nanoTHz-TDS

brings terahertz imaging and spectroscopy to the nanoscale

neaspec nano-THz Time Domain Spectroscopy combines s-SNOM probing principle with Time Domain Spectroscopy (TDS) system. nano-THz TDS provides far-IR spectroscopy and imaging at the spatial resolution of AFM, enabling nanoscale profiling of free carrier density in semiconductors and vibrational nanoscopy in nanostructured samples.

Challenge

Due to combination of relatively low power output of THz TDS (ca. tens of microwatts) and scattering efficiency of commercial AFM tips-antennas, nanoscale THz-TDS requires careful design with minimum transmission losses and maximum collection efficiency.

Solution

neaspec nanoscale THz-TDS systems are equipped with patented dual-beam parabolic mirror, which allows for separating illumination and collection channels without beam-splitter or isolators, thus minimizing transmission losses and maximizing collection efficiency of weak nanoscale THz signal. Dedicated THz emitter/receiver design ensures precise on-axis alignment for maximum effective bandwidth, which in combination with integrated pump and delays, delivers reliable turnkey THz spectroscopy and imaging at the nanoscale.

neaspec THz-TDS generated and detects THz field using a pair of emitter and receiver antennas that are carefully aligned with the optical axes of a patented dual-sided parabolic mirror. The mirror focuses THz light onto the AFM tip with one side and collects the scattered THz light by another side to provide a dedicated detection channel without use of beam splitter, which would result in additional losses. To facilitate the generation and detection of the THz radiation, the antennas are pumped by short femtosecond near-IR pulses from an integrated high-repetition rate source. An integrated optical delay line allows for sampling of the scattered THz field as a function of time, which delivers near-field THz spectroscopy upon the Fourier transformation or rapid sample screening upon scanning the sample at a fixed delay. 100% suppression of far-field background is achieved by high-harmonic demodulation typical in s-SNOM. Complete integration of all hardware and software components ensures reliable user-friendly turnkey operation.

Technology Benefits

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Amplitude- and phase-resolved nano-spectroscopy for complete characterization of sample complex dielectric function.

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Nanoscale imaging with spatial resolution ~20 nm (l/12000) across the whole THz range.

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Capability for quantitative nanoscale free carrier profiling without tedious calibration.

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Amplitude- and phase-resolved THz hyperspectral imaging for complete sample characterization at the nanoscale.

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High quality THz imaging and spectroscopy from ambient conditions down to cryogenic temperature <10K.

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Custom THz pump-probe experiments for nanoscale investigation of carrier dynamics.