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HL: Fachverband Halbleiterphysik

HL 18: Lasers and LEDs I

HL 18.3: Talk

Monday, March 11, 2013, 15:30–15:45, H16

Passively mode-locked red AlGaInP-VECSEL emitting < 50 ps pulses — •Roman Bek, Hermann Kahle, Thomas Schwarzbäck, Michael Jetter, and Peter Michler — Institut für Halbleiteroptik und Funktionelle Grenzflächen and Research Center SCoPE, Universität Stuttgart, Allmandring 3, 70569 Stuttgart, Germany

Since the first introduction of a semiconductor saturable absorber mirror (SESAM) into a vertical external cavity surface-emitting laser (VECSEL) in 2000, there has been substantial progress regarding pulse duration, repetition rate and output power. Despite the numerous advantageous properties of these mode-locked VECSELs like the possibility of bandgap engineering and near-diffraction-limited beam quality, most research has been limited to the infrared spectral range from 830 nm to 1.5 µm. We present SESAM mode locking of a VECSEL producing pulses with a FWHM duration below 50 ps and a repetition rate of 810 MHz at around 665 nm. The metal-organic vapor-phase epitaxy fabricated structures include a Bragg mirror consisting of 55 λ/4 pairs of AlGaAs/AlAs on a GaAs substrate. The following active region of the VECSEL has a resonant periodic gain structure containing 20 GaInP quantum wells. Two of the same quantum wells serve as absorber layers in the SESAM using fast surface recombination. The SESAM structure has a resonant design with an additional SiO₂ coating for low saturation fluence and a flat group delay dispersion. We use a V-shaped cavity with an overall length of 185 mm to strongly focus onto the SESAM where the folding mirror is used for outcoupling.