Silicon nitride based integrated photonic 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 2x2~cm$^2$. 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 piezo electric 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. For the first time a two and three dimensional rubidium 87 MOT is realized using an active PIC. For the three-dimensional MOT, we measure $7\cdot 10^7$ atoms with a temperature of 270~$\mu$K.