Introduction

In late 2023, the French Defence Innovation Agency (AID), through the French Armament Directorate, launched a new satellite named Keraunos with the aid of two novel French Space companies, Cailabs and Unseenlabs (AID, 2O24). The project, along with others like Toutatis and Yoda (Bosquillon, 2024), contribute to the French 2024-2030 Military Programming Law (AID, 2024). The mission is meant to test the potential of space Optical-Laser Infrared (OLI) communications between space and ground segments of communications networks. During the summer of 2024, these three entities performed a successful test (Ruitenberg, 2024). The test was followed by a joint announcement on September 10th, 2024, claiming the world’s first stable OLI high-speed communications “end-to-end” downlink between a low orbit nanosatellite and an optical ground station, which lasted for several minutes (AID, 2024). Despite the possibility of classified initiatives and recent breakthroughs by NASA (Powers, 2024), China (Xinhua, 2024), and others (Depond, 2024), this was the first commercial test of its sort (Bosquillon, 2024), marking a new age for space to ground optical-laser infrared (OLI) communications.

OLI Communications vs Radio Frequency System

To fully comprehend the military pertinence of OLI communication speed, one must first dive into the building blocks that make up Infrared systems and traditional Radio Frequency communications and how they differ. Radio waves and infrared light are components of electromagnetic (EMG) spectrum radiation, although they are located within different ‘bands’ of the spectrum and frequencies, measured in Hertz. The EMG spectrum consists of electromagnetic radiation, but it can also be described as a continuum of photons (light particles) where the only difference is photon energy intensity (Goddard Space Flight Center, 2013). Radio and microwaves (3 KHz – 300 GHz) are composed of the lowest energy photons in the EMG, from Very Low Frequency (VLF) to Extremely High Frequency (EHF). As the photon energy intensity increases, so does the frequency of the waves (Goddard Space Flight Center, 2013). As frequencies increase, so does the bandwidth, which means more volumes of data can be downloaded per transmission, requiring fewer overall transmissions (Manning & Schauer, 2023). Infrared waves (used for Optical-Laser communications) come right after radio and microwaves in the EMG spectrum in terms of photon energy intensity, with slightly smaller wavelengths and consequently higher frequencies (300 GHz – 400 THz) and bandwidths (Goddard Space Flight Center, 2013). The key takeaway here is that although RF and Infrared are made up of the same building blocks, having higher frequencies and bandwidth allows Infrared light to communicate, though not necessarily travel, faster and transmit more information at once.

OLI’s Pertinence to Military Applications, Tactical Advantages & Limitations

The main advantages of OLI communications and their pertinence to military applications can be summarised in four main categories: speed, security (discretion), flexibility and low weight and low costs (Manning & Schauer, 2023). An additional advantage is regulation freedom from the abundant regulation on traditional Radio Frequencies (RF), as there are none yet on OLI communications (AID, 2024). This lack of regulation is particularly an added advantage in the context of hybrid-hyper warfare, which causes progressive information congestion (Lt. Col. Doll & Capt. Schiller, 2019). It is also helpful considering that the EMG spectrum for RF is already saturated from both private and public sector use (European Communications Office, 2023).

In terms of actual speed, all EMG bands travel at light speed. Transmission cycles and data volume capability are the variables accounting for speed. Whereas with traditional RF systems, the average transmission speed is 5Gb/sec, OLI transmission rates can reach around 200Gb/sec or 40x higher (Manning & Schauer, 2023), with the potential for data rates to reach levels of 10 to 100 times higher than traditional RF (Powers, 2024). According to NASA (2023), it would take nine weeks to transmit a full-resolution map of Mars back to Earth using RF, but only around nine days with OLI.

Another advantage of OLI communications is its overall flexibility in logistics, where the lighter and less voluminous nature of OLI components opens the possibility of alternative setups. This means, for example, that optical ground stations can be integrated into existing command and data centers, removing the need for traditional remote antenna locations reducing the overall transmission costs (Manning & Schauer, 2023). Cheaper, faster logistics, and set-up of such infrastructure, are thus an asset for this type of communication system. Additionally, OLI systems have, on average, 25% less power consumption than traditional RF communications (Manning & Schauer, 2023).

Compared to a normal RF transmission, whose beam width is fairly wide (like an outward stretching funnel) and can be received by multiple ground antennas, an OLI beam is extremely narrow (like a cylindrical cable) and precisely targets the receiver, in this case, an optical ground station (NASA, 2023). The “radio footprint” (Ruitenberg, 2024) is thus substantially reduced, which, on the one hand, makes it much harder to perceive, track and jam by adversarial technology, but it also means that any deviation from the transmitter or the receiver will risk loss of transmission (Manning & Schauer, 2023). In this sense, one of the security advantages of OLI systems is also one of its limitations. Additionally, environmental conditions like rain and cloudy weather have been known to disrupt OLI communications, although this was an issue Cailabs’ y(2024b) photonic technology innovation has tackled with adaptive ground receivers and successfully bypassed with Unseenlabs’ Keuranos nanosatellite (Bhardwaj, 2024).

The French AID has already asserted the viable application for military use and its intended implementation of OLI communications systems for next-generation military satellites targeting multi-domain operations, including “mobile, land, naval or air platforms” (AID, 2024). OLI systems present several military tactical advantages when compared to traditional RF, particularly as a backup channel or a classified link, complementing and diversifying current communication channels, thus enhancing overall resilience. The validation of OLI communications by the French Keuranos test, particularly for bypassing atmospheric disturbances, hails a new mark for the operational use of OLI in space-to-ground communications. This could also highly benefit and enhance European land forces’ communication capabilities. Moving forward, the applications and benefits presented by OLI suggest it will progressively become a widely used technology in multiple sectors, even if they don’t completely replace traditional RF infrastructures.

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