GIBON was addressing the demonstration of very high bit rate opto-electronic transceivers suitable for 100G Ethernet applications, with the objective of demonstrating the highest speed components integrating the optoelectronic transducers (light modulator and photodiode) with their driving electronics (driver and preamplifier respectively). New optoelectronics components were developed based on designs experienced at lower bit rates and their characteristics were optimised in order to match specifications derived from systems considerations.
In order to reach the 100 Gbit/s objective, the integration technology for the transceivers was as important as the optoelectronic devices characteristics. Two parallel paths toward integration were followed in this project for the transmitter and receiver: monolithic integration of the laser and modulator for the transmitter, of the photodiode and electronic preamplifier for the receiver. Moreover a multi-chip integration approach was then retained for the close association with the higher-speed electronic circuits, namely the selector driver and demux stage respectively. Guidelines for the design of integrated devices as well as for the components packaging were given by a supporting Electro-Magnetic simulation activity. This project was completed by an assessment of the fabricated components with respect to the projected application.
To demonstrate the feasibility of transmitters and photo-receivers able to support a 100 Gbit/s OOK modulation, 4 main objectives were identified.
- Objective 1: extended bandwidth transmitting and receiving opto-electronic components, compatible with a 100G Ethernet ETDM application.
- Objective 2: compact 100G Ethernet transceiver front-end modules through purposely developed integration / packaging technologies
- Objective 3: electro-magnetic modelling of the integration approach and large signal modelling of HBTs for driver applications
- Objective 4: 100 Gbit/s test bench for transceivers assessment with respect to the 100G Ethernet applications
Significant achievements were reported by GIBON, in the area of packaged opto-electronic components for 100 Gbit/s NRZ transmission.
- High-speed optoelectronic transmitters: beyond the first report by GIBON of an EML operating at 100 Gbit/s at last OFC, a major achievement was the demonstration of a suitable packaging technology. The performance achieved (2dB extinction ratio) was limited by the mismatch between the DC characteristics of EML and driver.
- High-speed optoelectronic receivers: very high-speed packaged photodiodes with suitable bandwidth and responsivity have been developed, as well as photodetectors with internal gain provided by an integrated TWA. Moreover demultiplexing photoreceivers were developed, and error-free operation demonstrated at 107 Gbit/s.
- Associated microelectronics: GIBON achievements in high-voltage driver amplifiers based on the InP HBT are also world-leading results.
These achievements are resulting from the close collaboration of partners within GIBON, and the project was instrumental in reaching such results.
While first standards are expected soon, regarding 100G Ethernet and related technologies, trends are towards using available technologies for client interfaces: 10x10 Gbit/s or more likely 4x25 Gbit/s in a multilane approach, or high spectral efficiency coding (e.g. DP-QPSK) for line transport (OIF recently retained DP-QPSK for long haul DWDM transmission). However, it was shown through the GIBON project, that 100 Gbit/s OOK transmission has a real potential for transmission over spans of several tens of km. The inherent simplicity of the OOK modulation scheme is still a strong and actual reason to further develop this technology for future standardisation and deployment.