sSNOM Upgrade for University of Manchester

Description

Upgrade enabling time-resolved pump-probe spectroscopy for cryogenic THz-TDS near-field measurements. The pump laser must be synchronized with the existing THz-TDS spectroscopy and cryogenic near-field systems. The upgrade includes a laser amplifier unit with free-space coupled optical output at 780nm, 100MHz rep rate, pulse energy >1.3nJ, >140mW output power, and customized fiber patch cord for temporal overlap of pump-probe pulses. Additionally, a transmission module enables static pump-probe measurements in transmission, where the sample is pumped via a diffraction-limited beam from the bottom and probed by amplitude- & phase-resolved near-field measurements (pseudo-heterodyne detection) from the top. Lot 1: Upgrade for cryo-neaSCOPE+xs s-SNOM system can only be provided by the base system’s manufacturer – attocube systems AG. Needs and requirements include: 1. Ultra-fast spectroscopy software module for THz-TDS • Enables pump-probe spectroscopy for THz-TDS in neaSCAN • Provides software control of all delays and components for ready-to-use results • Allows acquisition of time-resolved spectra with down to 40 fs temporal resolution 2. Synchronized Transmission-Mode Detection Module • Enables bottom-side sample illumination in transmission-mode with broadband parabolic mirror (NA=0.44) • Enables simultaneous detection of optical near-field amplitude & phase • Motorized parabolic mirror for beam-alignment • Stationary focal point with respect to AFM-tip • Variable illumination spot size (ca. 2μm - 100μm) • Suitable for plane-wave illumination • Exchangeable beam-splitter mount • Supports stationary focal point with respect to sample position (bottom-side illumination synchronized with sample scanner) • Support AFM scan-speed: up to 20 μm/s @ highest spatial resolution 3. Software Development Kit for neaSCAN 4. THz Pump-Probe operation • additional delay line & synchronized software control for pump probe • amplifier unit with free-space coupled optical output at 780nm with amplifier unit mounted on optical table next to neaSNOM microscope • 100MHz rep rate, pulse energy >1.3nJ, >140mW output power • Customized fiber patch cord for temporal overlap of pump-probe pulses