"Optical Pin" played a major role in the realization of optical I/O cores. Originally, in 2005, Tokai University Professor Osamu Mikami (now a Guest Professor) proposed a concept of an optical pin fabricated by Self-Written Waveguide Technology with Mask Transfer Method using UV curable resin. "Optical Pin" is a transparent optical pillar (a kind of vertical waveguide) whose diameter/height can be freely and easily customized based on customer needs. Typical dimensions are 50 µm in diameter, and 50-500 µm in height.
Photonics Electronics Technology Research Association (PETRA, http://petra-jp.org/) paid attention to this technology, and proceeded with research and development under the technical supervision of Prof. Mikami. AIO Core Co., Ltd., (www.aiocore.com), newly established from PETRA, achieved the commercialization of optical I/O through utilization of this new technology. The production line is now scheduled for full-scale mass production.
With the advancement of AI and IoT, the traffic volume of electronic information is increasing at an ever-accelerating rate, with greater amounts of information required to be processed in a shorter time. There is a serious problem in transmission amounts and speed between LSIs, memories, switches, and so on. In a bid to solve this problem, there has been intense competition for development of optical technology all over the world. An optical transceiver that converts electrical signals to optical signals and optical to electrical is one of the key devices in this optical wiring. Development of an on-board optical module that can be mounted in the vicinity of an LSI on an electronic circuit board has long been demanded.
New Energy and Industrial Technology Development Organization (NEDO) and PETRA developed the smallest on-board optical module (34mm x 36mm x 8mm), realizing 400Gbps transmission speed for the first time in the world. 4pcs optical I/O cores, which are chip scale 100Gbps optical transceivers, are built in the on-board module. One of the key technologies applied to optical I/O cores is Optical Pins. The optical I/O core uses an Optical Pin that can control the beam size at the input/output part of the light, so that alignment tolerance of about 10 µm is achieved at the junction with the multi-mode fiber, as schematically shown in Fig.1. This innovative technology has drastically improved the optical axis alignment resulting in realization for mass production. Optical and electrical I/Os are fabricated on silicon photonics integration chips. 4 to 10 optical pins (depending on the number of channels) with a minimum pitch of 125 µm are fabricated using a photolithography technique (Mask Transfer Method) using UV curable resin, as shown in Fig. 2.
This innovation from Tokai University has now come of age for commercialization. Optical Pin is a valuable example of a success that has taken off in the real world.