space Archives - EFFECT Photonics

Insights

November 9, 2023

What DSPs Do Optics in Space Need?

The space sector is experiencing rapid growth, driven by numerous privately-owned initiatives aiming to reduce…

The space sector is experiencing rapid growth, driven by numerous privately-owned initiatives aiming to reduce the cost of space flight. As this sector expands, it presents new opportunities for developing optical components in space and satellite communications.

Graph-cost-space-flight — *Figure 1: The cost of a kilogram of payload into space since 2000. Source: Visual Capitalist (data from the Center for Strategic and International Studies)*

However, the challenges associated with the space environment required digital signal processors (DSPs) optimized for optical communications in space. Unlike traditional fiber transmission systems, DSPs for space need to be optimized for receiver sensitivity and signal-to-noise ratio, adapt to signal recovery in the presence of frequent signal losses, and comply with stringent space certification standards.

Signal to Noise Ratio Over Dispersion

In traditional optical fiber communications, the presence of dispersion often leads to signal distortions that require extensive dispersion compensation techniques. However, space is a vacuum medium devoid of most dispersion-related challenges. Consequently, DSPs developed for space-based optical communications do not require the same level of dispersion compensation as their fiber counterparts. Instead, the primary focus shifts toward optimizing receiver sensitivity and improving the signal-to-noise ratio (SNR) to ensure reliable data transmission in space.

Optical signals travel enormous distances in space and will be extremely weak when they reach a receiver. Focusing DSP performance on enhancing the receiver’s sensitivity enables more accurate detection of these weak optical signals.

To achieve this goal, DSPs for space-based optical communications need forward error correction (FEC) methods that are even more robust than FEC used for ground links. These methods employ sophisticated coding techniques that introduce redundancy in the transmitted data, allowing for efficient error detection and correction.

network link with FEC — Figure 2: Simplified diagram of a network link with forward error correction (FEC). The FEC encoder adds a series of redundant bits (called overhead) to the transmitted data stream. The receiver can use this overhead to check for errors without asking the transmitter to resend the data.

Handling Signal Losses in Space

In contrast to optical fiber communications, where signal losses are typically infrequent but often fatal, space-based optical communications experience more frequent but non-fatal signal losses. Therefore, DSPs designed for space must be optimized to handle these intermittent signal losses and ensure efficient signal recovery.

While DSPs for fiber optical links on the ground often rely solely on their error correction methods, DSPs for space-based optical communications might ask more frequently for the signal to be retransmitted. This retransmission can increase the link latency significantly, which can be compensated in part by using satellite networks to provide more redundancy. You can read more about these satellite networks in one of our previous articles.

Space Certification and Standards

While industrial or commercial temperature certifications are typically sufficient for optical fiber transceivers and their components, DSPs designed for space-based optical communications must adhere to more stringent space certification standards. Space certification ensures that DSPs can withstand the extreme temperatures, vacuum conditions, and radiation exposure prevalent in space environments.

*Figure 3: The James Webb Telescope. Space Observatory for the Study of the Universe and exploration of deep space*

Our testing facilities and partners include capabilities for the temperature cycling and reliability testing needed to match Telcordia standards, such as temperature cycling ovens and chambers with humidity control.

Takeaways

The testing process for photonic integrated circuits ensures their reliability and performance. Device-level testing focuses on individual components, allowing for precise characterization and identification of faulty elements. Functional testing evaluates the overall performance of the PIC, ensuring adherence to design specifications. Reliability testing assesses the robustness and lifespan of the PIC under various operating conditions.

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Tags: 5G, certification, Coherent Optical Systems, Data center architecture, dispersion, DSP, DSPs, DVT, Electrical Power, free space optics, Networks, noise ratio, noise ratiom, Optical System-On-Chip (SoC), optics in space, Photonic Integrated Circuit, Photonics, PICs, Pluggable Transceivers, signal, signal loss, space, standard

Insights

June 21, 2023

Coherent Satellite Networks

The current state of the space industry is characterized by rapid growth, technological advancements, and…

The current state of the space industry is characterized by rapid growth, technological advancements, and increasing commercialization. Over the past decade, the space industry has undergone a significant transformation driven by both government and private sector initiatives.

