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High-peak-power optically pumped passively mode-locked semiconductor laser with minimal components
Optics Letters
|August 15, 2023
Summary
This study presents a novel, compact optically pumped semiconductor laser achieving sub-500 femtosecond (fs) pulses. It demonstrates stable fundamental and harmonic mode locking (HML) with high peak power up to 0.95 kW.
Area of Science:
- Optics and Photonics
- Semiconductor Lasers
- Ultrafast Lasers
Background:
- Mode-locked semiconductor lasers are crucial for applications requiring ultrashort pulses.
- Developing compact, high-peak-power ultrafast laser sources remains a significant challenge.
- Optically pumped semiconductor lasers offer a versatile platform for generating ultrashort pulses.
Purpose of the Study:
- To develop a high-peak-power, sub-500 femtosecond (fs) mode-locked optically pumped semiconductor laser.
- To investigate the laser's operational modes, including fundamental and harmonic mode locking (HML).
- To characterize the pulse width and peak power performance across different HML orders.
Main Methods:
- A simplified laser cavity design utilizing only three components: a semiconductor gain chip, a semiconductor saturable absorber, and a focusing lens.
- Optical pumping with a pump power threshold identified for stable fundamental mode locking.
- Systematic variation of pump power to induce and study stable harmonic mode locking (HML) from 2nd to 8th order.
Main Results:
- Stable fundamental mode locking achieved near a pump power of 3.9 W.
- Naturally transitioned to stable harmonic mode locking (HML) with orders from 2nd to 8th as pump power increased from 4.0 W to 5.0 W.
- For HML orders below 8th, peak power was ~0.36 kW and pulse width ~550 fs.
- At 8th-order HML (pump power > 5.0 W), minimum pulse width reached 480 fs and maximum peak power reached 0.95 kW, attributed to high-order transverse modes.
Conclusions:
- An innovative and compact three-component optically pumped semiconductor laser capable of producing high-peak-power, sub-500 fs pulses has been successfully developed.
- The laser exhibits stable fundamental and tunable harmonic mode locking (HML) by adjusting pump power.
- The 8th-order HML operation demonstrates significant potential for applications requiring intense ultrashort optical pulses.
