Three-photon microscopy with a monolithic all-fiber format laser emitting at 1650 nm
Résumé
One optimal window for biological imaging lies around 1675 ± 20 nm wavelength, a result of the decreased effects of both tissue scattering and water absorption. Furthermore, in nonlinear microscopy the signal-to-background ratio, which limits the maximum penetration depth, is dramatically increased with increasing photon order. As a consequence, three-photon microscopy with an excitation wavelength of approximately 1675 nm was recently proposed as a promising approach for deep microscopic imaging of live tissues. Wide adoption of this technique will rely on cost-effective and environmentally insensitive lasers operating at this exotic wavelength. In this communication we report on a monolithically integrated high repetition rate all-fiber femtosecond laser operating in the spectral range from 1650 to 1700 nm. The laser is based on custom-designed large mode area erbium-doped fiber operated in the nonlinear regime. We explore its potential for biological microscopy by imaging live embryonic tissue.