Additions and Corrections Cite This: ACS Photonics XXXX, XXX, XXX−XXX
Correction to Plasmonically Enhanced Kerr Frequency Combs Rigoberto Castro-Beltrán, Vinh Diep, Soheil Soltani, Eda Gungor, and Andrea M. Armani* ACS Photonics 2017, 4 (11), 2828−2834. DOI: 10.1021/acsphotonics.7b00808
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t has been brought to our attention that we incorrectly applied the material optical constants for the nonlinear refractive index n2 value of polyethylene glycol (PEG) presented in ref 36. To remedy this error, we have performed Z-scan measurements of the exact materials used in our experiments. Specifically, we performed Z-scan measurements on solutions of gold nanorods functionalized with either PEG (PEG-NR) or CTAB (CTAB-NR). The findings from the Z-scan results are below. The Z-scans confirm the larger n2 values for the PEG-NR solutions, and that the n2 values are dependent on the surface coating. Both findings are consistent with the hypothesis presented in the original paper. The authors apologize for any confusion that this error caused the scientific community.
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Figure 2. Normalized closed-aperture z-scan plots of PEG-NR and CTAB-NR complex samples at the same molar concentration.
Z-SCAN MEASUREMENTS To calibrate the Z-scan setup and ensure correct operation, a carbon disulfide (CS2) standard is measured. Figure 1 shows the representative experimental result of the Z-scan close-aperture configuration. The obtained n2 = 2.86 × 10−15 cm2 W1− value is in good agreement with previous values.
Table 1. Values of the n2 through the Z-scan Techniquea sample
n2 (cm2 W−1)
CS2 PEG-NR methanol CTAB-NR H2O
2.86 × 10−15 1.32 × 10−14 3.9 × 10−16 −1.021 × 10−15 7.33 × 10−16
a
The Z-scan measurements were carried out using pulses of 80 fs duration centered at 800 nm. The pulse trains with 1 kHz repetition rate have been generated by a Ti:sapphire regenerative amplifier.
Figure 1. CS2 standard nonlinear optical material. Normalized transmittance using the close-aperture Z-scan scheme with fs laser (λ = 800 nm, t = 80 fs, 1 kHz).
Z-scan measurements of the PEG-NR and CTAB-NR solutions were performed at the same molar concentration and under the same peak intensity (Figure 2). Z-scan measurements of the solvents were also performed. Both present opposite behavior and ∼1 order of magnitude of difference in their n2 values. PEG-NR complex sample shows the stronger nonlinear refraction with a magnitude n2 ∼ 10−14 cm2 W1−. This value is approximately 2 orders of magnitude larger compared to silica (n2 ∼ 10−16 cm2 W1−). Table 1 summarizes the NL refractive indices determined for our complex samples, their corresponding solvents, and the CS2 standard material. © XXXX American Chemical Society
Received: July 9, 2018
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DOI: 10.1021/acsphotonics.8b00923 ACS Photonics XXXX, XXX, XXX−XXX
