Electro-optical co-integration of chip-components in optical transceivers for optical inter-chip communication

This paper discusses a novel packaging approach for electro-optical (E/O) co-integration of IC-chips to realize hetero-integrated transceivers for optical chip-to-chip (C2C) communication. For an integration of chip-components into optical transceivers a polymer package fabricated using additive manufacturing methods are applied. Based on two optical transceiver assemblies - VCSEL-based and Si-photonic-based - different requirements on the package are discussed. For the Si-photonic chips measurements on the lateral and angular misalignment requirements have been performed. The results of the characterization of grating couplers show that the maximum lateral misalignment for 1dB-loss vary between ± 1 µm and ± 3.5 µm. For the angular sensitivity the 1dB-tolerances of +/- 2° at the in-coupling interface and of about +/- 0.4° at the out-coupling have been measured. The simultaneous IC-device embedding and chip-carrier fabrication using casting method is proposed. By subsequent build-up of dielectric/metal multilayer stack an electrical and optical redistribution network for routing of both optical and electrical signals can be realized. A hybrid polymer Ormocer® material has been applied as optical and dielectric material enabling the E/O co-integration using one material class. The performance of this material in both domains optical and RF has been proven. Based on attenuation measurements of multimode optical waveguides low-loss transmission of < 0.05 dB/cm at 850 nm wavelength has been shown. Based on transmission-line (TL) measurements in the frequency range of 140 GHz to 220 GHz the superior dielectric properties with TL-losses of about 1.1 dB/mm have been achieved.