Nonlinear spectroscopy in the near-field: time resolved spectroscopy and subwavelength resolution non-invasive imaging

Nanophotonics

article

Mahesh Namboodiri¹  Tahirzeb Khan¹  Khadga Karki¹  Mehdi Mohammad Kazemi¹  Sidhant Bom¹  Günter Flachenecker¹  Vinu Namboodiri¹  Arnulf Materny¹ 

[1] Center for Functional Materials and Nanomolecular Science, Jacobs University Bremen, Campus Ring 1

关键词: nonlinear optical spectroscopy;    femtosecond time-resolved spectroscopy;    scanning near-field optical microscopy;    organic semiconductor nanostructures;    transient absorption spectroscopy;    surface enhanced coherent anti-Stokes Raman scattering;   

DOI  :  10.1515/nanoph-2013-0044

学科分类：社会科学、人文和艺术（综合）

来源: De Gruyter

【 摘 要 】

The combination of near-field microscopy along with nonlinear optical spectroscopic techniques is presented here. The scanning near-field imaging technique can be integrated with nonlinear spectroscopic techniques to improve spatial and axial resolution of the images. Additionally, ultrafast dynamics can be probed down to nano-scale dimension. The review shows some examples for this combination, which resulted in an exciton map and vibrational contrast images with sub-wavelength resolution. Results of two-color femtosecond time-resolved pump-probe experiments using scanning near-field optical microscopy (SNOM) on thin films of the organic semiconductor 3,4,9,10 Perylenetetracarboxylic dianhydride (PTCDA) are presented. While nonlinear Raman techniques have been used to obtain highly resolved images in combination with near-field microscopy, the use of femtosecond laser pulses in electronic resonance still constitutes a big challenge. Here, we present our first results on coherent anti-Stokes Raman scattering (fs-CARS) with femtosecond laser pulses detected in the near-field using SNOM. We demonstrate that highly spatially resolved images can be obtained from poly(3-hexylthiophene) (P3HT) nano-structures where the fs-CARS process was in resonance with the P3HT absorption and with characteristic P3HT vibrational modes without destruction of the samples. Sub-diffraction limited lateral resolution is achieved. Especially the height resolution clearly surpasses that obtained with standard microCARS. These results will be the basis for future investigations of mode-selective dynamics in the near-field.

【 授权许可】

CC BY