Dual coherent anti-Stokes Raman scattering microscopy across the vibrational spectrum enabled by single pump optically synchronised oscillators and spectral focusing

Abstract

Coherent anti-Stokes Raman scattering microscopy probing two independently selectable vibrational frequencies across the vibrational spectrum is demonstrated. A one-box femtosecond laser source provides three synchronised 100–200 fs pulses of 77 MHz repetition rate, one at a fixed wavelength of 1025 nm from an Yb oscillator and two independently tuneable ones, over 680–960 nm and 960–1300 nm, respectively, from two optically synchronised parametric oscillators. Combined with spectral focusing, the source allows addressing the fingerprint, cell silent and C–H stretch vibrational regions simultaneously, avoiding the motion artefacts seen in sequential imaging. We demonstrate the microscopy method on water/heavy water/oil emulsions, plastic beads and deuterated lipids inside cells.