Observing lateral temperature and refractive index profiles in an optically pumped midinfrared laser through temporally and spatially resolved spectra

1997 ◽  
Vol 71 (21) ◽  
pp. 3054-3056 ◽  
Author(s):  
Chi Yan ◽  
Donald L. McDaniel ◽  
Charles E. Moeller ◽  
Michael D. Falcon ◽  
Donald M. Gianardi
Keyword(s):  
Refractive Index ◽  
Optically Pumped ◽  
Spatially Resolved ◽  
Lateral Temperature

Single-molecule spectromicroscopy: a route towards sub-wavelength refractometry

2015 ◽  
Vol 184 ◽  
pp. 263-274 ◽  
Author(s):  
T. A. Anikushina ◽  
M. G. Gladush ◽  
A. A. Gorshelev ◽  
A. V. Naumov
Keyword(s):  
Refractive Index ◽  
Single Molecule ◽  
Low Temperatures ◽  
Radiative Lifetime ◽  
Spatially Resolved ◽  
Local Fluctuations ◽  
Novel Approach ◽  
Spectral Linewidth ◽  
Spatial Fluctuations ◽  
Sub Wavelength

We suggest a novel approach for spatially resolved probing of local fluctuations of the refractive index n in solids by means of single-molecule (SM) spectroscopy. It is based on the dependence T1(n) of the effective radiative lifetime T1 of dye centres in solids on n due to the local-field effects. Detection of SM zero-phonon lines at low temperatures gives the values of the SM natural spectral linewidth (which is inversely proportional to T1) and makes it possible to reveal the distribution of the local n values in solids. Here we demonstrate this possibility on the example of amorphous polyethylene and polycrystalline naphthalene doped with terrylene. In particular, we show that the obtained distributions of lifetime limited spectral linewidths of terrylene molecules embedded into these matrices are due to the spatial fluctuations of the refractive index local values.

scholarly journals Spatially Resolved Cross-Linking Characterization by Imaging Low-Coherence Interferometry

Sensors ◽  
2019 ◽  
Vol 19 (5) ◽  
pp. 1152 ◽  
Author(s):  
Christopher Taudt ◽  
Bryan Nelsen ◽  
Elisabeth Rossegger ◽  
Sandra Schlögl ◽  
Edmund Koch ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Thickness ◽  
Information Acquisition ◽  
Cross Linking ◽  
Imaging Spectrometer ◽  
Low Coherence ◽  
Spatially Resolved ◽  
Low Coherence Interferometry ◽  
Error Estimations ◽  
Phase Data

A method to characterize cross-linking differences in polymers such as waveguide polymers has been developed. The method is based on the scan-free information acquisition utilizing a low-coherence interferometer in conjunction with an imaging spectrometer. By the introduction of a novel analyzing algorithm, the recorded spectral-phase data was interpreted as wavelength-dependent optical thickness which is matchable with the refractive index and therefore with the degree of cross-linking. In the course of this work, the method was described in its hardware and algorithmic implementation as well as in its accuracy. Comparative measurements and error estimations showed an accuracy in the range of 10−6 in terms of the refractive index. Finally, photo-lithographically produced samples with laterally defined cross-linking differences have been characterized. It could be shown, that differences in the optical thickness of ±1.5 μm are distinguishable.

Spatially resolved measurement of femtosecond laser induced refractive index changes in transparent materials

2012 ◽  
Vol 37 (14) ◽  
pp. 3003 ◽  
Author(s):  
René Berlich ◽  
Jiyeon Choi ◽  
Clarisse Mazuir ◽  
Winston V. Schoenfeld ◽  
Stefan Nolte ◽  
...  
Keyword(s):  
Refractive Index ◽  
Femtosecond Laser ◽  
Spatially Resolved ◽  
Index Changes ◽  
Transparent Materials

scholarly journals Spatially resolved cross-sectional refractive index profile of fs laser–written waveguides using a genetic algorithm

2019 ◽  
Vol 27 (3) ◽  
pp. 2488 ◽  
Author(s):  
Antoine Drouin ◽  
Pierre Lorre ◽  
Jean-Sébastien Boisvert ◽  
Sébastien Loranger ◽  
Victor Lambin Iezzi ◽  
...  
Keyword(s):  
Genetic Algorithm ◽  
Refractive Index ◽  
Refractive Index Profile ◽  
Index Profile ◽  
Cross Sectional ◽  
Spatially Resolved ◽  
Fs Laser

Application of Micro-Schlieren Technique to Quantitative Analysis of Mass Transport in a Micromixer

2011 ◽  
Author(s):  
Tzu-hsun Hsiao ◽  
Chen-li Sun
Keyword(s):  
Refractive Index ◽  
Mass Transport ◽  
Concentration Gradient ◽  
Valuable Insight ◽  
Refractive Index Gradient ◽  
Aqueous Methanol ◽  
Full Field ◽  
Schlieren Technique ◽  
Spatially Resolved ◽  
Index Gradient

