A new research project aims to develop space photonics hardware that enables terabit optical connectivity for next-generation, high-capacity telecommunication satellites. The Multi-gigabit, Energy-efficient, Ruggedized LIghtwave eNgines (MERLIN) for advanced on-board digital processors project is a collaborative mission set to run from November 2013 to October 2016. It is funded by the European Union’s (EU) 7th Framework Program.
The latest terabit-capacity satellites will require a new approach to address digital on-board processors that rely on electronic technologies to combine scalability, technical feasibility, power-efficiency, and cost-effectiveness. The MERLIN project outlines its plan through four main development objectives. The technologies will be integrated on a space-grade photonics platform to provide ruggedized transceiver modules with 150 Gb/s throughput and <10 mW/Gb/s energy consumption.
The first is an advanced electro/photonic vertical platform for harsh-environment embedded opto-electronic engines. The platform will be based on low-temperature-co-fired-ceramics (LTCC) circuit substrates. The novel LTCC structures, in combination with high-precision bonding and assembly, will be used to achieve the necessary micron-scale optical alignment for multi-core optical fibers. The platform will be suitable for both stand-alone multi-channel optical transceivers and for application-specific-integrated-circuit/field-programmable-gate-array (ASIC/FPGA) packaging with embedded optical interconnects.
Next is the development of multi-core compatible and energy-efficient harsh-environment vertical photonics. This involves the fabrication of energy-efficient, extended-temperature gallium-arsenide (GaAs) 850-nm vertical-cavity surface-emitting laser (VCSEL) and photodiode arrays. GaAs and the ULM manufacturing process were chosen due to their proven radiation-hard performance, maturity, and readiness for foundry-based industrial mass fabrication.
The following objective is for the development of low-power multi-channel VCSEL drivers and transimpedance amplifier (TIA) integrated circuits (ICs). The multi-channel driver ASICs will be adapted for co-integration and RF interconnection with the active photonics on the LTCC platform. The ICs will be developed for operation as high as 25 Gb/s. A total chip throughput of 150 Gb/s will be reached through the integration of multi-channel ICs. They will be fabricated using an IHP Microelectronics silicon-germanium (SiGe) bipolar-complementary-metal-oxide-semiconductor (BiCMOS) process suitable for the production of electronics for aerospace applications. According to MERLIN, the ICs will purportedly be the first radiation-hardened multi-channel drivers operating to 25 Gb/s and with a five-fold reduction in energy consumption against current 10 Gb/s radiation-hardened ICs.
The last objective is the development of radiation-hardened multicore, multimode fibers to be coupled with the opto-electronic chips. MERLIN will employ advanced-modified-chemical-vapor-deposition (MCVD) technology to accurately control the index of refraction of each fiber. This will help to enable 25-Gb/s multimode transmissions. OFS recently signed on to the project to help in the fabrication of the fibers.