【正文】 ed for optical transmission from vertical surface emitting laser (VCSEL) array to photodiode (PD) array and the builtin 45176。 waveguide mirrors are used for vertical coupling. The optical waveguide array and the 45176。 mirrors are fabricated by UV imprint process in onestep. We fabricate microlensed VCSELs by microinkjetting method, which reduced radiation angle of VCSEL from 18176。 to 15176。 for better light coupling. We use solder ball array and pin array for alignment between O PCB and the electrical subboards with alignment mismatch below 10 μm in x, y and z axis. The fabricated optical interconnection module transmits data at the rate of Gbps per channel. Keywords: Optical interconnection。 Photonic integrated circuit。 Microfabrication。 UV embossing Article Outline 1. Introduction 2. Fabrication of waveguide array and 45176。 mirrors 3. Microlensed VCSEL 4. Passive alignment 5. Optical interconnect modules 6. Conclusion Acknowledgements References 1. Introduction In the progresses of microprocessor and the inputoutput (IO) devices, the need for higher bandwidth is rapidly growing. High speed interconnects are demanding next generation IO interconnects of highly increased data capacity because today’s IO interconnects are suffering bottleneck in bandwidth at the IO interface. Many attempts to increase the IO interconnect bandwidth have emerged [1]. These attempts to extend electrical interconnect in more bandwidth manner are hard to solve fundamental problems facing the limitation of electrical properties over gigabits per channel data capacity. Operation of electrical interconnect schemes in gigabit regime will meet bottlenecks related to the properties of electrical interconnects, including material properties, skew, jitter, EMI, and power consumption. To improve the performances of electrical interconnects, many efforts in signal processing techniques such as preemphasis, equalization, multilevel signaling, and coding, deterministic jitter are needed to keep the trace of the bandwidth progress [2], [3] and [4]. Optical interconnection has a potential as an alternative approach to solve these problems because optical interconnection has many advantages over electrical interconnection such as high frequency, high bandwidth, light, immunity to EMI, low skew, low jitter, no need of ground line, easy for impedance matching. To realize an optical interconnection module for O PCB application, various photonic devices like light sources, detector arrays, and waveguide arrays are needed. The waveguides are interconnected to light sources and photodetectors in a multiple array. The 45176。 waveguide mirrors are used for interconnecting VCSEL array–waveguide array/waveguide array–PD array. Once the O PCB is designed and fabricated it has to be put together with the existing electrical circuits such as driving circuits for microlasers and microdetectors. Hence, we need microfabrication techniques for realizing optical interconnection module. We carried out microfabrication for optical interconnection module, which include design and fabrication of waveguides, coupling schemes and passive alignment. For this, we focus on the following issues: One is the concurrent fabrication of a waveguide array and 45176。 mirrors in onestep in order to reduce the number of processing steps for lowcost production and another is a method to improve coupling efficiency between VCSEL array–waveguide array/waveguide array–PD array including the passive alignment method between the different parts of the optical interconnection module. This paper demonstrates a microfabrication of optical interconnection module to be used for the realization of optical printed circuit board (OPCB) [7] and [8]. 2. Fabrication of waveguide array and 45176。 mirrors To use polymers as materials of the waveguide, embossing technique is used because of its relatively easy fabrication process. We fabricated polymer waveguides by UV embossing, which also involves fabrication of mold and replica. UV curable polymers are used as materials of waveguides and silicon mold is used to form waveguide patterns. For vertical coupling between VCSEL array and waveguide array and between the waveguide array and the PD array, we have to utilize mirror face at each end of the waveguide. To achieve this process, waveguide mold equipped with 45176。 faces at each end of the mold is needed to form the vertical coupling structure in a single fabrication step. We made a 12 channel silicon waveguides mold, which has 45176。 mirror face at the ends of each waveguide. The dimension of the waveguide is 50 μm width and 50 μm he