Subpicosecond pulse generation from a 1.56 μm mode-locked VECSEL.

Area of Science:

• Optics and Photonics
• Semiconductor Lasers
• Ultrafast Optics

Background:

• Vertical-external-cavity surface-emitting lasers (VECSELs) are promising for high-power laser applications.
• Achieving ultrashort pulse durations is crucial for various scientific and technological fields.

Purpose of the Study:

• To generate near-transform-limited subpicosecond pulses from an optically pumped InP-based VECSEL.
• To investigate the effect of semiconductor saturable absorber mirror (SESAM) properties on pulse duration.

Main Methods:

• Utilized an InP-based VECSEL passively mode-locked at a 2 GHz repetition rate.
• Employed a fast InGaAsNSb/GaAs semiconductor saturable absorber mirror (SESAM).
• Adjusted SESAM microcavity resonance via selective etching of phase layers to control modulation depth and intracavity group delay dispersion.

Main Results:

• Generated near-transform-limited subpicosecond pulses at 1.56 μm.
• Reduced mode-locked pulse duration from several picoseconds to less than 1 picosecond by detuning the resonant SESAM.
• Demonstrated control over pulse duration by tuning SESAM properties.

Conclusions:

• Optically pumped InP-based VECSELs can achieve subpicosecond pulse generation.
• SESAM microcavity resonance tuning is an effective method for controlling ultrashort pulse durations.
• This work advances the development of VECSELs for ultrafast applications.