Fig. 1. CdS NBs. (a) Scanning electron microscope image of upper face (scar bar, 1 µm). (b) Scanning electron microscope image of side face (scar bar, 5 µm). (c) Optical microscope image (scar bar, 10 µm).

Fig. 2. Schematic diagram of the experiment. CdS NB is placed across a slit of two MgF₂ to avoid influence from substrates.

Fig. 3. Emitting angle determined by the phase matching condition.

Fig. 4. (a) Optical microscope image of a 2-µm-wide CdS NB with a height of 200 ± 10 nm (scar bar, 50 µm). Inset shows simulated profiles of the fundamental and second-order modes inside an NB at a wavelength of 1064 nm (scar bar, 1 µm). In the FDTD simulation, the width is 2 µm, and the height is 200 nm. (b) TSH interference patterns for the CdS NB with 1064 nm CW light input. (c) Optical microscope image of a 300 nm diameter nanowire (scar bar, 50 µm). Inset shows simulated profile of the first and second-order modes at a wavelength of 1064 nm (scar bar, 300 nm). In the simulation, the nanowire has a hexagonal cross section, which agrees with the reality. The side-to-side diameter is 300 nm. (d) TSH patterns for the nanowire with 1064 nm CW light input.

Fig. 5. (a) Measured spectrum of TSH signal. (b) Intensity of the TSH signal with different input power. (c) Extracted intensity profile for the TSH signal along the axis of the NB, corresponding to the inside image of Fig. 4(b). (d) Corresponding FFT spectrum. The arrows indicate the first five peaks in the spectrum.

Fig. 6. Δn_eff and D with different surrounding refractive indices. Inside image shows calculated effective index for the fundamental mode and the second-order mode, respectively. The width of the NB is 2 µm.The height of the NB is 200 nm. The pumping wavelength is 1064 nm.

Fig. 7. (a) Δn_eff and D with different widths of NBs. The pumping wavelength is 1064 nm. (b) Δn_eff and D at different wavelengths for a 2-µm-wide CdS NB. The height of the NB is 200 nm.

Table 1. Comparison between Calculated Results of Modal Interference and Experimental Results^a

Table 2. Calculated Results of Modal Interference with Different Heights of NBs