We discuss recent progress in miniaturizing terahertz devices, facilitated by integrated photonic circuits. We show these provide ways to engineer dispersion, achieve field enhancement and realise complex functionalities on a single chip.

We present emission up to 3 THz from a phase-matched terahertz-optical photonic circuit, featuring a co-planar metallic cavity traversed by an optical rib waveguide and a dipolar antenna for efficient out-coupling of terahertz waves.

Terahertz science and technology is possibly now at an inflection point where integrated photonic circuits become increasingly viable sources and detectors of such high-frequency radiation. Generation in both second order [1] and third order [2,3,4] nonlinear waveguides and architectures thereof has exploited either optical rectification or microcomb generation with subsequent optical-to-terahertz conversion at a uni-travelling carrier photodiode. These initial demonstrations showcase a possible route towards miniaturized terahertz chips that are seamlessly integrated with photonics.