April 14,2025, One of the most important innovations at this year's GTC must be CPO. Anyone who has seen the CPO demonstration on the GTC showfloor will surely be impressed by the 18 external lasers, whose size even exceeds that of an 800G optical transceiver. If we assume that OFC is deliberately scheduled after GTC, then I think there must be special considerations for inviting Professor Kei May Lau from the Hong Kong University of Science and Technology to give a speech on the integration of silicon-based technology and III-V materials in the Keynote session of this year's OFC.
In the field of display, the Micro-LED optical engine technology and products developed by Professor Lau's team have already achieved great success in terms of performance and mass production.
With Professor Lau on OFC Reception party
In recent years, they have also developed a technology for manufacturing III-V DFB lasers on SOI wafers related to optical communication. Their 1.5-micron DFB lasers can be configured coplanarly with the silicon layer, enabling efficient cooperation between the III-V lasers and silicon waveguides. If this technology can succeed, the CPO solution seen at GTC this year may look quite different.
At this year's OFC, the editor also received an invitation from a European foundry, X-Fab, they want to talk about their technology on integrating III-V semiconductor lasers on silicon materials. At the X-Fab booth, the gentleman who received the editor was Mr. Joni Mellin, the Business Line Manager of X-Fab. He is from Finland and used to work for Nokia, so he is very familiar with the communication industry. He told the editor that this is the first time X-Fab has participated in the OFC exhibition this year, but it is an established foundry with a history of more than 30 years, with an annual sales volume of over 800 million euros. It has six foundry factories around the world, three in Germany, one in France, one in the United States, and one in Kuching, Malaysia, with a total of more than 4,500 employees. X-Fab may not be very familiar to us who are engaged in optical communication, but it is already a world leader in the fields of analog mixed-signal ICs, MEMS, and GaN chip manufacturing. Its business covers many fields such as automotive, medical, consumer electronics, and communication.
Before this year's OFC, X-Fab, together with Smart Photonics in Denmark and Epiphany Design in the Netherlands, jointly demonstrated an InP on SOI solution for optical transceiver applications based on MTP (Micro-Transfer-Printing). Their goal is to launch sample products next year and achieve mass production by 2027.
With Mr. Mellin at X-Fab's booth
What is MTP technology? Mr. Mellin told the editor that this is a heterogeneous integration technology developed by X-Celeprint in Ireland, which has been used in many fields such as LED display for many years. The key to this technology is the so-called Elastomer Stamp, whose structure is a thin layer of silicone supported by quartz glass, and it was initially used for the batch picking up and releasing of Micro-LEDs. According to the website of X-Celeprint, the MTP technology can quickly and precisely assemble micro-components from various different source materials onto non-native target substrates (such as glass, plastic, ceramic, and silicon). The retrievable micro-components are picked up by an elastomer stamp and printed onto the target substrate with a yield exceeding 99.9%. Devices that combine GaN, GaAs, InP, and other compound semiconductor materials are successfully integrated onto silicon and glass with fine precision to manufacture highly integrated compound semiconductor microsystems.
Chiplets printed on a 8 inch Wafer
Mr. Mellin picked up their wafers and patiently explained to the editor how they printed the III-V chips onto the silicon SOI substrate. They have already integrated the lasers, detectors, modulators, driver chips, etc. together, and can support more precise alignment with the waveguides. Mr. Mellin said that compared with the Micro-LED application, the difficulty of optical communication applications lies in the higher precision requirements. For example, the previous precision was 1 micron, while for optical communication, it needs to be below 0.5 microns. X-Celeprint said that they can already achieve a precision of 200nm.
Before this, the editor had seen the PWB technology of Germany's Vanguard and the DOW technology of South Korea's Lessengers, which are printing-based technologies for optical waveguide manufacturing. Now, not only waveguides but also lasers can be printed. If this technology can eventually succeed, we will witness a greater transformation in the optical communication industry, not just the CPO demonstration seen at GTC this year.
