Fiber-format CARS spectroscopy by spectral compression of femtosecond pulses from a single laser oscillator.
We demonstrate an approach to coherent anti-Stokes Raman scattering (CARS) spectroscopy/microscopy based on spectral compression of femtosecond pulses emitted by a compact Er-fiber oscillator. Spectral compression is achieved by group-velocity mismatched second-harmonic generation in periodically poled nonlinear crystals, and it allows efficient synthesis of synchronized narrow-bandwidth (less than 10 cm(-1)) pump and Stokes pulses with the frequency difference continuously tunable up to approximately 3000 cm(-1). CARS signal enhancement by up to 3 orders of magnitude is obtained by interferometric superposition with a phase-coherent local oscillator field, also synthesized by spectral compression.
Marangoni
Marco
M
Dipartimento di Fisica, Politecnico di Milano, ULTRAS-CNR-INFM, IFN-CNR Piazza Leonardo da Vinci 32, 20133 Milano, Italy. marco.marangoni@polimi.it
Gambetta
Alessio
A
Manzoni
Cristian
C
Kumar
Vikas
V
Ramponi
Roberta
R
Cerullo
Giulio
G
D007834:Lasers; D008853:Microscopy; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013997:Time Factors