Fig. 5: Low voltage fast tuning with integrated PZT piezoactuator.
From: Low-noise frequency-agile photonic integrated lasers for coherent ranging
a False-coloured SEM image of the sample cross-section, showing the PZT actuator integrated on the Si3N4 photonic circuit. The piezoelectric actuator is composed of Pt (yellow), PZT (green) layers on top of Si3N4 (blue) buried in SiO2 cladding. b Optical micrograph of disk-shaped PZT actuator on top of Si3N4 microring with 100 GHz FSR. c Frequency excursion as a function of the voltage applied to the PZT actuator, measured at 81 kHz triangular chirping rate. Linear fit (red) provides 520 MHz/V tuning efficiency. d Time-frequency spectrogram of the heterodyne beat-note for 500 kHz triangular chirp repetition frequency with 1.1 V applied to the PZT actuator. e Residual of least-squares fitting of the time-frequency trace with symmetric triangular chirp pattern.
