The Study on Lasing Threshold Properties of Rhodamine B in Glycerol Aqueous Solution

Abstract

An optical fiber is integrated in a polydimethylsiloxane substrate microfluidic channel. The laser gain medium consists of glycerol aqueous solution doped with rhodamine B (RhB) molecules, which has a lower refractive index (RI) than that of the optical fiber. The circular cross section of the optical fiber forms an optofluidic ring resonator and hosts highquality (Q) whispering gallery modes (WGMs). Optically pumped along the fiber axis, lasing threshold properties of the RhB glycerol aqueous solution have been investigated. With the increase of both RhB dye concentration and the RI of the glycerol aqueous solution, the recorded lasing threshold decreases at first and then increases. Therefore, there is a best dye concentration as well as a best RI of the dye solution that corresponds to the lowest lasing threshold. Additionally, lasing threshold for the mixed solution of ethanol and ethylene glycol doped with RhB molecules is also demonstrated, which is much higher than that of the glycerol aqueous solution for the same dye concentration and the same RI of the dye solution. Based on evanescent wave pumped and gain coupled WGM lasing theory, we compute the lasing threshold varied with the dye concentration and the RI of the dye solution. The simulation results agree well with the experimental data.

Fluorescence spectroscopy based characterisation method for aggregation behaviour of rhodamine B (RhB) in water, ethanol, and propanol

“…alternate single and double bonds [12]. Rhodamine B is usually selected as a gain medium for OFRR laser in the wavelength range of 578-610 nm and it is generally dissolved in solvents such as pure water, ethanol, ethylene glycol, and glycerol [13]. The lasing threshold, the tuning range of the emitted lasing wavelength, and the fluorescence quantum yield of the dye directly depend on the solvent of the dye [14,15].…”

Large dynamic range dual-mode pH sensors via dye-doped ionic liquid fiber optofluidic lasers

“…We consider that the remarkable performance of BmimPF 6 as the solvent of RhB is mainly attributed to its inherent viscosity ( η ) and its good thermal stability (low thermal conductivity ( κ )). As summarized in Table 1, on one hand, large viscosity will cause a high dye fluorescence lifetime ( τ ) and QY, 25 i.e. , higher QY (0.889) and τ (4.28 ns) in BmimPF 6 are achieved with respect to a lower QY and τ of 0.741 and 3.77 ns in GAS, leading to a lower lasing threshold of RhB-doped BmimPF 6 than that of the RhB-doped GAS, as shown in Fig.…”

“…The details of the experimental setup have been reported elsewhere. 25 Briefly, an optical fiber (refractive index (RI) = n 1 = 1.458) with a diameter of 200 μm is integrated into the PDMS (RI = 1.405) microchannel. The RhB-doped BmimPF 6 solution ( n 2 = 1.411) passes through the microchannel and functions as the gain cladding medium of the fiber.…”

Versatile Optofluidic Solid-Core/Liquid-Cladding Waveguide Based on Evanescent Wave Excitation

“…The chip shown in Figure A is fabricated using the standard PDMS soft lithography. The details of the fabrication process are described in ref . The size of the chip is 20 mm × 10 mm × 2 mm ( l × w × h ), and the dimension of the microfluidic channel is 15 mm × 400 μm × 400 μm.…”

“…The chip shown in Figure 1A is fabricated using the standard PDMS soft lithography. The details of the fabrication process are described in ref 24.…”