Refractive-index measurement of absorbing condensed media

Leupacher, W.; Penzkofer, Alfons

doi:10.1364/ao.23.001554

Cited by 52 publications

(27 citation statements)

References 21 publications

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“…The refractive indices (relative to air) of the fused silica cell windows are n t = 1.4497 and n 3 = 1.4765 [10]. The refractive indices n 1 = 1.3214 and n 3 = 1.3420 (T=25°C) of the solvent methanol were measured with a Pellin-Broca prism apparatus [8] while the refractive indices of the dye solutions were determined with a reflection technique [9]. The unknown susceptibility values |x (3) | are extracted from (2) by comparing the measured energy conversions with calculations.…”

Section: Methodsmentioning

confidence: 99%

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Third-order nonlinear susceptibilities of dye solutions determined by third-harmonic generation

Leupacher

Penzkofer

1985

Appl. Phys. B

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Abstract. The third-order nonlinear susceptibilities x { xxxx ( -^ w i> w i> &>i) versus concentration are determined for rhodamine 6G, fuchsin, and methylene blue in methanol. Third-harmonic generation of a modelocked Nd-glass laser is applied. The real and imaginary part of the nonlinear susceptibility are measured. A resonance enhancement due to absorption bands is observed. Here we determine the dependence of third-order nonlinear susceptibilities xx 3 xxx ( -^3; co l9 co u co x ) on dye concentration for rhodamine 6G, fuchsin and methylene blue in methanol. The efficiency of conversion of picosecond light pulses of a mode-locked Ndglass laser to the third harmonic is measured. The nonlinear susceptibilities are deduced by comparison with calculations [7]. The absorption coefficients and refractive indices entering the calculations are separately measured [8,9]. The nonlinear susceptibilities comprise contributions from the solvent and the solute. The complex solute hyperpolarizabilities are determined and compared with the real solvent hyperpolarizability. The resonance enhancement is analyzed.

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Section: Methodsmentioning

confidence: 99%

“…The nonlinear susceptibilities are deduced by comparison with calculations [7]. The absorption coefficients and refractive indices entering the calculations are separately measured [8,9]. The nonlinear susceptibilities comprise contributions from the solvent and the solute.…”

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confidence: 99%

Third-order nonlinear susceptibilities of dye solutions determined by third-harmonic generation

Leupacher

Penzkofer

1985

Appl. Phys. B

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“…1, the refractive index of the medium for a concentration of 0.01 M of Rhodamine is shown. 8 It is clearly seen that the presence of the Rhodamine produces a significant imaginary part for the index, but also a strong variation of the real part in the region of the absorptive wavelength (anomalous dispersion). By introducing the corresponding values of the refractive index in our model, we have calculated the transmittance curves of the structure when the concentration of the dissolved Rhodamine is varied.…”

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confidence: 98%

Absorption as a selective mechanism in surface plasmon resonance fiber optic sensors

et al. 2006

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A new concept of surface plasmon resonance fiber optic sensor is presented. By tuning the plasmon resonance to a wavelength for which the outer medium is absorptive, a significant variation of the spectral transmittance of the device is produced as a function of the concentration of the analyte. With this mechanism, selectivity can be achieved without the need of any functionalization of the surfaces or the use of recognizing elements, which is a very interesting feature for any kind of chemical sensor or biosensor. Doubly deposited uniform-waist tapered fibers are well suited for the development of these new sensors. Multiple surface plasmon resonance, obtainable in those structures, can be used for the development of microspectrometers based on this principle. Surface plasmon resonance (SPR) has become a standard technique for a huge variety of chemical sensors or biosensors. 1 Plasmon excitation strongly depends on the refractive index of the surrounding medium, and, in that sense, all these sensors can be considered refractometers. To make the response of the devices selective to a specific analyte, recognizing elements must be added to the plasmon supporting structure. This requires a functionalization of the surfaces and a careful selection of the materials. The idea is to take advantage of the locality of the plasmon resonance and to ensure that the variation in the refractive index detected on the sensor is directly produced by the presence of the selected analyte.In general, the media considered in SPR spectroscopy are dielectric. Absorption has been taken into account as a possibility of sensitivity enhancement, but not clearly as the basis of a new recognizing technique.2-4 Chemical sensors and biosensors usually are based on attenuated total reflection configurations and therefore employ angular interrogation. For this reason, it is not easy to relate the absorptive spectrum of the outer medium, if it exists, with the obtained output signal. At the same time, the theoretical analyses become somewhat obscure, since spectral interrogation is not considered and the concept of matching of the wavelength associated to the plasmon resonance and one of the wavelengths of absorption for the outer medium is not clearly stated. Sometimes the phenomenon is misinterpreted, in our opinion, since the contributions of the imaginary and real parts of the refractive index of the medium are considered as clearly separable and responsible for different variations of the obtained reflectance curves.Spectral interrogation is a usual procedure with fiber optic sensors. When it is used, plasmons reveal themselves as well-defined dips in the spectral transmittance curves, and we can measure the wavelengths associated with the plasmon resonances and the displacements produced in the positions of these wavelengths by the changes in the refractive index of the outer medium. An evanescent field is commonly used to produce SPR fiber optic sensors, and, among the different techniques proposed, tapered optical fibers have proved t...

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“…The refractive index dispersion of the solvent hexafluoroisopropanol is included [3,13]. The frequency dependence of the refractive index reveals the S 0 -S 1 absorption peak at 540 nm and the absorption shoulder at 510 nm [14].…”

Section: Resultsmentioning

confidence: 99%

Concentration-dependent absorption and emission behaviour of a pyrimidonecarbocyanine dye in hexafluoroisopropanol

et al. 1987

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Refractive-index measurement of absorbing condensed media

Cited by 52 publications

References 21 publications

Third-order nonlinear susceptibilities of dye solutions determined by third-harmonic generation

Third-order nonlinear susceptibilities of dye solutions determined by third-harmonic generation

Absorption as a selective mechanism in surface plasmon resonance fiber optic sensors

Concentration-dependent absorption and emission behaviour of a pyrimidonecarbocyanine dye in hexafluoroisopropanol

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