The optical equivalent of the well-established electronic integrated circuit (IC) is the photonic integrated circuit (PIC), which comprises a multitude of photonic components integrated into a single chip. While an electronic IC consists of transistors, resistors, and capacitors that work with electrons, PICs work with light and can embody modulators, lasers, detectors and more. Integrating various functionalities brings advantages such as extremely small footprints, high manufacturing scalability, low cost, high performance, power-efficiency, and low heat generation. Whereas PICs based on silicon waveguides have been around for more than 20 years, new material platforms were introduced in the past decade.

These new material platforms enable a new era of applications and markets and overcome the limitations of silicon in terms of propagation loss, modulation speed and wavelength coverage.

APPLICATIONS FOR PICS

PICs will play a key role in tomorrow‘s infrastructure in communication, sensing and transportation. For the quickly growing areas neuromorphic computing, augmented reality, and quantum technologies PICs are a true enabling technology.

In communication for example, the need for more bandwidth and lower power consumptions in datacom and telecom brings the existing silicon photonics to its limits. Higher modulation speeds and low loss propagation and interconnects are needed. Channel spacing will need to change from widely spaced to narrow spaced with many laser lines next to each other. Additionally, coherent transceivers will become widely spread to meet the bandwith requirements. Companies in Switzerland are developing high-speed modulators that can be integrated into a low-loss PIC platform that also enables narrow linewidth lasers for coherent telecom.

Figure 1: Artistic view of a PIC.

A vast upcoming market for PICs is the automotive industry, especially LiDAR (Light Detection And Ranging). A LiDAR device emits light to the surrounding area and detects the re”ections from objects. By measuring the time span between sending and receiving, the distance of an object can be determined. In addition to this Time of Flight LiDAR technique, Frequency Modulated Continuous Wave (FMCW) LiDAR also retrieves the speed of the object. Narrow linewidth tunable lasers together with high optical power propagation on chip and low loss for detection is needed. A PIC can integrate the individual components of traditional LiDARs such as the transmitter and even receiver, providing a one-chip solution.

Another market retains a lot of attention in PICs especially for the scaling potential is quantum sensing, communication and computing. For quantum sensing a goal is to integrate #eld sensors and detectors on a PIC to optimize weight, size, and energy e!ciency while increasing measurement sensitivity and precision by using quantum effects. On the other hand, different photonic quantum computer approaches need PICs as a photon source, the Qbit processing, and a detector. A PIC can simultaneously ful#ll the quantum computing’s need for small size, scaling to high volume and avoidance of movable parts for phase stability.

SWISS PIC COMMUNITY

Switzerland’s PIC ecosystem is ever growing. It hosts top-notch research groups at EPFL, ETHZ and PSI investigating chip-scale optical frequency combs, integrated electro-optic spectrometers based on metal-oxides, integrated quantum photonics for ion trapping, integrated plasmonics and microwave photonics. Private research at IBM Research Zurich is developing solutions for neuromorphic computing, including materials, photonic devices, and is investigating their interconnection and packaging possibilities. With LIGENTEC, Lumiphase, Polariton Technologies and Versics, there are multiple experts for design and manufacturing of PICs. Combined they offer silicon nitride (SiN), barium titanate (BaTiO3) on silicon photonics (SiPh), plasmonics on SiPh, and lithium niobate on insulator (LNOI) platforms. Deeplight, Enlightra, II-VI Laser Enterprise and Exalos provide laser modules and Vario-Optics is offering solutions for direct on-board coupling. Furthermore, CSEM is offering design, fabrication, test, and integration services, and the Swiss Photonics Integration Technology Center (Swiss PITC), a newly established entity, is to provide precision assembly and packaging solutions for micro-optical systems and PICs.

Figure 2: 200mm wafer with hundreds of silicon nitride PICs.

Figure 3: Wafer level testing of a 200mm wafer with silicon nitride PICs.

Source: https://www.ligentec.com/wp-content/uploads/2023/02/LIGENTEC-AD-SwissPhotonics-Magazine.pdf