In this study, we develop a micro-schlieren analysis methodology to facilitate measurement of inhomogeneities in a micromixer. As a first step, calibration procedures are performed by mixing dilute aqueous methanol and water in a T-microchannel in order to obtain the relation between the refractive index gradients and pixel grayscale values. Knowing the influences of concentration in the refractive index of aqueous methanol solution, we are able to associate pixel grayscale values with the concentration gradient along the cross-stream axis. For refractive index gradient larger than 130 m−1, the calibration curve shows great linearity, setting the sensitivity limit of our quantitative micro-schlieren system to 2 × 104 m−1 for concentration gradient. We then implement this methodology to examine the mixing behavior in a microfluidic oscillator. The results prove that the micro-schlieren technique is able to provide spatially-resolved, noninvasive, full-field transient measurements and offer a valuable insight into the microscale mass transport phenomena that other methods fail to deliver. While the micro-schlieren technique is directly linked to the measurement of refractive index gradient, the present methodology can be extended to other scalar quantitations that are related to the variation of refractive index in the future.

Fabrication of refractive index and relief gratings in polymer films for DFB lasers

2001 ◽  
Vol 708 ◽  
Author(s):  
T. Kavc ◽  
G. Langer ◽  
W. Kern ◽  
G. Kranzelbinder ◽  
E. Toussaere ◽  
...  
Keyword(s):  
Refractive Index ◽  
Laser Irradiation ◽  
Surface Relief ◽  
Modulation Depth ◽  
Laser Action ◽  
Optically Pumped ◽  
Selective Functionalization ◽  
Recording Material ◽  
Dfb Laser ◽  
Surface Relief Gratings

ABSTRACTA styrene copolymer of 4-vinylbenzyl thiocyanate (PST-co-VBT) was employed as recording material for optical interference patterns with periods ∧ < 1 μm. Using lower intensity laser irradiation (4 mJ cm-2, λ = 266 nm), refractive index gratings were produced in PST-co-VBT by an UV induced photoisomerization SCN - NCS. Subsequent modification of the patterns with gaseous amines yielded surface relief gratings via the formation of derivatives of thiourea. Laser irradiation with higher pulse energies (7 mJ cm-2, λ = 266 nm) directly produced surface relief gratings (modulation depth 30 nm). These gratings were also reactive towards amine reagents and allowed a selective functionalization of the grooves of the relief (“reactive gratings”). Optically inscribed gratings in PST-co-VBT were employed as optical resonators for distributed feedback (DFB) lasing. With a laser dye (DCM) dissolved in PST-co-VBT, optically pumped DFB laser action was observed after inscribing index and relief gratings. The pumping threshold for lasing Ith was 250 nJ cm-2 at λ = 532 nm.

scholarly journals Radial gradient refractive index (GRIN) infrared lens based on spatially resolved crystallization of chalcogenide glass

2020 ◽  
Vol 10 (4) ◽  
pp. 860 ◽  
Author(s):  
Enora Lavanant ◽  
Laurent Calvez ◽  
François Cheviré ◽  
Mathieu Rozé ◽  
Thomas Hingant ◽  
...  
Keyword(s):  
Refractive Index ◽  
Chalcogenide Glass ◽  
Radial Gradient ◽  
Spatially Resolved ◽  
Gradient Refractive Index

scholarly journals Low-cost, open-access refractive index mapping of algal cells using the transport of intensity equation

2019 ◽  
Author(s):  
Stephen Grant ◽  
Kyle Richford ◽  
Heidi Burdett ◽  
David McKee ◽  
Brian R. Patton
Keyword(s):  
Refractive Index ◽  
Biological Samples ◽  
Low Cost ◽  
Algal Species ◽  
Spatially Resolved ◽  
Potential Applications ◽  
Index Mapping ◽  
Transport Of Intensity Equation ◽  
Open Source Hardware ◽  
Species Being

AbstractPhase contrast microscopy allows stain free imaging of transparent biological samples. One technique, using the transport of intensity equation (TIE), can be performed without dedicated hardware by simply processing pairs of images taken at known spacings within the sample. The resulting TIE images are quantitative phase maps of unstained biological samples. Therefore, spatially resolved refractive index information can also be determined.Using low-cost, open-source hardware, we applied the TIE to living algal cells to measure their refractive index. We obtained refractive index values that were repeatable within species and differed by distinct amounts depending on the species being measured. We suggest TIE imaging as a method of discrimination between different algal species and, potentially, non-biological materials, based on refractive index. Potential applications in biogeochemical modelling and climate sciences are suggested.

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