Third harmonic generation and microscopy, enhanced by a bias harmonic field

OPTICS COMMUNICATIONS

卷:457

Article

Stock, Christian¹  Zlatanov, Kaloyan²  Halfmann, Thomas¹ 

[1] Tech Univ Darmstadt, Inst Angew Phys, Hsch Str 6, D-64289 Darmstadt, Germany

[2] Bulgarian Acad Sci, Inst Solid State Phys, Tsarigradsko Chaussee 72, Sofia 1784, Bulgaria

关键词: Nonlinear microscopy;    Third harmonic generation;    Ultrafast nonlinear optics;    Dispersion;   

DOI  :  10.1016/j.optcom.2019.124660

来源: Elsevier

【 摘 要 】

We present strong enhancements of the signal yield in third harmonic generation microscopy by seeding the optically nonlinear sample with some intensity at the third harmonic wavelength, in addition to the driving fundamental beam. By applying a third harmonic bias pulse with a power of less then 0.1% of the fundamental beam, we boost the signal yield by more than a factor of 3000, compared to the conventional third harmonic signal from the microscopy sample. The signal enhancement is most pronounced at low laser intensity and/or weak nonlinear susceptibilities. This makes the concept particularly suitable to improve the signal-to-noise ratio from samples with weak signals, e.g., as typical for applications of nonlinear microscopy. Moreover, we demonstrate improved spatial resolution in beam propagation direction by more than an order of magnitude. This exploits the dependence of our approach for enhanced third harmonic generation from inevitable dispersion in the sample. The improvement is most evident in cases, where the sample geometry allows only weak focusing.

【 授权许可】

Free