Broadband microwave-to-terahertz near-field imaging

In this paper we present a high performance near-field imaging method suitable for broadband applications. Recent advances in preparing micrometer and submicrometer resolution near-field probes are reported, along with examples of applications of this method both for frequency and time domain measurements. For the latter, pulsed terahertz radiation has been used to probe a broadband (300 GHz-2 THz) spectroscopic response of substances with different dielectric properties. For frequency domain measurements a continuous wave 80 GHz radiation has been applied to metallic, semiconducting, ferroelectric and biological objects. Frequency independent high spatial resolution and high sensitivity have been demonstrated for all measurements.