150 GS/s real-time oscilloscope using a photonic front end

We demonstrate an optical front end technology that multiplies the sampling rate of a real-time oscilloscope by a factor of three. Our approach uses an optical pre-processor to compress the signal bandwidth of continuous-time high speed RF waveforms. To operate in continuous-time mode, the optical signal, which carries the RF, must be segmented and demultiplexed into an array of N parallel channels. In prior work, large spectral overlap between channels was needed for calibration and this limited the multiplication factor, M, to values far below the maximum value of N, which is limited by the number of back-end digitizers. In this paper, we demonstrate a novel technique using temporal overlap between channels and achieve higher multiplication. The sampling rate of a four-channel 50 GS/s real-time oscilloscope is increased by a factor of 3, enabling us to digitize a 47 GHz tone at 150 GS/s. To our knowledge, this is a record in continuous time RF digitization.