Low-threshold femtosecond Nd:glass laser

Using a 150-mW single-transverse-mode laser diode at 802 nm for pumping an Nd:phosphate laser, we achieved efficient cw operation (40% slope efficiency) with pump threshold as low as 12 mW at optimum coupling, and a maximum output power of 53 mW. Under passive modelocking operation, we obtained nearly Fourier-limited 270-fs pulses in a prismless dispersion-compensated cavity and 173-fs pulses with a single-prism setup. This compact laser is especially interesting for applications requiring low power levels, such as seeding amplifiers and for biodiagnostics.