Milliwatt-level THz power scaling in fiber-coupled THz TDS enabled by 1GHz dual-comb laser

We present a terahertz (THz) time-domain spectrometer (TDS) achieving record emitted THz power of up to 1.5 mW with state-of-the-art, fiber-coupled antennas. This performance is enabled by a solid-state Yb:CALGO dual-comb laser with a spatially multiplexed cavity and reflective biprism, generating two modelocked pulse trains at 1 GHz with ultra-low-noise characteristics. An optical parametric oscillator converts the 1057 nm output to 1550 nm for optimal antenna operation. Advanced antennas, fabricated from ultrafast, rhodium-doped InGaAs photoconductors grown on InP, serve as both emitter and receiver. A dispersion-compensating fiber is used to compresses the optical pulses to 120 fs, yielding >4 THz bandwidth and up to 80 dB dynamic range. These results establish repetition rate scaling with gigahertz dual-comb lasers as a promising route for high-performance fiber-coupled THz TDS.