Opto-fluidic ring resonator lasers based on highly efficient resonant energy transfer

Abstract

We demonstrate an opto-fluidic ring resonator dye laser using highly efficient energy transfer. The active lasing material consists of a donor and acceptor mixture and flows in a fused silica capillary whose circular cross section forms a ring resonator and supports the whispering gallery modes (WGMs) of high Q-factors (>107). The excited states are created in the donor and transferred to the acceptor through the fluorescence resonant energy transfer (FRET), whose emission is coupled into the WGM. Due to the high energy transfer efficiency and high Q-factors, the acceptor exhibits a lasing threshold as low as 0.3 muJ/mm2. We further analyze the energy transfer mechanisms and find that non-radiative Förster transfer is the dominant effect to support the acceptor lasing. FRET lasers using cascade energy transfer and using quantum dots (QDs) as the donor are also presented. Our study will not only lead to development of novel microfluidic lasers with low lasing thresholds and excitation/emission flexibility, but also open an avenue for future laser intra-cavity bio/chemical sensing.

Bioinspired optofluidic FRET lasers via DNA scaffolds

“…The details of OFRR fabrication have been previously reported (9,15). Briefly, a fused silica capillary preform (Polymicro Technologies TSP700850) is first etched with diluted hydrofluoric acid and then rapidly stretched under CO 2 laser irradiation.…”

“…The energy transfer significantly extends the laser emission wavelength range without the need to change the pump wavelength. Moreover, dye lasers based on energy transfer have a much higher pump efficiency and lower lasing threshold than the corresponding single dye lasers due to the low donor absorption loss at the acceptor lasing wavelength (14,15).…”

“…Generally, there are two transfer mechanisms between the donor and the acceptor in an optical cavity: nonradiative FRET (14)(15)(16)(17), in which the transfer is mediated by short-ranged resonant dipole-dipole interaction, and cavity-assisted radiative transfer (18)(19)(20), in which the emission from the donor is first coupled into the cavity, which stores photons for an extended amount of time before they are reabsorbed by the acceptor. The FRET efficiency between a donor and acceptor pair is R 0 6 ∕ðR 0 6 þ r 6 Þ, where R 0 and r are the Förster distance and the donor-acceptor distance, respectively.…”

“…The cavity-assisted transfer efficiency is determined by the fraction of donor emission into cavity modes and the probability of acceptor reabsorption (18,19) (see SI Text for detailed analysis). Unfortunately, to date only a handful of energy transfer based optofluidic lasers have been demonstrated (15,17). In those lasers, the donor and the acceptor are distributed homogeneously in solution.…”

Multicolor lasing prints

“…24,25 In particular, multicolor lasers enabled by energy transfer, especially nonradiative F€ orster resonance energy transfer (FRET), 26 are very interesting cases because they offer extended lasing wavelengths, high pumping efficiency, and low lasing threshold. [27][28][29] In this work, high Q-factor, dual-color lasing from arrays of hemispherical microcavities fabricated by inkjet method is demonstrated.…”