• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.4
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• pp.331-341
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• 2002

It is expected that the SCM (Subcarrier Multiplexing) optical link system, in which a number of small scale base stations with only antenna and RF transceiver are connected to central station through optical fiber, is in demand. In order to analyze the performance of SCM optical link system fur RF signal transmission, MZ(Mach-Zehnder) modulator's transfer function is modelled as nonlinear form with the cube of input signal. And considering the multiple access interferences occurred In the demodulation of other users'CDMA signals with multipath components after passing through MZ modulator, the BER performance is analyzed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.11
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• pp.1113-1120
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• 2003

It is expected in the future that the demand of optical subcarrier multiplexing system, in which a number of small size base stations with only antenna and RF transmission are connected to central station using optical fiber, will be increased in the CDMA digital cellular mobile communication network. In this paper, in order to analysis the performance of optical SCM system fur CDMA RF signal transmission, MZ modulator is modelled as a non-linear transfer function with cubic operation. The performance degradation due to multipath signals and other user signals through MB modulator is analyzed and the performance is improved using the Rake receiver.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.77-80
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• 2001

In this paper, it is analyzed the statistical characteristics on the transmission performance of the optical SCM transmission in the CDMA RF signal relay system. Using Mach-Zehnder modulator, optical signal is regenerated into CDMA RF signal. Transfer function model of mach-Zehnder modulator is approximated to the third power of the input signal using Taylor series. BER results are analyzed under the multiple access interference and multi-path fading environment.

• Proceedings of the Optical Society of Korea Conference
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• 2002.11a
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• pp.176-177
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• 2002

• Proceedings of the Optical Society of Korea Conference
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• 2002.11a
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• pp.178-179
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• 2002

We generate optical millimeter-waves by double-sideband suppressed carrier (DSB-SC) modulation using a Mach-Zehnder (MZ) modulator biased at the minimum power. The DSB-SC modulation allows the high-frequency intensity modulation for millimeter-wave generation at the twice of the MZ modulator driving frequency.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.7
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• pp.17-22
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• 2010

We have proposed and experimentally demonstrated a novel fiber Bragg grating (FBG) sensing interrogation method using bidirectional modulation of a Mach-Zehnder electro-optical modulator (MZ-EOM). The proposed structure consists mainly of a broadband light source (BBS), FBG, MZ-EOM, chirped fiber Bragg grating (CFBG), and photodetector (PD). We have obtained the transfer functions of the proposed structure and calculated the time delay from the change in the free spectral range (FSR) for ten wavelengths over the frequency range of 505 MHz to 525 MHz. The results show that the time delay and the wavelength variation have a good linear relationship with a gradient of 12.9 ps/0.2 nm, which can be usefully applied to FBG strain or temperature sensors and other multiplexed sensor applications.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.7A
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• pp.672-677
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• 2007

A novel method for stabilizing the bias of an Electro-Optic Mach-Zehnder modulator has been proposed and demonstrated to maximize the switching extinction ratio in burst mode packet traffic. By sampling and minimizing the off-level output power of the modulator, a high extinction optical gate switch in obtain regardless of the variation of the packet traffic density.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10A
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• pp.935-942
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• 2006

The performance of ROF systems can be severely degraded due to nonlinear effects in the channel. Also, Orthogonal Frequency Division Multiplex(OFDM), as a standard for broadband wireless and mobile internet networks, is being proposed for deployment with ROF systems to facilitate the total performance of a system. In this paper, at first, the performance of the OFDM-based RoF system with a Mach-Zehnder(MZ) modulator distortion effects has been analyzed at 5.8GHz. Evaluation of mean-squared error of the proposed OFDM-RoF system was carried out to compare with the conventional single carrier system based RoF link after the modulator distortion case and also for fixed signal to noise ratio(SNR) of 20dB using undistorted OFDM signal. Nominal and offset baising pre-distortion techniques are applied in proposed system to linearize the OFDM-RoF link. Finally, a comparison between the aforementioned pre-distortion techniques applied showed important observation in terms of distortion-free dynamic range and SNR to choose offset pre-distortion technique for our proposed system.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.6
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• pp.119-123
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• 2010

The transmission performance of 10Gb/s optical duobinary transmitters implemented by using a Mach-Zehnder(MZ) modulator and an optical delay interferometer is presented. We investigated the theoretical impact of transmission systems by the modulator driving voltage ratio(=driving voltage/switching voltage) and the optical interferometer time delay to improve transmission distance using computer simulation. By reducing the driving voltage ratio and optimizing the partial bit time delay, the transmission performance has been improved greatly.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.203-204
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• 2006

We present and demonstrate a novel method of alternate-phase return-to-zero (RZ) signal generation and pulse-amplitude equalization simultaneously in a rational harmonic mode-locked fiber ring laser, using a dual-drive Mach-Zehnder (MZ) modulator. By adjusting the voltages applied to both arms of the modulator, the rational harmonic mode-locked pulse trains are equalized in their amplitudes. In addition to that, the amplitude-equalized pulse trains multiplying the repetition rate at ${\sim}10\;GHz$ have alternate $\pi$ phase difference between adjacent pulses. The alternate-phase RZ signal generated by the proposed method enhances transmission performance through the single-mode fiber (SMF) links without dispersion compensation.