Nonlinear Distortion Analysis of Directly Modulated ... - 연세대학교

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Normalized Main Mode Power (dB)0-10-20-30-40-50(a) -2 dBm58GHz(b) 2dBm-601549.8 1550.0 1550.2 1550.4 1550.6 1550.8ML Wavelength (nm)(c) 6dBmFigure 4.2 Normalized main-mode power according to the ML injection wavelength. (a) MLpower is –2 dBm (b) ML power is 2 dBm. (c) ML power is 6 dBm.48
B. Nonlinear Distortion Suppression by Sidemode Optical InjectionLockingNext, the nonlinear distortion characteristics of directly modulated lasersare investigated in case of sidemode optical injection locking. For generatingsubcarriers, the SL is directly modulated by two RF signals (f 1 = 2.8 GHz andf 2 = 2.9 GHz). In this experiment, we measure the power of the secondharmonic distortion (SHD), second order intermodulation distortion (IMD2),and third order intermodulation distortion (IMD3). The SHD is defined as theratio of power at frequency 2f 2 to the power at fundamental frequency. TheIMD2 and IMD3 are defined as the ratio of power at frequency f 1 +f 2 and atfrequency 2f 2 -f 1 , respectively, to the power at fundamental frequency. For thesidemode optical injection experiment, the injection light power is 6 dBm andthe wavelength is set at 1550.434 nm. Under these conditions, the laser mainmodeis suppressed about 50 dB. Fig. 4-3 shows the detected RF power of thesecond harmonic and the second order intermodulation product. The input RFpower is measured at the RF signal generator output. The linearly fitted linesshow the slope of fundamental frequency power is one and those of the secondharmonic power and IMP2 are two. These are the usual characteristics ofmodulation frequency power, second harmonic power and IMP2. As can beseen in the figure, the SHD and IMD2 are suppressed by more than 10 dB bymeans of sidemode optical injection locking. Like main-mode injectionlocking, these are the result of a resonance frequency shift toward higherfrequency. In this figure, the fundamental frequency power is slightlydecreased after light injection. This is also due to a shift of resonance49
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Nonlinear Distortion Analysis of Di
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IndexFigure Index ⋅⋅⋅⋅⋅
Page 7 and 8: Figure 3.11 Simulation results of I
Page 9 and 10: AbstractNonlinear Distortion Analys
Page 11 and 12: I. IntroductionIn the past, telecom
Page 13 and 14: solution for increasing the detunin
Page 15 and 16: [8, 9, 10]. This phenomenon occurs
Page 17 and 18: 0Optical Power (dBm)-10-20-30-40-50
Page 19 and 20: is the laser nonlinear transfer fun
Page 21 and 22: (3) Laser nonlinear transfer functi
Page 23: D11= τng2− 2( N00[(1 − 2εP)(
Page 26 and 27: f kn . The order of the IMP corresp
Page 28 and 29: 100-10Amplitude (dB)-20-30-40-50-60
Page 30 and 31: -20Amplitude (dB)-30-40-50-60-70thr
Page 32 and 33: locking to suppress nonlinear disto
Page 34 and 35: By using this system matrix, the sy
Page 36 and 37: Harmonic Power (dBm)0-10-20-7 dBc2
Page 38 and 39: these suppression values are depend
Page 40 and 41: oscillation [21]. This will result
Page 42 and 43: 20Detuning Frequency (GHz)0-20-40-6
Page 44 and 45: nonlinear phenomena simulation shou
Page 46 and 47: Normalize Frequency Response (dB)10
Page 48 and 49: effects.Finally, for verifying the
Page 50 and 51: IMD2 Suppression (dB)15141312111098
Page 52 and 53: -20-30-40-0-60-70-802.70 2.75 .80 2
Page 54 and 55: IV. Nonlinear Distortion Suppressio
Page 56 and 57: -10Optical Power (dBm)-20-30-40-50-
Page 60 and 61: frequency.Then, reduction of IMD3 i
Page 62 and 63: -10-20Detected RF power (dBm)-30-40
Page 64 and 65: -20RF Power (dBm)-30-40-50-60-70-80
Page 66 and 67: V. SummaryIn analog fiber-optic lin
Page 68 and 69: VI. References[1] W, I, Way, “Bro
Page 70 and 71: quantum-well lasers,” J. Quantum
Page 72: .__________________________________
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Nonlinear Distortion Analysis of Directly Modulated ... - 연세대학교

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