To meet the increasing demand for board level high speed data transmission in the area of high performance computing, much attention has been paid to employ high performance polymer optical waveguide. So far, optical interconnects have been considered to have advantages over electronic solutions in various aspects, such as lower power consumption, larger information carrying capacity and immunity to crosstalk. It is one of the advantages that waveguides are possible to be curved and crossed light paths in the same circuit plane. GI-core polymer waveguides are capable of confining the signal light around the core center more tightly, by which the GI-core waveguides exhibit low propagation loss, low crosstalk, and low modal dispersion. Therefore, GI-core reduces the loss in meshed waveguide compared to SI-core meshed waveguides. The material of our GI-core polymer waveguide is Polynorbornene. The varnish for both core and cladding is prepared and coated onto a substrate then the coated layers are exposed to a UV light through a photomask and heated at a certain temperature. After heating, index profile changes and GI-core waveguide is formed. This is our original photo-addressing method. We confirm that extremely low crossings loss is observed in both 90-degree (0.53 dB/500 crosses) and 45-degree (1.55 dB/500 crosses). Also, we succeed high-speed data transmission. We expect that this ultra low crossing loss GI-core waveguide will be one of the promising components giving a strong impact on high performance computing systems in near future.