Whispering gallery mode biosensor operated in the stimulated emission regime

François, Alexandre; Himmelhaus, Michael

doi:10.1063/1.3059573

Cited by 73 publications

(72 citation statements)

References 23 publications

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“…5c) 86 . Another study found that protein adsorption kinetics can be measured with improved signal-to-noise ratio when using whispering gallery mode resonators based on fluorescent polymer microspheres and operating these above the laser threshold 87 . For biosensing, lasers based on biologically produced materials, such as green fluorescent protein 4,51 or fluorescent vitamins 88 are uniquely suited to generate laser light within living organisms (Fig.…”

Section: Applicationsmentioning

confidence: 99%

Advances in small lasers

2014

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In recent years there have been significant advances in the size and characteristics of small lasers, i.e. lasers with dimensions or modes sizes close to or smaller than the wavelength of emitted light. This work has primarily been led by innovative use of new materials and cavity designs. This article reviews some of the latest developments, particularly in metallic and plasmonic lasers, improvements in small dielectric lasers, and the emerging area of small bio-compatible/bioderived lasers. We examine the different approaches employed in small lasers to reduce size and how they lead to significant differences , particularly between metal and dielectric cavity lasers. We present potential applications for the various forms of small lasers and indicate where further developments are required.

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Section: Applicationsmentioning

confidence: 99%

Advances in small lasers

2014

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“…Large resonators, ranging from 50 to 300μm in diameter, typically exhibit a Qfactor up to several millions [1,3,16], whereas smaller resonators (below 20μm in diameter) reported in literature have been limited to a Q-factor of around 10 3 in liquids [8,13]. One approach for improving the Q-factor of small resonators is the use of active resonators [6,7,17] which contain a gain medium (unlike passive resonators [1][2][3]) and can induce lasing of the WGMs. Using this strategy, it has been found that the Q-factor of the lasing modes can be increased by up to a factor 5, compared to the non-lasing modes, as the signal-to-noise ratio is significantly increased [17].…”

Section: Introductionmentioning

confidence: 99%

“…One approach for improving the Q-factor of small resonators is the use of active resonators [6,7,17] which contain a gain medium (unlike passive resonators [1][2][3]) and can induce lasing of the WGMs. Using this strategy, it has been found that the Q-factor of the lasing modes can be increased by up to a factor 5, compared to the non-lasing modes, as the signal-to-noise ratio is significantly increased [17].…”

Section: Introductionmentioning

confidence: 99%

Enhancing the radiation efficiency of dye doped whispering gallery mode microresonators

François¹,

Rowland²,

Afshar³

et al. 2013

Opt. Express

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“…Like other kinds of optical resonators, also WGM microresonators can be operated above the lasing threshold, e.g., by pumping the gain medium with a short pulse laser [2]. Lasing can only be achieved when the amplification of a certain mode exceeds the losses per roundtrip, which is feasible only with sufficiently high quality (Q-) factors of the resonator modes.…”

Section: The Lasing Regimementioning

confidence: 99%

“…ferent polarization and different quantum numbers q and n. The sharp peaks correspond to WGMs with q = 1, some broader features difficult to resolve to WGMs with higher q. The spacing between peaks of same polarization, the so-called free spectral range (FSR), can be used for precise calculation of the sphere size, according to R = λ 2 / (2π n MR δλ), with δλ = λ n -λ n + 1 = FSR, and λ 2 = λ n λ n + 1 (2) Any variances in the absolute peak position of any of the modes can be exploited for the sensing of changes in the resonator condition or that of its ambient. Since excitation and readout of WGM microresonators can be achieved optically, e.g., by application of a long distance optical micro-objective (Fig.…”

Section: Berlin Germanymentioning

confidence: 99%

Microsensors on the Fly

Himmelhaus¹

2016

Optik & Photonik

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Optically driven microresonators freely floating in liquids, embedded into transparent solid media, or even taken up by life cells, can be exploited as optical microsensors, which yield precise information on the immediate local condition of their respective environment. Besides plain physical information, such as on local refractive indices, mechanical stress, and mixture ratios in composite materials, the sensors may be applied as chemical and even bio-sensors for the specific targeting of biochemical binding reactions if accordingly functionalized. Sensitivity can be further improved by driving the sensors above the lasing threshold, thereby increasing signal intensity and optical resolution at the same time. In this article, we introduce the optical principles, present useful implementations, and illustrate feasibility of this still novel approach to optical sensing by a number of diverse examples.With the advent of the laser diode, microresonators capable of confining light to microscopic volumes have entered everyday's life with applications as laser pointers, light sources in CD, DVD and Blu-ray disk drives, and do-it-yourself metrology tools, to name just the most common examples. Intrinsically shaped into their gain medium, these semiconductor devices can achieve extremely small sizes in the micrometer regime, however, since they are electrically powered, they require a fixed connection to the macroscopic world in the form of some electrical driver, which still renders the entire device macroscopic.Here, we report about optically driven microresonators that overcome the need for fixation to a macroscopic power supply and thus turn into microsensors of 3D quantum system characterized by quantum numbers q, n, m for radial, azimuthal, and polar quantization and polarizations TE, TM (transverse electric / transverse magnetic modes, respectively). Fig. 1 (a) Illustration of a whispering gallery mode with quantum numbers q = 3 (three radial maxima), n = 44 (no. of wavelengths along circumference), and m = n (1 polar maximum); (b) Cross section in radial direction showing the field distribution of the WGM of (a); please note the exponential decay outside of the microresonator, which is a peculiarity of WGM resonators; (c) Fluorescence emission spectra of 10 µm coumarin 6G doped polystyrene microbeads as recorded with a set up as sketched in Fig. 2c; the spectrum plotted in blue origi nates from a spherical bead and exhibits several WGMs with q = 1 and several quantum numbers n (distinguished by a different number of wavelengths fitting into the circumference of the bead). For each quantum number n, there is a pair of modes with differing polariza tion (TE, TM) as indicated in the spectrum. The spectrum plotted in red stems from a particle stained with the same fluorophore, but with an odd shape, so that WGMs are not supported. By subtraction of the two spectra, the non resonant fluorescence background can be removed and the pure WGM spectrum is obtained (spectrum in green, Data of (c) taken from [6]).

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Whispering gallery mode biosensor operated in the stimulated emission regime

Abstract: . Whispering gallery mode biosensor operated in the stimulated emission regime, Applied Physics Letters, 2009; 94(3):031101-1.

Cited by 73 publications

References 23 publications

Advances in small lasers

Advances in small lasers

Enhancing the radiation efficiency of dye doped whispering gallery mode microresonators

Microsensors on the Fly

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