Broadband terahertz wave generation from a MgO:LiNbO_3 ridge waveguide pumped by a 15 μm femtosecond fiber laser

Cherenkov phase-matched terahertz (THz) wave generation from a $\mathrm{MgO}\text{:}{\mathrm{LiNbO}}_3$ ridge waveguide was studied using optical rectification. Pumping was achieved using 20 and 60 fs laser pulses from a fiber laser centered at 1.56 μm. Time-domain spectroscopy (TDS) results showed a single-cycle pulse with 20 fs pulse pumping and a near-single-cycle pulse with 60 fs pulse pumping. The spectrum covered the range of 0.1–7 THz, with a signal-to-noise ratio of over 50 dB. The output power measured by a Si bolometer and a deuterated triglycine sulfate pyroelectric detector is shown and compared to that of a commercial photoconductive antenna. This system is believed to be a promising THz source for low-cost, compact, robust, and highly integrated TDS, THz imaging, and tomography systems.