RF 3D Assembly for High Density Photonic Circuits

In this contribute we present the design of an innovative 3D RF interposer for high-density photonic integrated circuits (PICs). This 3D interposer has been designed to operate at frequencies up to 50GHz for applications exploiting 64GBaud/s modulations. An AlN substrate has been used for the fabrication and has been mounted with flip-chip technology and solder bumps reflow; a prototype using the proposed interposer and a high-speed amplitude modulator InP chip has been assembled to validate the approach and the simulations. The use a 3D interposer allows to ease the layout and to increase the photonic integration scale by managing the RF tracks routing outside the optical chip without impairing the performance; moreover, the interposer avoid proximity between the power-hungry high-speed electronics and the optical chip, resulting in a greatly reduced thermal crosstalk between these components and the optical chip.