Nonlinearity induced signal distortions are compensated by processing an input communications signal, in the electrical domain prior to Electrical-to-optical conversion and transmission through an optical link of a communications system. According to the invention, a compensation operator is determined that substantially mitigates the nonlinearity induced signal distortions imparted to an optical signal traversing the communications system. The input communications signal is then input to the compensation operator to generate a predistorted electrical signal. This predistorted electrical signal is then used to modulate an optical source to generate a corresponding predistorted optical signal for transmission through the optical communications system. With this arrangement, arbitrary nonlinearity induced signal distortions imparted by the optical link can be compensated in such a manner that a comparatively undistorted optical signal is obtained at the receiving end of the optical link.

Electrical domain compensation of non-linear effects in an optical communications system

Radio-over-fiber technology provides a simpler pathway for the distribution of wireless signals in broadband wireless networks via optical means. The technology has evolved over the last 30 years, with many challenges already overcome and with many more to address. This paper provides an overview of the technology evolutionary path of RoF with a review of its past, evaluation of its present, and a discussion of its challenges into the future.

Evolution of Radio-Over-Fiber Technology

Read more and get great! That's what the book enPDFd next generation ftth passive optical networks will give for every reader to read this book. This is an on-line book provided in this website. Even this book becomes a choice of someone to read, many in the world also loves it so much. As what we talk, when you read more every page of this next generation ftth passive optical networks, what you will obtain is something great.

Next-Generation FTTH Passive Optical Networks

We propose and demonstrate a novel and simple predistortion circuit using reflective antiparallel diodes for linearization of electro-absorption modulators (EAMs) in multiband orthogonal frequency-division multiplexing (MB-OFDM) ultra-wideband (UWB) radio-over-fiber systems for UWB signals from 3.1 to 4.8 GHz. In this novel predistortion circuit, neither amplifiers, nor phase shifters are used, while only two antiparallel connected diodes are used, and the predistortion signal is adjusted by tuning the diodes' dc-bias current. The simple architecture makes the circuit cost effective and suitable for UWB system applications. By adding the predistortion circuit before the EAM, more than 7-dB suppression in third-order intermodulation distortion and 11-dB improvement in spurious-free dynamic range are achieved over the frequency range of 3.1-4.8 GHz, i.e., bandgroup 1 of MB-OFDM UWB. Correspondingly, 1-dB improvement in error vector magnitude is obtained experimentally when the designed predistortion circuit is used.

A Novel Analog Broadband RF Predistortion Circuit to Linearize Electro-Absorption Modulators in Multiband OFDM Radio-Over-Fiber Systems

Optical dispersion imposed on a communications signal conveyed through an optical communications system is compensated by modulating the communications signal in the electrical domain. A compensation function is determined that substantially mitigates the chromatic dispersion. The communications signal is then modulated in the electrical domain using the compensation function. In preferred embodiments, compensation is implemented in the transmitter, using a look-up-table and digital-to-analog converter to generate an electrical predistorted signal. The electrical predistorted signal is then used to modulate an optical source to generate a corresponding predistorted optical signal for transmission through the optical communications system.

Optical dispersion compensation in the electrical domain in an optical communications system

A novel technique to improve an analog optical transmission performance by reducing both the nonlinearity and chromatic dispersion induced carrier suppression has been proposed. The intrinsic nonlinear distortion component of Mach-Zehnder modulator (MZM) was reduced by gain saturation characteristics of semiconductor optical amplifier (SOA). The composite triple beat (CTB) of MZM was reduced as much as 9 dB at the quadratic bias point and the following enhancement of dynamic range by 4.5 dB was obtained. The RF carrier suppression for the transmission length and operating frequency was reduced by a negative chirp characteristic of semiconductor optical amplifier (SOA) and the enhancement of CTB after transmission were also achieved as a result of the linearization using SOA.

Mitigation of dispersion-induced effects using SOA in analog optical transmission

An optical single sideband (OSSB) generation method using phase modulation in semiconductor optical amplifier (SOA) is proposed to overcome the dispersion-induced carrier suppression problem which limits available fiber frequency range in analog optical link. The OSSB generation was achieved by phase variation in SOA which results /spl pi//2 phase difference between the amplitude and phase terms of modulated optical signal. A 21-dB difference between two sidebands was experimentally observed. From the transmission experiment up to 100 km over single-mode fiber, we confirmed that the generated OSSB signal is good enough to remove the radio frequency signal degradation due to chromatic dispersion.

Optical single sideband signal generation using phase modulation of semiconductor optical amplifier

Anoellinearizationmethodisproposedtoincreasethedynamicrangeofanelectro-absorptionmodulatorinsubocta eband - width operation by exploiting the fact that the phase of third-orderintermodulationdistortion arieswiththedcbias oltage.Areductionof14dBinIMD3andasubsequentincreaseofthelineardynamicrangewere experimentallyobtained. 2001 John Wiley & Sons, Inc. Mi-crowave Opt Technol Lett 29:2 5, 2001. Key words: electroabsorptionmodulator;dual-parallelmodulation;linearization;intermodulationdistortion IMD ; lineardynamicrange() 1.INTRODUCTION Recently, owing to an increase of mobile telecommunicationsubscribers and demands on a variety of high-quality services,the trend toward RF carrier frequency shows an increase tothe mm-wave frequency range. Related to this, an analogoptical link with an extremely large bandwidth and low trans-mission loss has received attention as an efﬁcient RF signaltransmission link, both in wired and wireless communicationsystems. These links require a high linearity and a largedynamic range for better performance. However, direct mod-ulation of a laser diode presents the problem of chirping,which limits high-frequency operation. So, a low-chirp high-speed external optical modulator needs to be used in spite ofits inherent nonlinearity. An LiNbO intensity modulator and

Nonlinearity suppression of electroabsorption modulator through dual-parallel modulation

A novel method to suppress nonlinear distortion of directly modulated laser diodes using a dual parallel modulation scheme has been proposed. The scheme exploits the fact that frequency chirping influences the phase of RF signals. Two properly controlled undesired intermodulation signals with out-of-phase difference are cancelled via coherent RF recombination at the photodetector. The validity of this scheme was confirmed through experiments. A 20-dB reduction of the third-order intermodulation distortion was achieved and tunability of the suppression region was observed.

Nonlinear distortion suppression in directly modulated DFB-LD by dual-parallel modulation

A novel linearization process in an electroabsorption-modulated laser (EML) is proposed and experimentally demonstrated. A dual-parallel modulation scheme is used to compensate the nonlinear component of the EML by controlling the dc bias voltages of each EML separately. The validity of the proposed modulation scheme is confirmed through simulations and experiments. From a dual-parallel modulation experiment at 8 GHz, a reduction of 23 dB in IMD3 and a following increase of linear dynamic range of 19.6 dB are achieved compared to those of a single EML operation.

https://www.researchgate.net/profile/Sang_Kook_Han/publication/3291018_Linearity_enhancement_of_an_electroabsorption_modulated_laser_by_dual-parallel_modulation/links/54af6fec0cf2b48e8ed66588.pdf

Hyun-Do Jung

Papers

Mitigation of dispersion-induced effects using SOA in analog optical transmission

Optical single sideband signal generation using phase modulation of semiconductor optical amplifier

Nonlinearity suppression of electroabsorption modulator through dual-parallel modulation

Nonlinear distortion suppression in directly modulated DFB-LD by dual-parallel modulation

Linearity enhancement of an electroabsorption modulated laser by dual-parallel modulation