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You searched for subject:(fiber optics links AND subsystems). One record found.

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University of Southern California

1. Bakhtiari, Zahra. All-optical signal processing toward reconfigurable optical networks.

Degree: PhD, Electrical Engineering, 2016, University of Southern California

In the next generation of optical networks, high speed data rates of 100Gb/s per channel or more will be required. In order to include more channels in a single fiber in wavelength division multiplexing (WDM) systems, the channel spacing must be decreased from 200GHz to 50GHz or even smaller. These dense high bit rate WDM systems suffer more severely from the effect of linear and nonlinear degradation in fiber transmission. Phase-modulated format-based WDM systems that have more tolerance for degrading effects, particularly nonlinearity-based degradation have been explored. With growing demand for transmission capacity along with the desire to lower the cost per information bit, spectrally-efficient multilevel modulation format signals such as quadrature amplitude modulation (QAM) have become popular. Higher-order data modulation format signals are quite important to optical communications due to their high spectral efficiency, low electrical baud rate and increased tolerance to fiber-based impairments. Specifically, there is interest in generating quadrature-amplitude-modulation (QAM) signals, and researchers have demonstrated up to 1024-QAM. A laudable goal is the generation of high-order QAM in a tunable fashion such that variable bit rates can be accommodated using optical methods. ❧ In this dissertation, we demonstrate two different techniques for generation of QAM signals. The first method is a polarization-based technique for high speed, tunable QAM signal generation that implements the amplitude control outside the integrated device using a polarizer. The second method is a nonlinearity-based technique that multiplexes initial lower-level modulation format signals at different frequencies into a QAM signal. We also develop fully optical modules to apply various signal processing operations to QAM signals, e.g. demultplexing and information extraction as techniques to avoid coherent receivers in the middle of optical networks. The optical demultiplexing module is based on the phase-sensitive amplification concept, and can demultiplex a QPSK signal into two BPSK sub-channels. We also develop a fully optical module that provides logic/arithmetic relations between symbols carried by a QAM signal. ❧ A disadvantage of higher-order QAM signals is higher sensitivity to noise accumulation, especially in long-haul transmission systems. Amplitude noise not only reduces signal quality but may also be converted into nonlinear phase noise in a transmission line due to the Gordon–Mollenauer effect. Cross-phase modulation in wavelength-division multiplexing (WDM) systems is another cause of amplitude noise to nonlinear phase noise conversion. All-optical regenerators are expected to extend the maximum reach of high-speed transmission systems by eliminating accumulated signal impairments in transmission systems without the need for optical/electronic/optical (O/E/O) conversion. Current phase regeneration schemes are relatively complex and are limited to lower-order modulation formats. Thus, developing all-optical tunable… Advisors/Committee Members: Sawchuk, Alexander A. (Sandy) (Committee Chair), Willner, Alan E. (Committee Member), Armani, Andrea (Committee Member), Haas, Stephan (Committee Member), Molisch, Andreas F. (Committee Member), Jenkins, B. Keith| (Committee Member).

Subjects/Keywords: optical signal processing; coherent systems; nonlinear optics; fiber optics links and subsystems; fiber optics communications

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APA (6th Edition):

Bakhtiari, Z. (2016). All-optical signal processing toward reconfigurable optical networks. (Doctoral Dissertation). University of Southern California. Retrieved from

Chicago Manual of Style (16th Edition):

Bakhtiari, Zahra. “All-optical signal processing toward reconfigurable optical networks.” 2016. Doctoral Dissertation, University of Southern California. Accessed April 18, 2019.

MLA Handbook (7th Edition):

Bakhtiari, Zahra. “All-optical signal processing toward reconfigurable optical networks.” 2016. Web. 18 Apr 2019.


Bakhtiari Z. All-optical signal processing toward reconfigurable optical networks. [Internet] [Doctoral dissertation]. University of Southern California; 2016. [cited 2019 Apr 18]. Available from:

Council of Science Editors:

Bakhtiari Z. All-optical signal processing toward reconfigurable optical networks. [Doctoral Dissertation]. University of Southern California; 2016. Available from: