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 sufficient 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 1122 nm to 1178 nm 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 amplified by a subsequent tapered amplifier (TPA) in a master oscillator power amplifier (MOPA) configuration. Here, the TPA is in cw-operation. The amplified 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 47 mm × 76 mm which also supports a polarization maintaining fiber output. The concept has been realized at emission wavelengths of 561 nm and 589 nm, respectively. At 561 nm 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 589 nm have similar temporal characteristics but slightly lower optical output power of more than 1W pulse peak power.