Burst-mode Optical Transmitter And Clock Technology Research,

In the OBS (Optical Burst Switching), one of the critical technologies is the transmission of the burst-mode data in the data transmission from the edge node to the core node. In the PON (Passive Optical Networks), the data transmission from ONU (optical network unit) to OLT (optical line termination) in the up-stream direction employing the style of TDMA (Time-Division Mutiple Access), is the burst-mode transmission also. So, the design of the burst-mode transmitter is substantially necessary. The difference of the optical signal of the burst-mode and conventional communication system mainly lies in: the deviation of the amplitude; the deviation of the phase; long continual "0"and "1". ATM-PON system is a system of the CWDM (crude wavelength division multiplex), in the design of the burst-mode optical transmitter, extinction ratio and light-off optical power is considered the main factor to design, and the chirp of the frequency is not the main factor of the confine. We use the style of directly modulation of the optical source. Aiming at the 155Mb/s up-stream velocity of ATM-PON system, we design the circuit of the burst-mode optical transmitter. We make the frequency synthesis of the PLL (Phase-Locked Loop) get 155Mb/s clock source. By drivering the optical transmitting modules NTR-2632, we get the optical signal. Lastly test the output parameter of the burst-mode transmitter: extinction ration is 10dB, average optical power -10.5dBm. Based on the burst –mode transmitter, we employ the building system of the burst-mode signal. And get the burst-mode signal of different amplitude; the discrepancy of signal amplitude is 5dB. Aiming at the OBS networks mainly based on the DWDM (Dense Wavelength Division Multiplex) system, the chirp of the frequency is the main factor of the confine to the system. When the velocity is 1.25Gb/s and above, because of the disadvantage of severe frequency chirp, more transmission delay, and weak control of optical peak-power in the direct modulation, so external modulation is the best-optimum choice to high-speed and burst-mode transmission, especially to the DWDM system. In the paper, aiming at MQW-EAM (multiple-quantum well-electroabsorption modulation), we research and compute the extinction and frequency chirp in detail, and describe the impedance match, and construct the simulation model of MQW-EAM, in the end we perform the simulation to the driver circuit and whole circuit. The result of the simulation shows: the 5Gb/s velocity can achieve a good result. In the end, we analyses simply the main parameter of the performance describing the clock-source system, and the factor influencing the performance of clock.