Core-resonance capillary-fiber whispering-gallery-mode laser

Abstract

We describe the observation of laser emission at wavelengths corresponding to whispering-gallery modes from a highly refractive dye-doped solvent flowing in a normally illuminated silica capillary fiber. The cylindrical whispering-gallery-mode laser described here differs from the well-known spherical droplet laser in that it has an internal refractive index discontinuity. Boundary-value computations are presented that reveal that the feedback responsible for the observed lasing modes is associated with total internal reflection at the liquidsilica interface. No laser peaks are observed when the refractive index of the solvent is less than that of the silica.

Bioinspired optofluidic FRET lasers via DNA scaffolds

“…fluorescence resonance energy transfer | optofluidics | ring resonators 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)(2)(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.…”

Optofluidic Ring Resonator Dye Microlasers

“…It should be emphasized that the wall thickness is crucial in low-threshold lasers, as the thick wall prevents the low radial order WGMs, which have the highest Q-factors, from being exposed to the core. No lasing is observed when a thick-walled capillary is filled with ethanol dye solution 8,15 . When n core is increased to 1.445 ( Fig.…”

“…Optical feedback in these microfluidic dye lasers is provided by Fabry-Pérot-type cavities [3][4][5]7 or embedded distributed feedback gratings 2,6 . Ring resonator dye lasers based on evanescent wave coupled gain have also been demonstrated [8][9][10][11][12] . In a ring resonator, the whispering gallery modes (WGMs) form because of the light total internal reflection along the curved interface between the high and low refractive index (RI) media 13 .…”

“…For example, high RI liquid is needed in DFB lasers and liquid waveguide lasers 6,7,14 . On the one hand, high index core is also necessary to achieve lasing in a capillary with a thick wall (tens to hundreds of micrometers in thickness), and no lasing is observed when the core RI is lower than that of the wall 8,15 . On the other hand, for the ring resonator lasers that rely on the evanescent gain in the surrounding medium, the low RI liquid is imperative, as no WGM would exist when the RI of the liquid is larger than that of the ring resonator 10,12 .…”

Tunable single mode lasing from an on-chip optofluidic ring resonator laser

“…1,2 As compared to other types of optical cavities explored for optofluidic lasers, such as Fabry-Perot resonators [3][4][5] and distributed-feedback ͑DFB͒ gratings, [6][7][8] optofluidic ring resonators ͑OFRRs͒ that support the circulating resonant waveguide mode or the whispering gallery mode take advantage of compact size and relatively high Q-factors, both of which are a key to achieving large scale integration and low lasing thresholds. The OFRR lasers have previously been implemented in the form of discrete ring cavities, 9 microdroplets, 10 microknots, 11 microcylinders, [12][13][14] and microcapillaries. 15,16 Very recently, on-chip polydimethylsiloxane ͑PDMS͒ based OFRRs were also demonstrated.…”