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Low-Threshold and Long-Term Stable Soliton Fiber Laser Using PbSe/PbS Quantum Dot-Polystyrene Composite Saturable
Bin Yang1, Jingping Shao1, Chunxiao Liu1
1Advanced Photonic Technology Lab, College of Electronic and Optical Engineering & College of Flexible Electronics, Nanjing University of Posts and Telecommunications, Nanjing 210023, China.
Nanomaterials (Basel, Switzerland)
|March 13, 2026
Summary
We developed a stable PbSe/PbS quantum dot composite for ultrafast fiber lasers. This new saturable absorber demonstrates low-threshold mode locking and excellent durability.
Area of Science:
- Materials Science
- Photonics
- Quantum Dots
Background:
- Colloidal lead selenide (PbSe) quantum dots are explored as saturable absorbers for ultrafast fiber lasers.
- Their application is hindered by surface defects, chemical instability, and aggregation under optical pumping.
Purpose of the Study:
- To create a robust and stable saturable absorber using PbSe/PbS quantum dots in a polymer matrix.
- To enhance the passivation and oxidation resistance of PbSe quantum dots via PbS overcoating.
Main Methods:
- Fabrication of a freestanding PbSe/PbS quantum dot-polystyrene composite film.
- Characterization of the composite's optical properties, including saturation intensity and damage threshold.
- Integration into an erbium-doped fiber laser for mode-locking performance evaluation.
Main Results:
- The composite exhibited a saturation intensity of 5.76 kW·cm⁻², a modulation depth of 33%, and an optical damage threshold of 13.6 mJ·cm⁻².
- Achieved self-starting soliton mode locking at an ultralow pump threshold of 6 mW in an erbium-doped fiber laser.
- Generated 1.06 ps pulses with high spectral stability over an 8-month period, demonstrating durability.
Conclusions:
- The PbSe/PbS quantum dot-polystyrene composite serves as a high-performance saturable absorber.
- This material platform offers excellent environmental and operational durability for ultrafast fiber lasers.
- The developed composite is a promising solution for low-threshold, stable mode-locked fiber laser systems.
