Chromatic dispersion limitations for FSK and DPSK systems with direct detection receivers

Chromatic dispersion limitations for frequency-shift keying (FSK) and differential phase-shift keying (DPSK) systems using narrow-linewidth lasers and direct-detection receivers are discussed. The limitations are found to depend strongly on the receiver configuration. The receiver must include an optical frequency discriminator, such as a Mach-Zehnder interferometer, and either a balanced photodetector pair or a single photodetector at the interferometer output. For transmission at 1550 nm over 1310-nm optimized single-mode fiber, the distance for 1-dB eye closure penalty at 10 Gb/s ranges from 20 to 70 km, depending on the modulation format and the receiver configuration.<
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