One notable trend is the rise of commercial space companies. Companies like SpaceX, Blue Origin, and Virgin Galactic have made major strides in developing reusable rocket technology, drastically reducing the cost of accessing space. The miniaturization of satellites has also led to an increase in the number of satellites launched. This progress has boosted space applications such as Earth observation, global internet connectivity, and remote sensing.

Cost-space-flight — Figure 1: The cost of a kilogram of payload into space since 2000. Source: Visual Capitalist (data from the Center for Strategic and International Studies)

On the technical side, the main issues in satellite communications include signal latency, limited bandwidth, and vulnerability to weather conditions. Signal latency refers to the delay in transmitting signals over long distances, which can impact real-time applications. Limited bandwidth can result in slower data transfer rates and congestion. Weather conditions like heavy rainfall or storms can cause signal degradation or interruptions.

This article will discuss how satellite networks and coherent optical communications can help address some of these issues.

A New Age of LEO Satellite Constellations

The most important distinction between each satellite type is its orbital altitude or distance from Earth’s surface as it rotates the planet. There are three main categories:

Low Earth Orbit (LEO). Altitude 500 to 1,200km. LEO is densely populated with thousands of satellites in operation today, primarily addressing science, imaging, and low-bandwidth telecommunications needs.
Medium Earth Orbit (MEO). Altitude 5,000 to 20,000km. MEO has historically been used for GPS and other navigation applications.
Geostationary Earth Orbit (GEO). Altitude > 36,000 km. GEO satellites match the rotation of the Earth as they travel, and so remain above the same point on the ground. Hundreds of GEO satellites are in orbit today, traditionally delivering services such as weather data, broadcast TV, and some low-speed data communication.

Asset 6 GEO MEO LEO — Figure 2: Schematic of orbital altitudes and coverage areas

The telecom industry is particularly interested in using LEO satellites to provide enhanced connectivity. Compared to GEO satellites, they can provide higher speeds and significantly lower latencies. As the cost of launching LEO satellites has decreased, more can be launched to provide redundancy in case of satellite failures or outages. If a single satellite experiences a problem, such as a malfunctioning component or damage from space debris, it can be taken offline and replaced without interrupting the network’s overall operation.

Asset 8 Satilite-speed-latency-coverage — Figure 3: Comparison between LEO and GEO satellites for connectivity. Source: BCG Analysis

Many companies are developing massive LEO constellations with hundreds or thousands of satellites to provide low latency and global coverage: SpaceX´s Starlink, Telesat’s Lightspeed, Amazon’s Kuiper, or OneWeb. These LEO satellite constellations can provide true universal coverage compared to terrestrial methods of communication. LEO satellites can connect people to high-speed internet where traditional ground infrastructure is hard to reach, making them an attractive solution to close the connectivity gaps across the world.

Coherent Technology is Vital for Future Satellite Links

Currently, most space missions use radio frequency communications to send data to and from spacecraft. While radio waves have a proven track record of success in space missions, generating and collecting more mission data requires enhanced communications capabilities.

Coherent optical communications can increase link capacities to spacecraft and satellites by 10 to 100 times that of radio frequency systems. Additionally, optical transceivers can lower the size, weight, and power (SWAP) specifications of satellite communication systems. Less weight and size means a less expensive launch or perhaps room for more scientific instruments. Less power consumption means less drain on the spacecraft’s energy sources.

Compared to traditional optical technology, coherent optical technology offers improved sensitivity and signal to noise ratios. This reduces error rates and the need for retransmission, which would significantly increase latency.

Leveraging Electronics Ecosystems for Space Certification and Standardization

While integrated photonics can boost space communications by lowering the payload, it must overcome the obstacles of a harsh space environment, which include radiation hardness, an extreme operational temperature range, and vacuum conditions. The values in Table 1 show the unmanaged environmental temperatures in different space environments.

