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

TL;DR

This paper reports a highly sensitive, ultralow-threshold green fluorescent protein laser using a high Q microbubble resonator, achieving record low excitation energy and long-term stability for biological detection applications.

Contribution

It introduces a novel GFP laser with ultralow threshold and high Q factor, demonstrating long-term stability and potential for sensitive biological detection.

Findings

Lasing threshold of 500 nJ/mm^2 achieved

Excitation energy reduced to 380 fJ, lowest known for GFP lasers

Laser remains stable for at least 23 days

Abstract

Biological lasers have attracted vast attention because of their potential medical application prospects, especially the low threshold biological laser, which can be used for ultrasensitive biological detection while ensuring that its luminous gain medium is not damaged by the high-energy pump light. By coupling the low concentration green fluorescent protein (GFP) solution with a high Q whispering gallery mode microbubble resonator, we managed to fabricate a miniature GFP laser with ultralow lasing threshold of 500 nJ/mm^2. The energy used to excite the GFP can be reduced to 380 fJ, two orders of magnitude lower than that of the lowest excitation energy GFP laser known. The Q value of the optical cavity in this biological laser is 5.3 x 10^7, the highest among GFP lasers at present. We further confirmed the long-term stability of the working characteristics of GFP laser for the first time and found that its optical characteristics can be maintained for at least 23 days. Finally, we measured the effects of different concentrations of fluorescent protein on the laser threshold. The data show that this biological laser can be used for a highly sensitive detection of GFP concentration.