Jiannan Zhu

First demonstration of a full C-Band tunable WDM-PON system with novel high-temperature DS-DBR lasers

We demonstrate automatic operation of a cooler-less tunable-laser based WDM-PON system. Using a pilot-tone based overhead channel and centralized wavelength locking scheme, 1 Gb/s and 10 Gb/s data transmission is demonstrated in a multi-user set-up.

First demonstration of a WDM-PON system using full C-band tunable SFP+ transceiver modules [invited]

In this paper, a wavelength-division-multiplexing passive optical network (WDM-PON) system using small form-factor pluggable plus (SFP+) packaged full C-band tunable transceivers is demonstrated for the first time to our knowledge. Within the transceivers, a novel digital-supermode distributed Bragg reflector (DS-DBR) laser with a monolithically integrated Mach-Zehnder modulator is employed as the transmitter. A generic current control algorithm is used to drive the DS-DBR laser, which employs a laser current training sequence ensuring successful operation without the need for individual laser characterization. A pilot-tone-based feedback control loop is implemented using embedded hardware, which is able to lock the output wavelengths from three identical optical network units with less than ±3 GHz deviation from their assigned channels. Error-free transmission is achieved at a 10 GbE data rate. With the feedback control loop running continuously, the system shows a sensitivity of -23 dBm for a bit error rate of 10-12.

100 Gb/s Uncooled DWDM using Orthogonal Coding for Low-cost Datacommunication Links

We demonstrate a 10 × 10 Gb/s uncooled DWDM system using orthogonal coding on adjacent carriers, assuming the use of a monolithically integrated sources. A power saving of 72% is expected over traditional WDM.

Tunable WDM-PON System with Centralized Wavelength Control

We report on the state of the art and future prospects and challenges of optical access networks. Details on a recent field demonstration of a novel tunable WDM-PON system with novel T-SFP+ modules will be presented. Furthermore, the concept of centralized wavelength control of the optical network unit wavelengths will be explained as well as different realization options of pilot-tone based communication channels. Finally, a control concept for tuning the DS-DBR laser will be shown.

Field demonstration of a tunable WDM-PON system with novel SFP+ modules and centralized wavelength control

We report on a demonstration of a novel tunable WDM-PON system over 25km of field deployed fiber. We show error-free operation at 1GbE with sensitivity better than -30dBm and centralized control of the ONU wavelengths.

Athermal Colorless C-Band Optical Transmitter System for Passive Optical Networks

This paper reports an uncooled transmitter system using a digital super-mode (DS) distributed Bragg reflector (DBR) tunable laser, which is able to act as an athermal, wavelength agnostic transmitter suitable for wavelength division multiplexed (WDM) passive optical network (PON) applications. An open-loop laser current control algorithm is designed to compensate autonomously for wavelength drift, thus allowing constant operating wavelength to be achieved regardless of ambient temperature. An improved wavelength accuracy of ±3 GHz is achieved when using low bandwidth feedback from the central office using information from a centralized shared wavelength locker. The entire laser start-up, channel selection and subsequent wavelength control is autonomous and has been implemented on micro-controllers and field programmable gate arrays. We demonstrate a three channel WDM-PON system comprising an uncooled packaged DS-DBR laser in the presence of two neighboring interfering channels. Error free transmission over 40 km single mode fiber of 10 Gb/s externally modulated NRZ data, is achieved for each of 48 C-band channels on the 100 GHz ITU grid. Successful athermal operation is demonstrated by sweeping the ambient temperature of the laser from 15 to 70 °C with a maximum wavelength deviation for any channel of no more than 0.1 nm.

MIMO DWDM System Using Uncooled DFB Lasers With Adaptive Laser Bias Control and Postphotodetection Crosstalk Cancellation

A proof-of-principle demonstration of a multiple input-multiple output (MIMO) dense wavelength division multiplexing (DWDM) system is reported. It uses standard uncooled distributed feedback lasers with intensity modulation-direction detection (IM-DD), in which the temperature of each laser is allowed to drift independently within a 50 °C temperature range. A feedback-based laser bias control algorithm is introduced to guarantee acceptable wavelength spacing and a postphotodetection minimum mean square error decoder is applied to cancel the interchannel crosstalk. The relative sensitivity of the MIMO receiver in both a random laser temperature drift scenario and a worst-case scenario are investigated by simulations in MATLAB. Experimental results for a 40-channel × 12.5 Gb/s DWDM system transmitting over 28 km of single-mode fiber with worst possible wavelength distribution prove the feasibility of the technique.

Uncooled DWDM Using Orthogonal Coding for Low-Cost Datacommunication Applications

We describe a novel dense wavelength-division multiplexed systems (DWDM) system where by introducing orthogonality between adjacent channels and by using overlapping arrayed waveguide grating filter profiles, laser transmitters may operate without the need for thermoelecric cooling. Compared with a traditional DWDM system, a power consumption saving of up to 68% may be realized using this scheme. Results of a proof-of-principle 100 Gb/s (10 × 10 Gb/s) experiments that use alternating NRZ and Manchester (CAP-2Q) modulation is reported.