Fiber based optical parametric oscillator for high fidelity coherent anti-stokes Raman (CARS) microscopy

An optical parametric oscillator based on four-wave mixing (FOPO) is presented with the ability to tune in and switch between closely spaced molecular resonances of different specimen. The FOPO generates high repetition rate (4MHz) powerful temporally synchronized and spectrally separated nearly-transform-limited picosecond pulses (<30ps), hence, the source is well suited for an ultra-compact source for high fidelity CARS applications. High resolution CARS microscopy images probing CH2 and CH3 resonances demonstrate the potential.