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Broadband pump-probe spectroscopy at 20-MHz modulation frequency

2016; Optica Publishing Group; Volume: 41; Issue: 13 Linguagem: Inglês

10.1364/ol.41.002970

1539-4794

Fabrizio Preda, Vikas Kumar, Francesco Crisafi, Diana Gisell Figueroa del Valle, Giulio Cerullo, Dario Polli,

Spectroscopy and Quantum Chemical Studies

We introduce an innovative high-sensitivity broadband pump-probe spectroscopy system, based on Fourier-transform detection, operating at 20-MHz modulation frequency. A common-mode interferometer employing birefringent wedges creates two phase-locked delayed replicas of the broadband probe pulse, interfering at a single photodetector. A single-channel lock-in amplifier demodulates the interferogram, whose Fourier transform provides the differential transmission spectrum. Our approach combines broad spectral coverage with high sensitivity, due to high-frequency modulation and detection. We demonstrate its performances by measuring two-dimensional differential transmission maps of a carbon nanotubes sample, simultaneously acquiring the signal over the entire 950-1350 nm range with 2.7·10-6 rms noise over 1.5 s integration time.