*Mission Type*	*Temperature Range*
Pressurized Module	+18.3 ºC to 26.7 °C
Low-Earth Orbit (LEO)	-65 ºC to +125 ºC
Geosynchronous Equatorial Orbit (GEO)	-196 ºC to +128 °C
Trans-Atmospheric Vehicle	-200 ºC to +260 ºC
Lunar Surface	-171 ºC to +111 ºC
Martian Surface	-143 ºC to +27 ºC

Table 1. Temperature Extremes by Mission Type. Source: NASA

Fortunately, a substantial body of knowledge exists to make integrated photonics compatible with space environments. After all, photonic integrated circuits (PICs) use similar materials to their electronic counterparts, which have already been space qualified in many implementations.

Much research has gone into overcoming the challenges of packaging PICs with electronics and optical fibers for these space environments, which must include hermetic seals and avoid epoxies. Commercial solutions, such as those offered by PHIX Photonics Assembly, Technobis IPS, and the PIXAPP Photonic Packaging Pilot Line, are now available.

Takeaways

The space industry is experiencing rapid growth and commercialization, driven by technological advancements and the emergence of commercial space companies. Using multiple satellites in a constellation can enhance reliability and coverage while reducing signal disruptions.

Coherent optical technology is crucial for satellite communication links as it enables higher data rates and improve sensitivities and signal to noise ratio. The integration of electronics and optics ecosystems is essential for space certification and standardization, ensuring compatibility with the harsh space environment. Overall, addressing these challenges will continue to drive innovation and advancements in satellite communication networks.

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Tags: Amazon (Kuiper), Blue Origin, coherent, Coherent Satellite Networks, Coherent technology, communications, compatibility, cost, GEO, Global coverage, latency, LEO, LEO satellite constellations, life span, Limited bandwidth, Low latency, MEO, Networks, OneWeb, Optical communications, P2P, PHIX Photonics Assembly, PIXAPP Photonic Packaging Pilot Line, reliability, satellite, Satellite communication systems, sensitivity, Signal latency, SNR, space, Space certification, SpaceX, Technobis IPS, Telesat, Virgin Galactic

Photonic technology more available to all Industries

Insights

March 15, 2023

Coherent Optics In Space

When it started, the space race was a competition between two superpowers, but now there…

When it started, the space race was a competition between two superpowers, but now there are 90 countries with missions in space.

The prices of space travel have gone down, making it possible for more than just governments to send rockets and satellites into space. Several private companies are now investing in space programs, looking for everything from scientific advances to business opportunities. Some reports estimate more than 10,000 companies in the space industry and around 5,000 investors.

According to The Space Foundation’s 2022 report, the space economy was worth $469 billion in 2021. The report says more spacecraft were launched in the first six months of 2021 than in the first 52 years of space exploration (1957-2009). This growing industry has thus a growing need for technology products across many disciplines, including telecommunications. The space sector will need lighter, more affordable telecommunication systems that also provide increased bandwidth.

This is why EFFECT Photonics sees future opportunities for coherent technology in the space industry. By translating the coherent transmission from fiber communication systems on the ground to free-space optical systems, the space sector can benefit from solutions with more bandwidth capacity and less power consumption than traditional point-to-point microwave links.

It’s all About SWaP

One of the major concerns of the space industry is the cost of sending anything into space. Even during the days of NASA’s Space Shuttle program (which featured a reusable shuttle unit), sending a kilogram into space cost tens of thousands of dollars. Over time, more rocket stages have become reusable due to the efforts of companies like SpaceX, reducing these costs to just a few thousand. The figure below shows how the cost of space flight has decreased significantly in the last two decades.

Figure 1: The cost of a kilogram of payload into space since 2000. Source: Visual Capitalist (data from the Center for Strategic and International Studies)

Even though space travel is more affordable than ever, size, weight, and power (SWaP) requirements are still vital in the space industry. After all, shaving off weight or size in the spacecraft means a less expensive launch or perhaps room for more scientific instruments. Meanwhile, less power consumption means less drain on the spacecraft’s energy sources.

Using Optics and Photonics to Minimize SWaP Requirements

Currently, most space missions use bulkier radio frequency communications to send data to and from spacecraft. While radio waves have a proven track record of success in space missions, generating and collecting more mission data requires enhanced communications capabilities. Besides, radiofrequency equipment can often generate a lot of heat, requiring more energy to cool the system.

