Cechan Tian

Analysis and control of transient dynamics of EDFA pumped by 1480- and 980-nm lasers

The transient responses of Er-doped fiber amplifier (EDFA) to fast channel adding/dropping processes have been studied and analyzed. The result shows that the speed in which we can control EDFA with a feedback circuit is limited by the physical processes involved in the amplification. We demonstrated that with the combination of electrical feedforward and feedback, the power excursion caused by fast channel adding/dropping processes can be minimized.

Transmission and interactions of WDM burst signals in cascaded EDFAs

By use of AGC technology based on electrical feedforward and feedback, gain excursions of optical burst amplification in six cascaded EDFAs, with or without interaction of another burst, is suppressed to 1 dB or less

Cost-Effective Optical Access Upgrades using Wavelength Shared Hybrid Passive Optical Network Architecture

We propose and demonstrate a novel wavelength shared hybrid passive optical network (WS-HPON) architecture for symmetric gigabit PON capacity upgrades with installed equipment re-use, to bridge the technology gap between gigabit- and WDM-PON systems cost- effectively.

Novel solution for transient control of WDM amplifiers using the combination of electrical feedforward and feedback

Summary form only given. We present a practical and low cost EDFA control solution in which both electrical feedforward and feedback are employed. We have demonstrated that with this automatic gain control technology the gain excursion happening in WDM systems can be drastically reduced.

Optical modulator bias monitoring with two-photon-absorption in Si-APD in advanced modulation formats optical transmitters

We have demonstrated more sensitive monitoring of modulator bias point with two-photon-absorption in Si-APD. For NRZ, RZ and CS-RZ signals, the sensitivity with TPA monitoring is at least double of that with power monitoring.

Data and pulse-carver alignment in high-speed optical transmitters monitored with two-photon-absorption in Si-APD

The timing alignment between the pulse carver and data modulation signals in advanced modulation formats is monitored with two-photon-absorption processes in Si-APD. For 20 Gb/s signals, the monitor is sensitive to within ± 10 ps.