Bioinspired optofluidic FRET lasers via DNA scaffolds

Abstract

Optofluidic dye lasers hold great promise for adaptive photonic devices, compact and wavelength-tunable light sources, and micro total analysis systems. To date, however, nearly all those lasers are directly excited by tuning the pump laser into the gain medium absorption band. Here we demonstrate bioinspired optofluidic dye lasers excited by FRET, in which the donor-acceptor distance, ratio, and spatial configuration can be precisely controlled by DNA scaffolds. The characteristics of the FRET lasers such as spectrum, threshold, and energy conversion efficiency are reported. Through DNA scaffolds, nearly 100% energy transfer can be maintained regardless of the donor and acceptor concentration. As a result, efficient FRET lasing is achieved at an unusually low acceptor concentration of micromolar, over 1,000 times lower than that in conventional optofluidic dye lasers. The lasing threshold is on the order of μJ∕mm 2 . Various DNA scaffold FRET lasers are demonstrated to illustrate vast possibilities in optofluidic laser designs. Our work opens a door to many researches and applications such as intracavity bio/chemical sensing, biocontrolled photonic devices, and biophysics. O ptofluidic lasers are an emerging technology that combines the advantages of compactness and easy liquid manipulation of microfluidics, and dynamic wavelength tunability and broad spectral coverage of dye lasers (1-3). Optical feedback in those optofluidic lasers has been achieved using high-Q ring resonators [e.g., microdroplets (4, 5), microspheres (6), microcylinders (7), microcapillaries (8, 9), and microfiber knots (10)], Fabry-Pérot cavities (11, 12), and distributed feedback gratings (3, 13). In nearly all those lasers, the gain medium is directly excited by tuning the pump laser into the dye absorption band, which requires that the pump laser wavelength match the particular dye absorption. An alternative excitation scheme is through energy transfer, in which dye mixtures, composed of the donor and the acceptor, are used. Donors are directly excited and subsequently transfer energy to acceptors for lasing. 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 (14-17), 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, r...

Brillouin cavity optomechanics with microfluidic devices

“…By controlling the power of the manufacturing laser in the process of pulling, we can control the device diameter along its length. This process has also previously been developed in Sun et al 17 Optical WGMs and acoustic WGMs are simultaneously well-confined in the regions of large diameter sandwiched between regions of narrow diameter (Fig. 1d,e), enabling a high-degree of modal overlap.…”

“…Our mFOM device (Fig. 1a,b) is fabricated from a lengthwise-drawn fusedsilica capillary 17 with its radius modulated as a function of length (see Methods). At its widest point, this glass device forms a whispering-gallery mode (WGM) microresonator 18 that resonantly enhances both light and sound (Fig.…”

Advances in small lasers

“…Using the small laser configurations discussed above, intracellular lasing could be achieved without an external resonator, which may enable novel nonlinear imaging schemes or dense wavelength multiplexing. Micro-lasers based on fluorescently labeled DNA as gain medium may find applications in optical DNA sequencing 89 .…”

Electro-tunable liquid crystal laser based on high-Q Fabry-Pérot microcavity

“…A laser device with tunable wavelength would be particularly attractive as the light source in a micro total analysis system (µTAS), also known as a lab-on-a-chip, for biochemical sensing, since various dyes are utilized to stain the biomolecular analyte in the optical sensing platforms [3][4][5][6]. Optofluidic lasers [7][8][9] have been intensively investigated for these applications, due to their superior lasing characteristics and long-range wavelength tunability that is obtained by exchanging the liquid gain medium in the fluidic channel.…”