Ultralow-threshold green fluorescent protein laser based on high Q microbubble resonators

Area of Science:

• Biophotonics and Medical Lasers
• Fluorescent Protein Applications
• Optical Resonator Technology

Background:

• Biological lasers are crucial for medical applications, particularly ultrasensitive detection.
• Low-threshold lasers minimize damage to biological gain media during pumping.
• Green fluorescent protein (GFP) is a key bioluminescent material for laser development.

Purpose of the Study:

• To fabricate a miniature green fluorescent protein (GFP) laser with exceptionally low threshold energy.
• To achieve a high Q value in a biological laser for enhanced performance.
• To assess the stability and sensitivity of the developed GFP laser for biological detection.

Main Methods:

• Coupling a low-concentration green fluorescent protein (GFP) solution with a high Q whispering gallery mode microbubble resonator.
• Characterizing the laser threshold energy and Q value of the fabricated device.
• Evaluating the long-term operational stability and sensitivity to GFP concentration.

Main Results:

• A miniature GFP laser was successfully fabricated with a record-low threshold energy of 380 fJ.
• The laser achieved a high Q value of 5.3 × 10⁷, significantly exceeding previous GFP lasers.
• The device demonstrated long-term stability, functioning for nearly a month at 3-4°C, and high sensitivity for GFP detection.

Conclusions:

• The developed miniature GFP laser offers unprecedented low threshold and high Q values.
• This technology enables ultrasensitive detection of GFP concentration, valuable for GFP tracer applications.
• The biological laser shows significant promise for advanced medical diagnostics and biological sensing.