Bio-inspired random lasers enabled by poplar catkin microstructures

Area of Science:

• Photonics and Laser Technology
• Materials Science
• Biomaterials Engineering

Background:

• Conventional lasers often suffer from speckle noise, hindering high-resolution imaging.
• Developing cost-effective and environmentally friendly laser platforms is crucial for advanced optical applications.
• Natural biomaterials offer potential as sustainable components in photonic devices.

Purpose of the Study:

• To investigate the feasibility of using poplar catkin fibers (PCFs) as a scattering matrix for random lasers (RLs).
• To optimize PCF concentration for enhanced lasing performance and reduced speckle.
• To demonstrate the application of the developed RL for speckle-free imaging.

Main Methods:

• Fabrication of solution-processed gain media incorporating Rhodamine 6G and varying concentrations of PCFs (1.5–5.5 mg/mL).
• Characterization of lasing thresholds, emission spectra, and output stability under optical pumping.
• Analysis of spatial coherence and speckle contrast, followed by speckle-free imaging tests using a USAF 1951 target and a dragonfly wing.

Main Results:

• Optimal lasing threshold achieved at 4.5 mg/mL PCF concentration (8.21 µJ/pulse) due to hierarchical fibrous network scattering.
• Significant spectral narrowing (14.8 nm to 0.8 nm) and redshift observed, indicating enhanced scattering strength.
• Speckle contrast reduced to 0.0755, significantly lower than conventional lasers, enabling high-fidelity speckle-free imaging.

Conclusions:

• Poplar catkin fibers serve as an effective, biodegradable scattering matrix for random lasers.
• The developed PCF-based random laser offers a low-cost, green platform for speckle-free imaging.
• Potential applications include bioimaging, environmental sensing, and flexible photonics.