MANY IN ONE: This is an Illustration of a system-on-package test bed that combines three types of circuits in its dielectric layers: an optical circuit—with waveguide and detector just beneath the surface; RF thin-film components—resistors, inductors, and antennas, embedded within the package; and digital thin-film components—low-loss dielectrics, low-resistance conductors, and decoupling capacitors—at the bottom. In addition, a variety of bare and packaged devices, including flash memory, microprocessor, system-on-chip (SOC), the optical circuit's gallium arsenide laser diode, MEMS, and system-in-package (SIP) devices can be attached to the top layer. Global interconnections on the surface connect the top devices to the layers, which are deposited on a thin but stiff inorganic composite substrate.