Low-threshold random lasers enhanced by titanium nitride nanoparticles suspended randomly in gain solutions

Area of Science:

• Photonics and Nanomaterials Science

Background:

• Random lasers offer unique light amplification properties.
• Enhancing pump efficiency and light-matter interaction is crucial for lowering lasing thresholds.

Purpose of the Study:

• To investigate the use of titanium nitride (TiN) nanoparticles to reduce the threshold of random lasers.
• To explore the underlying mechanisms of threshold reduction.
• To optimize TiN nanoparticle concentration and explore alternative gain media.

Main Methods:

• Suspension of TiN nanoparticles in gain solutions (DCM dye).
• Comparison with titanium dioxide (TiO2) nanoparticles.
• Analysis of localized surface plasmon resonance and multiple scattering effects.
• Investigation of TiN nanoparticle number density.
• Substitution of ethanol with nematic liquid crystals (NLC) as the gain medium.

Main Results:

• TiN nanoparticles significantly lower the random laser threshold compared to TiO2 nanoparticles.
• Localized surface plasmon resonance of TiN NPs enhances pump and fluorescence amplification.
• Multiple scattering by TiN NPs increases light dwelling time, promoting amplification.
• An optimal TiN NP concentration of approximately 1.468 × 10^12 ml^-1 was identified.
• Using nematic liquid crystals further reduced the threshold to 5.11 µJ/pulse, 7.7 times lower than DCM dye with TiN NPs.

Conclusions:

• TiN nanoparticles provide a viable strategy for creating low-threshold random lasers.
• The enhanced performance is attributed to plasmonic and scattering effects of TiN NPs.
• Nematic liquid crystals offer a promising host for achieving ultra-low threshold random lasers cost-effectively.