Effects of chromatic dispersion on optical coherent-detection systems

Ho, Keang-Po; Wang, Hsi-Cheng

doi:10.1109/tcomm.2008.060432

Cited by 5 publications

(4 citation statements)

References 12 publications

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“…Such impairments result not only from group-velocity dispersion (GVD) governed by the parameter D but also from polarization-mode dispersion (PMD) governed by the parameter D p . As expected, both of them affect the performance of coherent and self-coherent systems, although their impact depends on the modulation format employed and is often less severe compared with that for IM/DD systems [76]- [83]. The reason is easily understood by noting that coherent systems, by necessity, use a semiconductor laser operating in a single longitudinal mode with a narrow linewidth.…”

Section: Fiber Dispersionmentioning

confidence: 88%

Advanced Lightwave Systems

Agrawal¹

2010

Fiber‐Optic Communication Systems

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Lightwave systems discussed so far are based on a simple digital modulation scheme in which an electrical binary bit stream modulates the intensity of an optical carrier inside an optical transmitter (on-off keying or OOK). The resulting optical signal, after its transmission through the fiber link, falls directly on an optical receiver that converts it to the original digital signal in the electrical domain. Such a scheme is referred to as intensity modulation with direct detection (IM/DD). Many alternative schemes, well known in the context of radio and microwave communication systems [l]-[3], transmit information by modulating both the amplitude and the phase of a carrier wave. Although the use of such modulation formats for optical systems was considered in the 1980s [4]-[9], it was only after the year 2000 that phase modulation of optical carriers attracted renewed attention, motivated mainly by its potential for improving the spectral efficiency of WDM systems [10]- [16]. Depending on the receiver design, such systems can be classified into two categories. In coherent lightwave systems [14], transmitted signal is detected using homodyne or heterodyne detection requiring a local oscillator. In the so-called self-coherent systems [16], the received signal is first processed optically to transfer phase information into intensity modulations and then sent to a direct-detection receiver.The motivation behind using phase encoding is two-fold. First, the sensitivity of optical receivers can be improved with a suitable design compared with that of direct detection. Second, phase-based modulation techniques allow a more efficient use of fiber bandwidth by increasing the spectral efficiency of WDM systems. This chapter pays attention to both aspects. Section 10.1 introduces new modulation formats and the transmitter and receiver designs used to implement them. Section 10.2 focuses on demodulation techniques employed at the receiver end. The bit-error rate (BER) is considered in Section 10.3 for various modulation formats and demodulation schemes. Section 10.4 focuses on the degradation of receiver sensitivity through mechanisms such as phase noise, intensity noise, polarization mismatch, and fiber dispersion. Nonlinear phase noise is discussed in Section 10.5 together with the techniques used for its compensation. Section 10.6 reviews the recent progress realized with emphasis on improvements in the spectral efficiency. The topic of ultimate channel capacity is the focus of Section 10.7.

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Section: Fiber Dispersionmentioning

confidence: 88%

Advanced Lightwave Systems

Agrawal¹

2010

Fiber‐Optic Communication Systems

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“…Chromatic dispersion broadens an optical signal and limits the signal transmitted speed and distance [1]. Using a coherent receiver, the optical signal may be equalised using digital signal processing (DSP) techniques.…”

mentioning

confidence: 99%

“…Because the delay-spread caused by chromatic dispersion is proportional to signal bandwidth [1], the signal of each filter bank has far smaller delay-spread than the fullband signal. With smaller bandwidth, the subband signal may be further downsampled.…”

mentioning

confidence: 99%

“…For (2), both H(z) and G(z) can be a square-root raised cosine filter with cutoff frequency of +p=N . The transfer function of fibre chromatic dispersion is FðvÞ ¼ exp (1=2jb 2 Lv 2 ), where L is the total fibre length and b 2 is the group velocity dispersion coefficient [1]. Using the first subband of C 0 (z) as an example but ignoring the delay, C 0 (z) should have a response of exp ( À 1=2jb 2 Lv 2 ).…”

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confidence: 99%

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