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Fluoride semiconductor saturable-absorber mirror for ultrashort pulse generation
Optics Letters
|November 23, 2007
Summary
Researchers developed the first ultrabroadband AlGaAs/CaF(2) semiconductor saturable-absorber mirror (SESAM). This device enables self-starting sub-10-femtosecond pulses in Ti:sapphire lasers.
Area of Science:
- Optics and Photonics
- Materials Science
- Laser Physics
Background:
- Semiconductor saturable-absorber mirrors (SESAMs) are crucial for ultrashort pulse generation.
- Existing SESAMs often have limited bandwidth, restricting their use with broadband lasers like Ti:sapphire.
- Monolithic growth of dissimilar materials presents fabrication challenges.
Purpose of the Study:
- To demonstrate the first ultrabroadband monolithically grown AlGaAs/CaF(2) SESAM.
- To achieve SESAM performance covering the entire gain spectrum of a Ti:sapphire laser.
- To enable self-starting ultrashort pulse generation with sub-10-femtosecond durations.
Main Methods:
- Monolithic growth of AlGaAs/CaF(2) heterostructures.
- Fabrication of a six-layer SESAM device.
- Characterization of optical properties including reflectivity bandwidth, modulation depth, and recovery times.
- Integration of the SESAM into a Ti:sapphire laser cavity.
Main Results:
- Demonstrated an ultrabroadband SESAM with >300 nm high-reflectivity bandwidth.
- Achieved a modulation depth of 2.2% and fast recovery time (<150 fs).
- Successfully generated self-starting sub-10-femtosecond pulses from a Ti:sapphire laser.
Conclusions:
- The novel AlGaAs/CaF(2) SESAM is the first of its kind for ultrabroadband operation.
- The device's performance is suitable for mode-locking broadband lasers.
- This SESAM technology facilitates the generation of extremely short optical pulses.
