Wang Muguang

A Simple Loop for Simultaneous OTDM Demultiplexing and Clock Recovery

A simple and stable loop consisting of a pair of concatenated electroabsorption modulators (EAMs) and 10 GHz clock recovery module is presented and demonstrated experimentally for simultaneous demultiplexing and clock recovery for OTDM networks. The 10Gb/s demultiplexed signal and 10 GHz recovered clock are successfully implemented from 80 Gbit/s and 160 Gbit/s OTDM signals utilizing the loop. The loop based on EAM-PLL can provide excellent tolerance range (> 5 dB) of the OSCR of the source laser, and the recovered clock signal exhibits low rms jitter over a dynamic input optical power range of 15 dB.

A Clock Enhanced Loop for Simultaneous Error-Free Demultiplexing and Clock Recovery of 160 Gb/s OTDM Signal Single-Channel Transmission over 100 km *

A simple clock enhanced loop of cascaded electro-absorption modulators (EAMs) and 10 GHz clock recovery modules is presented. The intensity of harmonic of clock-frequency component is analyzed theoretically and verified experimentally in a 160 Gb/s OTDM 100 km transmission system. The 10 GHz clock component is enhanced obviously before launching into the clock recovery module and the recovered clock signal exhibits low rms jitter of < 400 fs. Moreover, completely error-free (10−12) transmission is observed for more than two hours without using forward error correction technology. The power penalty is about 3.6 dB. The proposed loop has merits of enhancing base clock component, simultaneously de-multiplexing and clock recovery, which make the performance of this loop more stable and high suppression of non-target channels.

Dynamic Polarization-Mode-Dispersion Compensation for 160 Gbit/s OTDM Systems

We report on 160 Gbit/s RZ (return-to-zero) code transmission experiments including a dynamic polarization mode dispersion (PMD) compensation. The 2.5-ps first-order and 15-ps2 second-order PMD are compensated for. The PMD compensation time is within 24 ms. The experimental results show that a significant improvement of system performance can be achieved by auto-correlative curves.

Zero-Chirp Return-to-Zero Pulses Generation with Two Single-Driver z-Cut Mach–Zehnder Modulators

A novel method is proposed to suppress the frequency chirp of single-driver z-cut Mach–Zehnder modulators. Theoretical analysis shows that by multiplying the output pulses of a half clock frequency driving single-driver z-cut modulator with the one delayed odd multiple bit duration, the frequency chirp can be removed entirely, and return-to-zero (RZ) pulses with duty cycles of about 25% and 56% are obtained. An experimental scheme is proposed to validate the proposed method. The experimental results show that perfect 40 GHz zero-chirp RZ pulses can be obtained by using this scheme.

The study of multifunctional intelligent fiber amplifier

In this paper, a kind of multifunctional intelligent fiber amplifier with gain flattening, automatic gain control (AGC), automatic power control (APC), chromatic dispersion compensation, amplified spontaneous emission (ASE) noise filtering is developed by using long-period fiber grating (LFG), uniform Bragg grating, chirp fiber grating and APC circuit. This amplifier have a variety of applications in optical communication system

Dynamic adaptive PMD compensation in a 40Gb/s OTDM system

An experiment of two-stages four degrees high-order polarization mode dispersion (PMD) compensation in 40 Gb/s optical communication system with a large PMD is reported. The former stage adopts polarization controller and fixed time-delayed line of polarization-maintaining fiber (PMF). The second stage consists of a polarization rotator and a tunable differential group delay (DGD) line that is based on magneto optical crystal. The second stage is used to compensate remnant first-order PMD. The PMD monitoring technique adopted degree of polarization (DOP) as error signal. A novel practical adaptive optimization algorithm was introduced in dynamic adaptive PMD compensation. Some experimental results show that large PMD is compensated by this compensator in a 40 Gbits/s non-return-to-zero (NRZ) OTDM transmission systems. A significant improvement of system performance can be achieved in the eye pattern of a received signal. Most first-order compensating ability of the compensator is 35 ps. Second-order compensating ability of the compensator is 200 ps2 . The optimum compensating time is within several milliseconds