A Study of Broadband Microwave Fiber Optic Links with Linearized Integrated-Optic Modulators
A universally accepted figure of merit for analog microwave transmission links is the spur-free dynamic range (SFDR), which is the ratio (usually expressed in dB) of the largest to smallest signal a link can transmit and receive without introducing any measurable distortion. This paper presents the result of a study of broadband, microwave fiber optic links that contain high- linearity integrated-optic modulators. This study focused on two distinct modulator forms, the dual-parallel Mach-Zehnder modulator and the linearized directional-coupler modulator. Computer simulations were performed to determine how the SFDR was affected by variations of modulator parameters. In addition, the dynamic range and noise figure of links that included preamplifiers were calculated. The results of the link analysis was that the linearized directional-coupler modulator provided the highest SFDR for a broadband microwave fiber optic link.
© 1994 The International Society for Optical Engineering. SPIE. This work was sponsored in part by the USAF Rome Laboratory, Griffiss AFB, N.Y. under contract no. F30602-91-C-0104. The authors would like to thank G. Tangonan, J. Lam, and R. Hayes of Hughes Research Laboratories, F. Sheehy of Caltech, and N. Bernstein of Rome Laboratory for their helpful comments.
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