Laser heating of near-field tips

Kurpas, Vera V.; Libenson, Mikhail N.; Martsinovsky, George A.

doi:10.1016/0304-3991(95)00098-4

Cited by 14 publications

(9 citation statements)

References 2 publications

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“…It has been suggested that the increased efficiencies of these probes may reduce sample heating. 19,20 On the contrary, our measurements show that these probes have nearly identical sample heating profiles with output power as NSOM probes fabricated using the pulling method. While the heating is similar, we find that the power at which tip failure occurs is much higher for etched tips than for pulled probes.…”

Section: Introductioncontrasting

confidence: 42%

“…3,6,26 The higher throughput efficiencies of etched NSOM probes has led to speculation that sample heating may be reduced, making chemically etched probes more amenable for use with temperature sensitive samples. 19,20 Previously, we used a thermochromic polymer to characterize the sample heating experienced directly from pulled NSOM probes. 18 The inset in Fig.…”

Section: Resultsmentioning

confidence: 99%

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Characterization of power induced heating and damage in fiber optic probes for near-field scanning optical microscopy

Dickenson

Erickson

Mooren

et al. 2007

Review of Scientific Instruments

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Tip-induced sample heating in near-field scanning optical microscopy ͑NSOM͒ is studied for fiber optic probes fabricated using the chemical etching technique. To characterize sample heating from etched NSOM probes, the spectra of a thermochromic polymer sample are measured as a function of probe output power, as was previously reported for pulled NSOM probes. The results reveal that sample heating increases rapidly to ϳ55-60°C as output powers reach ϳ50 nW. At higher output powers, the sample heating remains approximately constant up to the maximum power studied of ϳ450 nW. The sample heating profiles measured for etched NSOM probes are consistent with those previously measured for NSOM probes fabricated using the pulling method. At high powers, both pulled and etched NSOM probes fail as the aluminum coating is damaged. For probes fabricated in our laboratory we find failure occurring at input powers of 3.4± 1.7 and 20.7± 6.9 mW for pulled and etched probes, respectively. The larger half-cone angle for etched probes ͑ϳ15°for etched and ϳ6°for pulled probes͒ enables more light delivery and also apparently leads to a different failure mechanism. For pulled NSOM probes, high resolution images of NSOM probes as power is increased reveal the development of stress fractures in the coating at a taper diameter of ϳ6 m. These stress fractures, arising from the differential heating expansion of the dielectric and the metal coating, eventually lead to coating removal and probe failure. For etched tips, the absence of clear stress fractures and the pooled morphology of the damaged aluminum coating following failure suggest that thermal damage may cause coating failure, although other mechanisms cannot be ruled out.

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Section: Introductioncontrasting

confidence: 42%

Section: Resultsmentioning

confidence: 99%

Characterization of power induced heating and damage in fiber optic probes for near-field scanning optical microscopy

Dickenson

Erickson

Mooren

et al. 2007

Review of Scientific Instruments

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“…The temperature profiles along the aluminum-coated fiber tip due to local heating were calculated or measured by several groups in the mid-1990s [43][44][45][46][47][48]. The heating was shown to be strongly dependent on the taper angle of the tip: decreasing with increasing taper angle [44,48]. The temperature coefficients varied from 20 K m −1 W −1 for a tip with large cone angle to 60 K m −1 W −1 for the narrow one [44].…”

Section: Introductionmentioning

confidence: 99%

“…The measured temperature increase at a distance of 70 μm from the aperture (apex) was linear with the input light power until the coating was damaged [43,44]. The probe could be damaged as a result of thermal stress caused by different thermal expansions of the fiber and aluminum coating [43][44][45][46][47][48]. La Rosa also measured the two-time-constant tip expansion in later work [49].…”

Section: Introductionmentioning

confidence: 99%

Near-field thermal transport in a nanotip under laser irradiation

Chen

Wang

2011

Nanotechnology

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We report on a systematic study of highly enhanced optical field and its induced thermal transport in nanotips under laser irradiation. The effects on electric field distribution caused by curvature radius, tip aspect ratio, and polarization angle of the incident laser are studied. Our Poynting vectors' study clearly shows that when a laser interacts with a metal tip, it is bent around the tip and concentrated under the apex, where extremely high field enhancement appears. This phenomenon is more like a liquid flow being forced/squeezed to go through a narrow channel. As the tip-substrate distance increases, the peak field enhancement decreases exponentially. A shift of field peak position away from the tip axis is observed. For the incident light, only its component along the tip axis direction has a contribution to the electric field enhancement under the tip apex. The optimum tip apex radius for field enhancement is about 9 nm when the half taper angle is 10°. For a tip with a fixed radius of 30 nm, field enhancement increases with the half taper angle when it is less than 25°. The thermal transport inside the nanoscale tungsten tips due to absorption of incident laser light is explored using the finite element method. A small fraction of light penetrates into the tip. As the polarization angle or apex radius increases, the peak apex temperature decreases. The peak apex temperature goes down as the half taper angle increases, even though the mean laser intensity inside the tip increases, revealing a very strong effect of the taper angle on thermal transport.

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“…It was shown [42] that the temperature distribution in a probe strongly depends on the probe microgeometry and on the field distribution near the probe apex. In conventional probe, there exist a loop of magnetic field and a node of electric field at the aperture plane.…”

Section: Probe Heating Upmentioning

confidence: 99%