Abstract

Electro-Optic (EO) probing is a technique that enables the monitoring of very fast electric signals, up to several TeraHertz (THz). It is based on the Pockels effect, which enable an EO crystal subjected to an electric field to modulate a light beam travelling through it. The low invasiveness, very wide bandwidth and great spatial resolution of this technique make it a successful candidate for various applications, such as THz pulse detection or high-speed systems characterisation [1,2]. Two popular approaches are EO sampling (based on a pulsed laser), which makes use of light pulses to sample a high-frequency signal, and heterodyne EO (based on a continuous-wave laser), which uses the EO probe as a mixer to down-convert a RF signal to an intermediate frequency signal which can be processed more conventionally. However, both approaches exhibits shortcomings, such as the need for very accurate synchronisation of THz and laser pulses in EO sampling systems, or the limited bandwidth of heterodyne set-ups [3]. Here we propose a novel, hybrid EO probing system which combines the best of both worlds, potentially allowing to reach THz frequencies using a continuous-wave laser and a photonic-generated local oscillator (LO).

© 2015 IEEE