Multi Watt-Level Picosecond Micro-Laser Sources in the Yellow-Green Spectral Range

Pulsed diode laser sources in the yellow-green spectral range are highly demanded for applications like label-free imaging or stimulated emission depletion (STED) microscopy. However, direct emitting diode lasers are not yet providing su ffi cient emission characteristics and lifetime behavior. In this work pulsed laser sources that make use of reliable near infrared diode lasers in the wavelength range from 1122nm to 1178nm and single-pass second harmonic generation are presented. A ridge waveguide laser with integrated distributed Bragg-reflector (DBR-RWL) is operated in gain-switched pulsed operation. The laser pulses are further ampli fi ed by a subsequent tapered ampli fi er (TPA) in a master oscillator power amplifier (MOPA) con fi guration. Here, the TPA is in cw-operation. The ampli fi ed laser pulses are then coupled into a periodically poled lithium niobate ridge waveguide crystal. The whole setup fits into a butterfly housing with a footprint of only 47mm x 76mm which also supports a polarization maintaining fiber output. The concept has been realized at emission wavelengths of 561nm and 589 nm, respectively. At 561nm laser pulses with a full width at half maximum (FWHM) of 100 ps and peak power of more than 2 : 5W could be demonstrated, which is a nearly tenfold increase compared to previous work without TPA. The pulses at 589nm have similar temporal characteristics but slightly lower optical output power of more than 1W pulse peak power.