Decreasing SWaP requirements can be achieved with more photonics and miniaturization. Transmitting data with light will usually dissipate less than heat than transmission with electrical signals and radio waves. These leads to smaller, lighter communication systems that require less power to run.

These SWaP advantages come alongside the increased transmission speeds. After all, coherent optical communications can increase link capacities to spacecraft and satellites by 10 to 100 times that of radio frequency systems.

Leveraging Electronics Ecosystems for Space Certification and Standardization

While integrated photonics can boost space communications by lowering the payload, it must overcome the obstacles of a harsh space environment, which include radiation hardness, an extreme operational temperature range, and vacuum conditions.

*Mission Type*	*Temperature Range*
Pressurized Module	+18.3 ºC to 26.7 °C
Low-Earth Orbit (LEO)	-65 ºC to +125 °C
Geosynchronous Equatorial Orbit (GEO)	-196 ºC to +128 °C
Trans-Atmospheric Vehicle	-200 ºC to +260 ºC
Lunar Surface	-171 ºC to +111 ºC
Martian Surface	-143 ºC to +27 ºC

Table 1. Temperature Extremes by Mission Type. Source: NASA

The values in Table 1 show the unmanaged environmental temperatures in different space environments. In a temperature-managed area, these would decrease significantly for electronics and optics systems, perhaps by as much as half. Despite this management, the equipment would still need to deal with some extreme temperature values.

Fortunately, a substantial body of knowledge exists to make integrated photonics compatible with space environments. After all, photonic integrated circuits (PICs) use similar materials to their electronic counterparts, which have already been space qualified in many implementations.

Much research has gone into overcoming the challenges of packaging PICs with electronics and optical fibers for these space environments, which must include hermetic seals and avoid epoxies. Commercial solutions, such as those offered by PHIX Photonics Assembly, Technobis IPS, and the PIXAPP Photonic Packaging Pilot Line, are now available.

Takeaways

Whenever you want to send data from point A to B, photonics is usually the most efficient way of doing it, be it over fiber or free space.

Offering optical communication systems in a small integrated package that can resist the required environmental conditions will significantly benefit the space sector and its need to minimize SWaP requirements. These optical systems can increase their transmission capacity with the coherent optical transmission used in fiber optics. Furthermore, by leveraging the assembly and packaging structure of electronics for the space sector, photonics can also provide the systems with the ruggedness required to live in space.

Tags: certification, coherent, electronics, existing, fast, growing, heat dissipation, miniaturization, Optical Communication, Photonics, power consumption, size, space, space sector, speed, SWAP, temperature, weight

Insights

December 7, 2022

The Power of Integrated Photonic LIDAR

Outside of communications applications, photonics can play a major role in sensing and imaging applications.…

Outside of communications applications, photonics can play a major role in sensing and imaging applications. The most well-known of these sensing applications is Light Detection and Ranging (LIDAR), which is the light-based cousin of RADAR systems that use radio waves.

To put it in a simple way: LIDAR involves sending out a pulse of light, receiving it back, and using a computer to study how the environment changes that pulse. It’s a simple but quite powerful concept.

Figure 1: Diagram of a time-of-flight LIDAR system

If we send pulses of light to a wall and listen to how long it takes for them to come back, we know how far that wall is. That is the basis of time-of-flight (TOF) LIDAR. If we send a pulse of light with multiple wavelengths to an object, we know where the object is and whether it is moving towards you or away from you. That is next-gen LIDAR, known as FMCW LIDAR. These technologies are already used in self-driving cars to figure out the location and distance of other cars. The following video provides a short explainer of how LIDAR works in self-driving cars.

Despite their usefulness, the wider implementation of LIDAR systems is limited by their size, weight, and power (SWAP) requirements. Or, to put it bluntly, they are bulky and expensive. For example, maybe you have seen pictures and videos of self-driving cars with a large LIDAR sensor and scanner on the roof of the car, as in the image below.

Figure 2: LiDAR sensors and camera on roof of a self-driving car.

