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2 December 1992 Linewidth-insensitive coherent optical analog links
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Coherent optical analog links offer several important advantages over conventional direct detection links including the ability to separate wavelength-division multiplexed signals, frequency translation, and utilization of angle modulation formats. However, the wide linewidth of semiconductor lasers can cause substantial performance degradation of these links. This paper analyzes the signal-to-noise ratio and the dynamic range of amplitude modulated (AM) and frequency modulated (FM) coherent links, and compares them to direct detection links. It is concluded that a properly designed AM system is insensitive to laser linewidth. For optical powers less than 1mW, the performance of coherent AM links is better than that of direct detection links; for optical powers greater than 1mW, the performance of the two links is nearly the same. Coherent FM links have the potential to increase the SNR and the dynamic range by more than 10 dB as compared to direct detection and coherent AM links. However, FM links are potentially sensitive to laser linewidth, and require elaborate phase noise cancellation techniques when semiconductor lasers are used.
© (1992) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Delfin Jay M. Sabido, Thomas K. Fong, Robert F. Kalman, and Leonid G. Kazovsky "Linewidth-insensitive coherent optical analog links", Proc. SPIE 1703, Optical Technology for Microwave Applications VI and Optoelectronic Signal Processing for Phased-Array Antennas III, (2 December 1992);

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