Low‐Harmonic Generation in Cascaded Thin‐Film Lithium Niobate Waveguides
Tracy Sjaardema, Marcin Malinowski, Ashutosh Rao, Sasan Fathpour
Abstract
Herein, frequency conversion to the third‐ and fourth‐order harmonics are demonstrated in ultracompact cascaded periodically poled thin‐film lithium niobate (LN) waveguides on silicon substrates. Pumped at 1550 nm wavelength, the tightly confined waveguides produce strong third‐ (523 nm) and fourth‐harmonic (386 nm) signals. Actively monitoring the periodic poling process on the LN devices renders these efficient frequency conversions. Measurements with a femtosecond pulsed laser source result in comparable power levels across the generated harmonics. A model that simulates harmonic generation from the pulsed source is presented and discussed. The model's results are in general agreement with the experimentally observed processes.