Making LIDAR systems more affordable and lighter requires integrating the optical components more tightly and manufacturing them at a higher volume. Unsurprisingly, this sounds like a problem that could be solved by integrated photonics.

Replacing Bulk LIDAR with “LIDAR on Chip”

Back in 2019, Tesla CEO Elon Musk famously said that “Anyone relying on LIDAR is doomed”. And his scepticism had some substance to it. LIDAR sensors were clunky and expensive, and it wasn’t clear that they would be a better solution than just using regular cameras with huge amounts of visual analysis software. However, the incentive to dominate the future of the automotive sector was too big, and a technology arms race had already begun to miniaturize LIDAR systems into a single photonic chip.

Let’s provide a key example. A typical LIDAR system will require a mechanical system that moves the light source around to scan the environment. This could be as simple as a 360-rotating LIDAR scanner or using small scanning mirrors to steer the beam. However, an even better solution would be to create a LIDAR scanner with no moving parts that could be manufactured at a massive scale on a typical semiconductor process.

This is where optical phased arrays (OPAs) systems come in. An OPA system splits the output of a tunable laser into multiple channels and puts different time delays on each channels. The OPA will then recombine the channels, and depending on the time delays assigned, the resulting light beam will come out at a different angle. In other words, an OPA system can steer a beam of light from a semiconductor chip without any moving parts.

Figure 2 Diagram of an optical phased array on a chip

There is still plenty of development required to bring OPAs into maturity. Victor Dolores Calzadilla, a researcher from the Eindhoven University of Technology (TU/e) explains that “The OPA is the biggest bottleneck for achieving a truly solid-state, monolithic lidar. Many lidar building blocks, such as photodetectors and optical amplifiers, were developed years ago for other applications, like telecommunication. Even though they’re generally not yet optimized for lidar, they are available in principle. OPAs were not needed in telecom, so work on them started much later. This component is the least mature.”

Economics of Scale in LIDAR Systems

Wafer scale photonics manufacturing demands a higher upfront investment, but the resulting high-volume production line drives down the cost per device. This economy-of-scale principle is the same one behind electronics manufacturing, and the same must be applied to photonics. The more optical components we can integrate into a single chip, the more can the price of each component decrease. The more optical System-on-Chip (SoC) devices can go into a single wafer, the more can the price of each SoC decrease.

Researchers at the Technical University of Eindhoven and the JePPIX consortium have done some modelling to show how this economy of scale principle would apply to photonics. If production volumes can increase from a few thousands of chips per year to a few millions, the price per optical chip can decrease from thousands of Euros to mere tens of Euros. This must be the goal for LIDAR and automotive industry.

Figure 3: Modelling of photonic integrated chip (PIC) cost as a function of aggregate number of PICs produced per year. Exponential increases in production lead to an exponential decrease in cost. Source: Model and graph provided by Prof. Meint Smit, TU Eindhoven.

By integrating all optical components on a single chip, we also shift the complexity from the assembly process to the much more efficient and scalable semiconductor wafer process. Assembling and packaging a device by interconnecting multiple photonic chips increases assembly complexity and costs. On the other hand, combining and aligning optical components on a wafer at a high volume is much easier, which drives down the device’s cost.

Using Proven Photonics Technologies for Automotive Standards

Another challenge for photonics technologies is that they need to move from into parameters and specifications in the automotive sector that are often harsher than the telecom/datacom sector. For example, a target temperature range of −40°C to 125°C is often required, which is much broader than the typical industrial temperature range used in the telecom sector. The packaging of the PIC and its coupling to fiber and free space is particularly sensitive to these temperature changes.

Temperature Standard	Temperature Range (°C)
Temperature Standard	Min	Max
Commercial (C-temp)	0	70
Extended (E-temp)	-20	85
Industrial (I-temp)	-40	85
Automotive / Full Military	-40	125

Table 1: Comparing the temperature ranges of different temperature hardening standards, including industrial and automotive/full military applications

Fortunately, a substantial body of knowledge already exists to make integrated photonics compatible with harsh environments like those of outer space. After all, photonic integrated circuits (PICs) use similar materials to their electronic counterparts, which have already been qualified for space and automotive applications. Commercial solutions, such as those offered by PHIX Photonics Assembly, Technobis IPS, and the PIXAPP Photonic Packaging Pilot Line, are now available.

