and a chip with a monolithically integrated electroabsorption modulator and semiconductor optical amplifier based on multiquantum-well structures of both InGaAsP-InP and InGaAlAs-InP material systems are presented. Dispersion penalty of 1 dB over 94-km transmission, output power above 0 dBm, and low extinction ratio variation are demonstrated over an 80/spl deg/C temperature range. A simple analysis of the quantum confined Stark effect is employed to explain the temperature-dc bias voltage dependence.

Performance evaluation of N × 40 Gbps CS-RZ and DCS-RZ modulated signals transmitted over single mode fiber based on non-ideal LiNbO3 Mach-Zehnder modulators

We investigate the transmission performance of N × 40 Gbps carrier-suppressed return-to-zero (CS-RZ) and duobinary CS-RZ (DCS-RZ) modulated wavelength division multiplexed (WDM) signals over the standard single-mode fiber (SSMF) based on non-ideal Mach-Zehnder (MZ) modulators through numerical simulations. In addition to that, the impact on receiver margin related to the residual chirp due to an asymmetry ratio of modulators as well as the effect of the applied chirp of modulators has been studied. As the asymmetry ratio of modulators is increased, dispersion penalties are increased asymmetrically at around the zero dispersion wavelength for the CS-RZ format. The DCS-RZ modulation format has a symmetric behavior due to different characteristics of the residual chirp of modulators. The receiver margin for the DCS-RZ modulation format is larger than the CS-RZ modulation format above the asymmetry ratio of 0.82 of modulators (extinction ratio of 20 dB) with the optimal ΔλDCF. By controlling the negative/positive applied chirp of the first/second modulator, dispersion penalties can be reduced for both the CS-RZ and DCS-RZ formats. In the DCS-RZ format compared to the CS-RZ format, the effect of the applied chirp of the first modulator is more dominant than that of the second modulator. The simulation results show that the receiver margin is limited by the asymmetry ratio of modulators as well as a deviated wavelength from the zero dispersion wavelength of dispersion compensating fibers (DCF) in order to be fully post-compensated. Dispersion penalties can be reduced with appropriate chirp parameters of two non-ideal modulators.

Chromatic Dispersion Tolerance of the SSB-Modulated Signals

It is shown that the SSB modulated signal has smaller chromatic-dispersion induced penalty than the DSB modulated signal only when the accumulated dispersion is large. When the accumulated dispersion is small, the SSB modulated signal has larger dispersion penalty than the DSB modulated signal. Therefore, if one builds a system with very low dispersion penalty, SSB modulation may end up with a larger dispersion penalty.

Impact of fiber nonlinearity on PMD penalty in DWDM transmission systems

Polarization-mode dispersion (PMD) penalty measurement on a 10-Gb/s deployment-ready dense wavelength-division-multiplexing (DWDM) long-haul transmission system is reported in this letter. We investigate the impact of self-phase modulation (SPM) and cross-phase modulation (XPM) on PMD penalty in the DWDM system. It is confirmed that SPM can suppress the PMD penalty, and XPM-induced polarization-scattering in DWDM systems can reduce the PMD impairment a little bit further. Our measurements suggest that it is necessary to carry out the PMD penalty test on DWDM systems rather than back-to-back systems in order to accurately allocate transmission margin of the systems.

Bidirectional WDM PON Using Light-Emitting Diodes Spectrum-Sliced With Cyclic Arrayed-Waveguide Grating

We proposed and demonstrated a bidirectional wavelength-division-multiplexing passive optical network by using spectrum-sliced light-emitting diodes (LEDs) with cyclic arrayed-waveguide gratings (AWGs). When the spectrum-slicing technique is used, it is often difficult to secure an adequate amount of system margin due to the large slicing loss and low output power of LED. To overcome this problem, we reduced the slicing loss by using all the peaks of the spectrum-sliced light (separated by the free-spectral range of AWG) and improved the receiver sensitivity by using the forward-error correction technique. The excessive dispersion penalty (caused by using multiple peaks) was suppressed by using a simple dispersion precompensation circuit.

PMD Penalty Monitor for Automatic PMD Compensation of 40-Gb/s RZ Data

A dual-window spectral analysis polarization-mode dispersion (PMD) penalty monitor of novel design for 40-Gb/s return-to-zero signals is presented. Its good performance was verified in a PMD compensation experiment using an electrooptical Ti : LiNbO/sub 3/ distributed compensator.

High performance uncooled C-band, 10 Gbit/s InGaAlAs MQW electroabsorption modulator integrated to semiconductor amplifier in laser-integrated modules

Long reach C-band 10 Gbit/s uncooled operation of laser integrated to InGaAlAs electroabsorption modulator packages is presented. Using a design employing InGaAlsAs multi-quantum wells (MQW), uncooled operation over an 80°C temperature range, with modulated output power in excess of 0 dBm, 1.7 dB maximum change in extinction ratio, and with a dispersion penalty of 1 dB for 1600 ps/nm propagation is demonstrated.

Correlation between dispersion penalty and time-resolved chirp for an integrated widely tunable electroabsorption-modulated SGDBR laser across the EDFA gain bandwidth

We report, for the first time, the experimental relationship between time-resolved chirp and dispersion penalty across the 30-nm tuning range of a sampled-grating distributed Bragg reflector semiconductor-optical-amplifier electroabsorption-modulator laser. The extinction ratio, time-resolved chirp, and dispersion power penalties at transmission distances of 200, 275, and 350 km are presented for various values of effective alpha. Finally, a suitable method of computing the effective alpha from time-resolved spectroscopy is also presented.

Optical single-sideband modulator for broad-band subcarrier multiplexing systems

We experimentally demonstrate an enhanced optical single-sideband (OSSB) modulator for subcarrier-multiplexing (SCM) systems that provides improvement of the output optical modulation depth without increasing either the second-order or the third-order nonlinear distortion of the transmitted radio frequency signal. The modulator is deployed in an SCM link conveying 4 /spl times/ 622-Mb/s modulated subcarriers, demonstrating an enhancement of five orders of magnitude in bit error rate compared to the use of a dual-electrode OSSB modulator design. In addition, the dispersion penalty for the worst-case channel is reduced to less than 1.7 dB.

Power penalties due to in-band and out-of-band dispersion in FBG cascades

We measure the in-band dispersion penalty in a cascade of five 50-GHz low-dispersion linear-phase fiber Bragg gratings (FBGs) and compare the results with conventional apodised FBGs. At the 0.5-dB power penalty level, the usable bandwidth of a single linear-phase FBG (40 GHz) is twice as wide as that of a conventional apodised FBG (19 GHz). The bandwidth-utilization factor of a single linear-dispersion grating is 89%, while for the five-grating cascade, it is 76%. To our knowledge, these are the highest values reported to date for cascaded optical devices. The corresponding factors for the conventional gratings are 53% and 31%. We also measure the additional penalty on a dropped channel caused by a cascade of five adjacent-channel gratings. The bandwidth narrowing due to the adjacent-channel FBGs is 6 GHz both for linear-phase and conventional FBGs, giving a usable bandwidth of 34 GHz (linear-phase) and 13 GHz (conventional).