Silicon nitride-based photonic integrated circuit to control a cold atom source

We have developed a silicon nitride-based photonic integrated circuit (PIC) that is responsible for the cooling, pumping, and imaging of cold rubidium 87 atoms. The photonic integrated circuit consists of two chips placed next to each other and has a total area of 2 × 2 cm2. This greatly minimizes the area needed while still having all the optical control functions to create, control, and measure a magneto-optical trap (MOT). The piezoelectric material lead zirconate titanate (PZT) on the PIC is employed for phase shifting a Mach–Zehnder-type configuration where extinction ratios up to 50 dB and switching speeds of 1 MHz are achieved. This resulted in the realization of two- and three-dimensional rubidium 87 MOT using an active PIC. For the three-dimensional MOT, we measure 7·107 atoms with a temperature of 270 μ K.