fig4

Figure 4. (A) Transmission spectrum of the stably poled KTN. (B) Polarization microscope image and corresponding d_eff distribution diagram (dark color represents positive and light color represents negative) of stably poled KTN in the y-z plane. (C) Schematic of the relationship between SHG (Type-I, at 830 nm FW) intensity and propagation distance under quasi-phase-matching, phase-mismatching, and real-space-matching. The intensity range is the same in both the upper and lower parts. Schematic of SHG change vs. fundamental wavelength (D) from 830 to 850 nm, with an interval of 5 nm, and (F) from 1,300 to 1,375 nm, with an interval of 25 nm. SHG spot patterns at (E) λ_ω = 830 and 850 nm, (G) λ_ω = 1,300 and 1,375 nm. The white dashed box encloses the SHG spots generated by the Type-I QPM process.