Multiphoton microscopy at a microwatt level via gain-managed nonlinear amplification and pulse-picking

We introduce a compact, all-fiber laser system with a gain-managed nonlinear (GMN) amplified Yb:fiber oscillator and an integrated pulse-picker. The system delivers 39 fs pulses with peak powers of 0.83 MW and adjustable pulse repetition rates (0.3-15 MHz), enabling multiphoton imaging at remarkably low excitation powers (as low as 66 µW). Its design simplifies integration and enhances experimental flexibility. Compatible with two- and three-photon excitation, but also second harmonic generation microscopy, this versatile system offers precise control of imaging parameters, making it an effective tool for advancing multiphoton microscopy and other imaging techniques across various experimental environments.