PIC Magazine Technical Editor Mark Andrews spoke with company co-founder Michael Geiselmann about its technology, fast turnaround and unique capabilities for corporate and research partners that are developing or exploring new photonic devices for wide-ranging applications. LIGENTEC was founded in 2016 and grew out of work that began in 2011 at the École polytechnique fédérale de Lausanne (EPFL), which is one of the two federal polytechnic university branches in Switzerland.

LIGENTEC (Lausanne, Switzerland) focuses on silicon nitride (SiN) for photonic integrated circuits (PICs). Amongst its many advantages, SiN is extremely well suited for maintaining very low waveguide propagation loss, which is of special interest within integrated quantum photonics, bio-sensing, LiDAR, supercontinuum and pulse generation, as well as applications that include high Q-filters, spectroscopy, and microwave photonics. The company was recognized with a 2018 PIC Award for corporate development of innovative photonic integration materials, processes and services.

As Geiselmann explained, the laboratory was developing integrated platforms with high quality resonators for nonlinear photonic applications including frequency comb generation prior to LIGENTEC’s formation. Geiselmann said these platforms started to attract a lot of interest for use in a variety of applications, so the co-founders decided to investigate the possibility of scaling up the process to make it commercially viable and offer it to researchers and the wider commercial photonics industry. He added that making the leap from lab to fab was made possible thanks to substantial commitment from Dr. Michael Zervas, another LIGENTEC cofounder, who brought his experience from Oerlikon, IBM and Intel to the Swiss startup. These abilities proved crucial in addressing commercial requirements and grappling with the many requirements new companies have to meet once they begin offering products and process solutions to commercial enterprises.

LIGENTEC provides a complete low loss platform based on thick film stoichiometric LPCVD silicon nitride with a turnaround time of two months. For those who don’t regularly work with fabs, this is fast—Geiselmann explained that LIGENTEC’s typical turnaround is two to three times faster than other foundries. LIGENTEC’s high confinement waveguides enable a decrease in chip size by a factor of four as bends can be as small as a few tens of micrometres. The complete platform includes a process design kit (PDK) with verified designs and a fully configured software environment.

Getting to know LIGENTEC, one hears ‘thick waveguides’ a lot because even while the foundry delivers devices much faster that others, their focus on very thick materials deposition is a stand-out advantage.

“The advantages of propagating light in thick film SiN are multifold. With a thick waveguide material the optical mode is almost fully confined in the waveguide material. This allows having very small bends in the PIC design (important for AWGs, delay lines or small ring resonators), which reduces footprint, increases yield and thus reduces cost. Furthermore, high optical power of several Watts can be propagated in thick film SiN without damage to the PIC; the propagation losses decrease with the high mode confinement, which removes the need for amplification in complicated PIC designs. Last but not least the thick film SiN material offers the possibility to engineer dispersion of the waveguide and the benefit of using nonlinear properties such as two-photon generation for quantum communication,” Geiselmann explained.

LIGENTEC’s silicon nitride small footprint AWGs, phase shifters and splitters for telecom SiN platform. Image by Belen Lopez-Fuchet, LIGENTEC

Since its inception, the company has focused on meeting design and product development needs across the supply chain while maintaining their connection to photonic researchers and R&D facilities across Europe and other centers of photonic excellence.

“LIGENTEC customers are large corporations as well as smaller, high-tech companies and R&D centers. The low propagation loss of our SiN-enabled devices, together with high power level operation makes the platform unique for market areas such as laser metrology, microwave photonics, LiDAR, AI and 5G. The possibility to generate photon pairs on the chip together with the low propagation loss is very interesting for quantum applications. The large transparency window from the visible to the mid-infrared allows a SiN-based PIC to enter markets in bio sensing and gas-sensing,” he added.

Beyond the flexibility of working with a company built to serve organizations of all sizes, Geiselmann said they continue to appreciate that while some customers are large, many are SMEs and customers also include research organizations that work with limited budgets.

“LIGENTEC offers an all-nitride-core foundry service with a fast turn-around time. There are two standard processes specifically engineered for customer applications in the visible and the IR, with their respective PDK and process modules. This enables a fast prototyping of the desired PIC-based product. Furthermore, LIGENTEC offers a low-cost access to the all-nitride-core technology using the cost sharing model of multi-project wafers (MPW.) The platform can provide low propagation loss PICs (<0.1dB/cm) and is transparent from the visible to mid-infrared (400nm-4000nm). LIGENTEC is fully committed to offer a platform forging strong partnership agreements with key players in the photonic ecosystem, providing our customers with the entire validated supply chain,” he said.

Low loss compact delay lines with losses below 5dB/m. Image by Belen Lopez-Fuchet, LIGENTEC

As an exciting new branch within the global photonics industry, PIC device designers and manufacturers are still working through the processes of taking their designs and products from low-level, manual assembly and test to higher production levels including packaging pilot lines. Most companies across the industry agree that standardized test, assembly and packaging (TAP) is a goal all can support since achieving it will help ensure quality and reduce device failures in the field, as well as help achieve the cost objectives of datacom, telecom and other price sensitive customers. Geiselmann explained that while LIGENTEC is not yet packaging devices in-house, they have established a qualified partner network and are ever mindful of the need, supporting local and industry-wide efforts to standardize and automate operations.

“LIGENTEC takes reliability and quality assurance as a top priority for large scale adoption of PIC. To that end we are enhancing our effort on statistical control of our models and are establishing collaboration agreements with research centers to stress-test our components in all relevant environments. For example, SiN resonators were exposed to proton radiation for space applications. LIGENTEC passive circuits have a very low failure rate due to dedicated development and testing of the PDK.”

“LIGENTEC’s SiN platform offers spot size converters that make packaging to SMF28 fiber very efficient. Furthermore, LIGENTEC’s platform offers the capability to have several SiN layers implemented to enable 3D photonic integrated circuits. Furthermore LIGENTEC chips can be operated as interposer chips with record low loss coupling levels for hybrid integration,” he said. LIGENTEC is already looking at ways to enhance its portfolio and as it works more with customers is addressing unique needs as well as working to satisfy requirements within long-established applications.

“LIGENTEC has developed a PDK for telecom wavelength and visible wavelength for bio-sensing and microsopy. Additional modules are available to integrate metal layers for phase shifters and switches as well as cladding opening for bonding other PICs or sensing applications. LIGENTEC operations are based on industry standards of using SPC and Cp, Cpk to control process performance. Our processes come with a rigid set of quality control to ensure guaranteed geometric accuracy and high performance. In addition to that we actively invite our customers to influence our R&D roadmap to develop a technology portfolio that is market relevant,” Geiselmann added.

AWG for visible wavelength operation for LIGENTEC’s visible SiN platform. Image by Belen Lopez-Fuchet, LIGENTEC

For further information about the advantages of silicon nitride (SiN) based PIC component design and foundry services, visit the company website at, or email them at: