Tunability of optofluidic distributed feedback dye lasers.

Area of Science:

• Optofluidics
• Laser Physics
• Materials Science

Background:

• Distributed feedback (DFB) lasers are crucial for tunable coherent light sources.
• Optofluidic integration offers miniaturization and enhanced functionality for laser systems.

Purpose of the Study:

• To investigate and demonstrate the tunability of optofluidic DFB dye lasers.
• To explore the use of nano-structured polymer films with nanofluidic channels for laser resonators.
• To assess the performance metrics including threshold and tuning range.

Main Methods:

• Fabrication of a third-order Bragg grating DFB laser resonator using a nano-structured polymer film with nanofluidic channels.
• Operation via capillary filling with laser dye and optical pumping using a frequency-doubled Nd:YAG laser.
• Wavelength tuning by altering the grating period and dye solution refractive index.

Main Results:

• Observed low threshold fluences down to ~7 microJ/mm2.
• Achieved a significant 45 nm wavelength tunability using a single laser dye.
• Demonstrated low out-of-plane scattering losses due to the low reflection order of the DFB resonator.
• Confirmed a large free spectral range (FSR) facilitating broad tuning.

Conclusions:

• Optofluidic DFB dye lasers offer a highly tunable and efficient coherent light source.
• The demonstrated tunability and low thresholds make these lasers suitable for lab-on-a-chip microsystems.
• Potential applications include novel sensor concepts requiring visible coherent light.