Takeaways

Photonics technology must be built on a wafer-scale process that can produce millions of chips in a month. When we can show the market that photonics can be as easy to use as electronics, that will trigger a revolution in the use of photonics worldwide.

The broader availability of photonic devices will take photonics into new applications, such as those of LIDAR and the automotive sector. With a growing integrated photonics industry, LIDAR can become lighter, avoid moving parts, and be manufactured in much larger volumes that reduce the cost of LIDAR devices. Integrated photonics is the avenue for LIDAR to become more accessible to everyone.

Tags: accessible, affordable, automotive, automotive sector, beamforming, discrete, economics of scale, efficient, electronics, laser, LIDAR, phased arrays, photonic integration, power consumption, self-driving car, self-driving cars, space, wafer

Coherent technology can give free-space optical systems greater reach and capacity, enabling these new applications in space and terrestrial links.

Insights

October 20, 2022

Coherent Free Space Optics for Ground and Space Applications

In a previous article, we described how free-space optics (FSO) could impact mobile fronthaul and…

In a previous article, we described how free-space optics (FSO) could impact mobile fronthaul and enterprise links. They can deliver a wireless access solution that can be deployed quickly, with more bandwidth capacity, security features, and less power consumption than traditional point-to-point microwave links.

*Figure 1: Free space optical system diagram*

However, there’s potential to do even more. There are network applications on the ground that require very high bandwidths in the range of 100 Gbps and space applications that need powerful transceivers to deliver messages across vast distances. Microwaves are struggling to deliver all the requirements for these use cases.

By merging the coherent technology in fiber optical communications with FSO systems, they can achieve greater reach and capacity than before, enabling these new applications in space and terrestrial links.

Reaching 100G on the Ground for Access Networks

Thanks to advances in adaptive optics, fast steering mirrors, and digital signal processors, FSO links can now handle Gbps-capacity links over several kilometers. For example, a collaboration between Dutch FSO startup Aircision and research organization TNO demonstrated in 2021 that their FSO systems could reliably transmit 10 Gbps over 2.5 km.

However, new communication technologies emerge daily, and our digital society keeps evolving and demanding more data. This need for progress has motivated more research and development into increasing the capacity of FSO links to 100 Gbps, providing a new short-reach solution for access networks.

One such initiative came from the collaboration of Norweigan optical network solutions provider Smartoptics, Swedish research institute RISE Acreo, and optical wireless link provider Norwegian Polewall. In a trial set-up at Acreo’s research facilities, Smartoptics’ 100G transponder was used with CFP transceivers to create a 100 Gbps DWDM signal transmitted through the air using Polewall’s optical wireless technology. Their system is estimated to reach 250 meters in the worst possible weather conditions.

Fredrik Larsson, the Optical Transmission Specialist at Smartoptics, explains the importance of this trial:

“Smartoptics is generally recognized as offering a very flexible platform for optical networking, with applications for all types of scenarios. 100Gbps connectivity through the air has not been demonstrated before this trial, at least not with commercially available products. We are proud to be part of that milestone together with Acreo and Polewall,”

Meanwhile, Aircision aims to develop a 100 Gbps coherent FSO system capable of transmitting up to 10km. To achieve this, they have partnered up with EFFECT Photonics, who will take charge of developing coherent modules that can go into Aircision’s future 100G system.

In many ways, the basic technologies to build these coherent FSO systems have been available for some time. However, they included high-power 100G lasers and transceivers originally intended for premium long-reach applications. The high price, footprint, and power consumption of these devices prevented the development of more affordable and lighter FSO systems for the larger access network market.

However, the advances in integration and miniaturization of coherent technology have opened up new possibilities for FSO links. For example, 100ZR transceiver standards enable a new generation of low-cost, low-power coherent pluggables that can be easily integrated into FSO systems. Meanwhile, companies like Aircision are working hard in using technologies such as adaptive optics and fast-steering mirrors to extend the reach of these 100G FSO systems into the kilometer range.

