Second-harmonic generation in lithium niobate nanowires for local fluorescence excitation

作者：Sergeyev Anton^*; Geiss Reinhard; Solntsev Alexander S; Steinbrueck Andrea; Schrempel Frank; Kley Ernst Bernhard; Pertsch Thomas; Grange Rachel

来源：Optics Express, 2013, 21(16): 19012-19021.

DOI：10.1364/OE.21.019012

We study the nonlinear optical properties of lithium niobate (LiNbO3) nanowires (NWs) fabricated by a top-down ion beam enhanced etching method. First, we demonstrate generation and propagation of the second-harmonic (SH) light in LiNbO3 NWs of typical rectangular cross-sections of 400 x 600 nm(2) and length from 10 to 50 mu m. Then, we show local fluorescent excitation of 4%26apos;,6-diamidino-2-phenylindole (DAPI) dye with the propagated SH signal in standard concentrations as for biological applications. By measuring the detected average power of the propagated fundamental harmonic (FH) and the SH signal at the output of the NWs, we directly prove the dominating role of the SH signal over possible two-photon excitation processes with the FH in the DAPI dye. We estimate that 63 +/- 6 pW of the propagated SH average power is required for detectable dye excitation. Finally, we model the waveguiding of the SH light to determine the smallest NW cross-section (around 40x60 nm(2)) which is potentially able to excite fluorescence with a FH intensity below the cell damage threshold.

• 出版日期2013-8-12