Figure 1. Spatial multiplexing scheme.

A single laser is coupled to a monolithic silicon chip to pump an ultra-compact array of silicon PhCWs. Photon pairs are generated in the PhCW region, wavelength separated by integrated arrayed waveguide gratings (AWGs) and the heralding photons detected using single photon detectors. The remaining photons go through a delay line, while a fast electronic logic gate sets the state of the PLZT switch. The selected heralded photon is then routed to the common fibre output. The orange box region represents the experimental setup for results presented in this work. Inset: our first implementation used a device with two separate but monolithically fabricated PhCWs, designated A₁ and B₁.