Coherent Optical Technology in Space

Currently, most space missions use radio frequency communications to send data to and from spacecraft. While radio waves have a proven track record of success in space missions, generating and collecting more mission data requires enhanced communications capabilities.

Coherent optical communications can increase link capacities to spacecraft and satellites by 10 to 100 times that of radio frequency systems. Additionally, optical transceivers can lower the size, weight, and power (SWAP) specifications of satellite communication systems. Less weight and size means a less expensive launch or perhaps room for more scientific instruments. Less power consumption means less drain on the spacecraft’s energy sources.

Space military satellite, a weapon in space shoots a laser against the background of the earth. Attack, technology, space war. mixed medium, copy space. image furnished by NASA — Figure 2: Optical data transmission from a space satellite to earth.

For example, the Laser Communications Relay Demonstration (LCRD) from NASA, launched in December 2021, aims to showcase the unique capabilities of optical communications. Future missions in space will send data to the LCRD, which then relays the data down to ground stations on Earth. The LCRD will forward this data at rates of 1.2 Gigabits per second over optical links, allowing more high-resolution experiment data to be transmitted back to Earth. LCRD is a technology demonstration expected to pave the way for more widespread use of optical communications in space.

Making Coherent Technology Live in Space

Integrated photonics can boost space communications by lowering the payload. Still, it must overcome the obstacles of a harsh space environment, with radiation hardness, an extreme operational temperature range, and vacuum conditions.

The James Webb Telescope. Space Observatory for the Study of the Universe and exploration of deep space. Elements of this image furnished by NASA — *Figure 3: The James Webb Telescope. Space Observatory for the Study of the Universe and exploration of deep space*

For example, the Laser Communications Relay Demonstration (LCRD) from NASA, launched in December 2021, aims to showcase the unique capabilities of optical communications. Future missions in space will send data to the LCRD, which then relays the data down to ground stations on Earth. The LCRD will forward this data at rates of 1.2 Gigabits per second over optical links, allowing more high-resolution experiment data to be transmitted back to Earth. LCRD is a technology demonstration expected to pave the way for more widespread use of optical communications in space.

*Mission Type*	*Conditions*
Pressurized Module	+18.3 ºC to 26.7 °C
Low-Earth Orbit (LEO)	-65 ºC to +125°C
Geosynchronous Equatorial Orbit (GEO)	-196 ºC to +128 °C
Trans-Atmospheric Vehicle	-200 ºC to +260 ºC
Lunar Surface	-171 ºC to +111 ºC
Martian Surface	-143 ºC to +27 ºC

Table 1. Temperature Extremes by Mission Type. Source: NASA

The values in Table 1 are unmanaged environmental temperatures and would decrease significantly for electronics and optics systems in a temperature-managed area, perhaps by as much as half.

A substantial body of knowledge exists to make integrated photonics compatible with space environments. After all, photonic integrated circuits (PICs) use similar materials to their electronic counterparts, which have already been space qualified in many implementations.

Much research has gone into overcoming the challenges of packaging PICs with electronics and optical fibers for these space environments, which must include hermetic seals and avoid epoxies. Commercial solutions, such as those offered by PHIX Photonics Assembly, Technobis IPS, and the PIXAPP Photonic Packaging Pilot Line, are now available.

Takeaways

Whenever you want to send data from point A to B, photonics is usually the most efficient way of doing it, be it over a fiber or free space.

This is why EFFECT Photonics sees future opportunities in the free-space optical (FSO) communications sectors. In mobile access networks or satellite link applications, FSO can provide solutions with more bandwidth capacity, security features, and less power consumption than traditional point-to-point microwave links.

These FSO systems can be further boosted by using coherent optical transmission similar to the one used in fiber optics. Offering these systems in a small package that can resist the required environmental conditions will significantly benefit the access network and space sectors.

Tags: 100G, access capacity, access network, capacity, certification, coherent, free space optics, FSO, GEO, ground, LEO, lunar, Photonics, reach, satellite, space, SWAP, temperature, Transceivers

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