This paper sets the ultimate limit on the maximum amount of optical data pulses that can be sent through a single fiber in a given period under the wavelength-division-multiplexed (WDM) format. The discovery in 1973 that optical soliton on a single wavelength beam can exist in fiber is one of the most significant events since the perfection of low-loss optical fiber communication. This means that, in principle, data pulses may be transmitted in a fiber without degradation forever. This soliton discovery sets the ultimate goal for optical fiber communication on a single-wavelength beam. Another most significant event is the development of WDM transmission in a single-mode fiber. This means that multiple beams of different wavelengths, each carrying its own data load, can propagate simultaneously in a single-mode fiber. This WDM technique provides dramatic increase in the bandwidth of a fiber. However, due to the presence of complex nonlinear co-propagating pulses on different wavelength beams, it is no longer certain that WDM soliton can exist. The existence of solitons is a blissful event in nature. It is a marvel that the delicate balance between the dispersion effect and the nonlinear effect can allow a specially shaped optical pulse to propagate in the fiber without degradation. They occur only on single-wavelength beams. When beams with different wavelengths co-propagate in a single-mode fiber, such as in the WDM case, interaction of pulses on different beams via the nonlinear cross-phase-modulation (CPM) effect (the Kerr effect) is usually instrumental in destroying the integrity of solitons on these wavelength multiplexed beams. This paper shows that temporal solitons can exist on WDM beams in a single fiber under appropriate conditions. The existence of these solitons critically depends on the presence of the nonlinear CPM effect of the WDM beams. Just as the earlier single-beam soliton case, this discovery sets the ultimate goal for optical fiber communication on WDM beams.
This work was done by Cavour Yeh and Larry Bergman of Caltech for NASA's Jet Propulsion Laboratory. To obtain a copy of the report, "The Existence of Optical Solitons on Wavelength Division Multiplexed Beams in a Nonlinear Fiber," access the Technical Support Package (TSP) free on-line at www.nasatech.com/tsp the Physical Sciences category.
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Refer to NPO-20772, volume and number of this NASA Tech Briefs issue, and the page number.
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Solitons on WDM Beams in a Nonlinear Optical Fiber
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Overview
The document presents significant advancements in optical fiber communication, particularly focusing on the existence of solitons in wavelength division multiplexed (WDM) beams within single-mode fibers. It highlights the groundbreaking discovery that fundamental optical solitons can propagate undistorted over long distances when specific conditions regarding their amplitudes and shapes are met. This finding is crucial for enhancing the efficiency and capacity of optical fiber communication systems.
The report outlines the evolution of optical communication, beginning with the discovery of optical solitons on single wavelength beams in 1973, which marked a pivotal moment in the development of low-loss optical fiber technology. This discovery indicated that data pulses could theoretically be transmitted indefinitely without degradation, setting a high standard for future advancements.
Wavelength division multiplexing (WDM) is introduced as a technique that allows multiple beams of different wavelengths to carry distinct data loads simultaneously through a single fiber, significantly increasing the fiber's bandwidth. However, the document notes that the complex nonlinear interactions between co-propagating pulses on different wavelengths raised concerns about the viability of WDM solitons.
The authors present a solution by demonstrating that WDM solitons can indeed exist when the amplitudes of the co-propagating pulses are properly adjusted. The existence of these solitons relies on the nonlinear cross-phase modulation effect among the WDM beams, which is essential for maintaining the delicate balance between dispersion and nonlinearity that allows specially shaped optical pulses to propagate without degradation.
The document emphasizes the potential of this technology to enable the transmission of multi-terabits of information through a single fiber in a bit-parallel WDM format, paving the way for future developments in high-capacity optical communication systems. The research was conducted at the Jet Propulsion Laboratory and sponsored by the National Aeronautics and Space Administration, underscoring its significance in advancing communication technologies.
In summary, this report encapsulates a pivotal moment in optical fiber communication, detailing the discovery of solitons in WDM systems and their implications for future data transmission capabilities, ultimately setting the stage for a new era in high-speed communication.
