In today’s digital world, the demand for high-bandwidth data transmission is increasing dramatically. The explosive growth of artificial intelligence (AI), machine learning (ML), quantum computing, LiDAR technology, and cloud-based applications is constantly pushing the boundaries of current data transmission technologies. Optical transceivers on the market today provide data rates of 800 Gb/s and 1.6 Tb/s using existing photonic materials, but complexities and potential limitations are being identified leading to the emergence of new technological approaches. He enters Thin-film lithium niobate (TFLN) – A promising solution aimed at achieving high data transfer rates with the added advantage of reduced power consumption.
What is thin lithium niobate (TFLN)?
Thin-film lithium niobate, abbreviated as TFLN, is an advanced material that leverages the superior electro-optical properties of lithium niobate in a thin-film form. By attaching a thin layer of lithium niobate to a substrate such as silicon dioxide or sapphire, TFLN combines the best of both worlds.
Lithium niobate has one of the highest photovoltaic coefficients among photovoltaic materials, enabling efficient modulation and a high photovoltaic coefficient. Its thin-film approach allows for smaller, more integrated optical components in a compact form factor. Finally, TFLN can provide low optical losses while operating at higher transfer speeds exceeding 1 TB/s.
What potential challenges to conventional silicon photonics does TFLN address?
The mainstream chip technology approach used for up to 800 Gbit/s along with some new 1.6 Tbit/s optics, silicon photonics has been instrumental in the rapid advancement of high-speed, high-bandwidth optical communications. Industry experts and reports expect this to continue as silicon photonics will continue to play a dominant role in optical transport for the foreseeable future. However, as companies strive to deliver 1 TB/s or more, silicon photonic technologies face some known limitations and challenges to achieve this efficiently.
Silicon material properties limit its ability to support higher modulation speeds without significant signal degradation, resulting in bandwidth limitations. Modulation in silicon photonics faces a limitation on electron mobility, a fixed physical limit. Therefore, silicon photonics cannot exceed a modulation rate of 50 GHz (equivalent to 200 GHz with PAM4 modulation), so achieving higher data rates of 800 Gbit/s, 1.6 Tbit/s, etc. requires more of parallel channels, which adds complexity as well as increased power consumption and dissipation. .
In terms of power consumption, achieving higher data rates using this approach means more power is needed, making solutions less power efficient as data rates increase. As with most systems and devices, higher power consumption results in increased heat generation, complicating thermal management with a potential impact on performance. Finally, the necessity of integrating more active and passive components on a silicon substrate leads to greater complexity at higher frequencies and for manufacturing purposes.
Benefits of TFLN
The use of TFLN technology has been shown to successfully address some of the limitations of silicon photonics. The key entities and players driving this developing technology all seem to agree on some of the stated advantages of TFLN:
Ultra-High Bandwidth: TFLN rates can achieve modulation speeds exceeding 100 GHz, supporting data rates exceeding 1 TB/s.
Significant power saving: Greater modulation efficiency reduces the power required for high-speed data transmission, resulting in significant power saving. While the total power consumption of a transceiver module involves multiple elements (transmitters, receivers, drivers, and service providers), it has been demonstrated that a TFLN can operate at a CMOS-compatible voltage of 1-1.2 V, driven by CMOS electronics. (In comparison, silicon modulators require a driver to power the modulator and operate in the 3-4V range)
Improved thermal performance: Lower power consumption translates into less heat generation, simplifying thermal management.
Scalability: The thin-film nature of TFLN allows for improved integration with existing semiconductor processes, facilitating mass production.
TFLN Company Spotlight – Lightium AG
Similar to most promising technologies, multiple entities around the world are focused on advancing TFLN technology by designing and manufacturing TFLN components and solutions. While US-based HyperLight remains a recognized leader in the TFLN space primarily manufacturing packaged modulators, other new entities are also entering the TFLN arena. The optimism from the investment community is all supported, which is a positive sign of growth and confidence in the TFLN technology market as a whole.
One such company is Lightium AG, a Switzerland-based company that was founded just one year ago in September 2023. In the past few months since May 2024, Lightium has received a nearly $3 million grant from InnoSuisse, along with a new seed round this month in September 2024 In the amount of 7 million US dollars. The company, an entity that provides foundry and design services to TFLN, offers production-level prototyping by manufacturing large quantities of 200mm CMOS-compatible wafers.
“Lithium niobate processing is known to be extremely challenging. At Lightium, we have now developed the manufacturing capacity to make this technology available at scale to industry. What was previously limited to academic clean rooms and R&D rooms is now an accessible reality for industry to adopt.” “, says Dr. Amir Ghadimi (PhD), CEO and Co-Founder of Lightium.
Thin-film lithium niobate – a promising technology
As critical demand for optical transceivers delivering 1 Tb/s and beyond continues to grow rapidly in the coming years, TFLN is beginning to establish itself as a technology with the potential to play an important role in paving the way to achieving these levels of performance. Besides supporting higher bandwidth levels, the power savings that can be achieved through the use of TFLN is another attractive feature, given the expected volumes of devices expected to be deployed in networks around the world amid rising power consumption concerns.
