Conceptual illustration for Space-BACN. [Image: DARPA]
Coherent Corp., a newly rebranded global supplier of lasers and photonics technology, announced on 13 September that it had won a US Defense Advanced Research Projects Agency (DARPA) contract for the agency’s Space-Based Adaptive Communications Node (Space-BACN) program. Under the agreement, the company—formed after II–VI Inc. acquired Coherent in July—will develop coherent optical transceiver technology that will improve communications between low-Earth orbit satellite constellations.
"Space bacon"
Both governments and companies like SpaceX have been launching low-Earth orbit satellites at an unprecedented rate for the last few years. However, satellite constellations manufactured by different entities have numerous incompatible and often proprietary optical intersatellite links that block them from communicating with each other.
To combat this issue, DARPA, which falls under the US Department of Defense, unveiled Space-BACN—pronounced “space bacon”—last September. The program’s goal is to connect various low-Earth orbit satellite constellations by creating low-cost, reconfigurable laser communications terminals.
DARPA wants the terminals to be low cost and easy to use and integrate, and the agency set objectives to ensure they meet those criteria: a speed of 100 Gbps to match most optical standards, a limit of 100 W to curtail power consumption and a maximum price tag of US$100,000 per terminal to make them affordable.
Reconfigurable modem
Coherent is tasked with creating coherent optical transceivers for a reconfigurable low-power modem, one of the three technical areas required by the program. The company is aiming for the modems to be compatible with most existing single-wavelength communications protocols and able to readily adapt to work with new waveforms as they are introduced. In addition, the modems will be made to support multiple optical waveforms at the maximum total data rates of 100 Gbps on a single wavelength while meeting size, weight, power and cost constraints.
Two other required pieces of technology that DARPA assigned other companies to develop are a low-cost optical aperture capable of coupling with single-mode fibers and a cross-constellation command-and-control method that can automate interactions between government and commercial satellites.
“Advances in digital technology, together with falling launch costs, have made it possible for many groups to launch constellations of compact satellites possessing a multitude of capabilities, enabled by high-speed laser communications,” said Chris Koeppen, Coherent’s chief technology officer, in a press release. “Beyond just defense applications, these satellite arrays offer tremendous potential for low-cost global communications, sensing, imaging, space exploration and more.”