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Lasercom-on-chip for next generation, high-speed satellite constelation interconnectivity

Periodic Reporting for period 2 - ORIONAS (Lasercom-on-chip for next generation, high-speed satellite constelation interconnectivity)

Reporting period: 2019-11-01 to 2021-04-30

Photonics have revolutionized the world of telecommunications. During the past decades fiber optic connections have infiltrated every part of the network; from short, few-meter connections within datacenters up to multi-km long-haul links. On a global scale, our continents are linked through fiber optic cables that are laid out on the bottom of the oceans; ~750.000 km of fiber optic cable is installed today to form the sub-marine networks – this is ~3 times the distance between the Earth and the Moon. Now photonic technology is ready to revolutionize again the telecoms world; this time it’s not through the land or the ocean but through a new communication network that will be installed in space.
The vision is to set-up a mega constellation network of satellites which will communicate through laser beams – just as fiber optic cables are doing in terrestrial networks - with the extra benefit of lower latency simply because light travels much faster in vacuum than in glass. Such network is expected to have a drastic impact on the provision of high-quality broadband internet in the coming future. Being a satellite network means that it should be accessible to the most isolated parts of the planet– typically known as Other 3 billion – and being ultra-fast means that it can provide low latency connectivity to already connected parts where “network response” is of prime concern – such as enterprise commercial networks. However, such a network will have an equally drastic impact on the number of satellites orbiting the Earth. The high volume of satellites required to provide a global coverage and at the same time the small physical size of each satellite impose stringent requirements on the cost, size, weight and power consumption (C-SWAP) of the “laser modems”; the systems that deliver the transmission and reception of the laser communication beams within the satellite optical network. However, the current laser-com terminals are built with discrete transceiver and amplifier components and as such systems are bulk, complex and expensive. For a viable business plan, end-users are ready to embrace a technology switch that will hit the right C-SWAP targets; such technology should leverage the great strength of photonic integration. This is the merge of elements and functionalities on chip-scale circuits that can be fabricated within semiconductor foundries just as electronic circuits are fabricated today for any high-volume consumer-based application.
ORIONAS is a H2020-SPACE research project that aims to provide a photonic technology platform that will disrupt both the shape of laser-com modems as well as the way they are built and tested making a drastic impact on the system C-SWAP. ORIONAS invests in monolithic integration within European BiCMOS and InP foundries to squeeze transceiver and amplifier elements into integrated circuit areas of a few mm2. Leveraging electronic-photonic integration and using hi-rel small form factor fiber (SFF) optics the project intends to demonstrate a cost-effective solution for compact laser terminals that deliver 25 Gb/s to 50 Gb/s data rates through both direct and coherent detection methods.
During its second period, ORIONAS has progressed to manufacturing, assembly, integration and testing activities achieving the following:
o Fabrication of edge coupled Mach-Zehnder Modulator (MZM) electronic-photonic integrated circuit (EPIC) in IHP “photonic-BiCMOS” process. The MZM-EPIC demonstrates monolithic integration of carrier depletion type SiPh MZM and segmented driver in 0.25 um SiGe BiCMOS technology.
o The MZM-EPIC hosts >20 photonic elements plus the BiCMOS MZM driver circuit in a chip area ~15 mm2, including spot-size converters, MMI couplers, multi-segment phase shifters and thermal tuning heaters.
o Fabrication of edge coupled DPSK receiver EPIC. The DPSK-Rx EPIC demonstrates monolithic integration of optical demodulation, balanced photodetection and transimpedance amplification functions.
o The DPSK-Rx EPIC hosts >20 photonic elements plus the BiCMOS transimpedance circuit in a chip area ~5 mm2, including spot-size converters, MMI couplers, waveguide coils, Ge diodes and thermal tuning heaters.
o Fabrication of a DPSK optical transmitter sub-assembly through the assembly of the MZM-EPIC with a narrow linewidth DFB laser diode and a fiber array through the use of micro-optics and a glass interposer.
o Tape-out of edge-coupled IQ-MZM EPIC in IHP “photonic-BiCMOS” process. The IQ-MZM-EPIC demonstrates monolithic integration of nested SiPh MZMs and segmented drivers in 0.25 um SiGe BiCMOS technology.
o The IQ-MZM EPIC hosts >40 photonic elements plus the BiCMOS driver circuit in a chip area ~12.65 mm2, including spot-size converters, variable optical attenuators, MMI couplers, multi-segment phase shifters and thermal tuning heaters.
o Tape-out of edge-coupled coherent receiver EPIC in IHP “photonic-BiCMOS” process. The Coh-Rx EPIC demonstrates monolithic integration of optical hybrid (OH), balanced photodetection and transimpedance amplification functions.
o The Coh-Rx EPIC hosts >45 photonic elements plus the BiCMOS transimpedance circuit in a chip area ~6 mm2 including spot-size converters, MMI coupler 90-degree OH, Ge diodes and waveguide bends.
o Fabrication of booster (>20 dBm) Semiconductor Optical Amplifier (SOA) chips using the Semi Insulating Buried Heterostructure (SiBH) process and assembly of the SOAs into compact butterfly packages.
o Fabrication of a radiation resistant high gain (>50 dB) optical fiber pre-amplifier built with small form factor optics and featuring a credit card size footprint and mass as low as 100 grams.
o Fabrication of EGSE implementing control and monitoring of the transceiver and amplifier modules to assist system integration activities.
o Transmission test-bed assembly and preliminary system-level evaluation testing with high-speed OOK and DPSK modulation formats.
ORIONAS has completed the second period of its lifetime which was dedicated to integrated circuit manufacturing, module assembly / packaging and system integration. The next period will complete module development and will perform device-level and system-level evaluation testing which will facilitate the benchmark against the state-of-the-art. The progress made so far in the area of transceivers and optical amplifiers, already suggests that ORIONAS is advancing the state-of-the-art in the following aspects:
a) development of the first edge-coupled optical transceiver integrated circuits that feature full flesh monolithic integration of silicon photonic and BiCMOS electronic integrated circuits. Such approach can facilitate integrated optical devices for high-bandwidth applications that require a higher degree of miniaturization.
b) development of module assembly method for co-packaging of modulator PICs with laser diodes toward integrated PIC-based transceiver modules
c) development of semiconductor booster amplifiers that reduce drastically the amount of components to be qualified and assembled compared to conventional booster fiber amplifier technology.
d) development of the first radiation resistant miniaturized optical pre-amplifier that demonstrates >80% savings in mass and unit area.
RP2 highlights; Transmitter sub-assembly, compact pre-amplifier, SOA module and DPSK receiver EPIC