1.5-Mu M-Band Tunable Wavelength Conversion Based On Fan-Out Grating In Qpm-Ln

In this paper, we demonstrated the tunable 1.5-mu m-band wavelength conversion based on cascaded second order nonlinear processes "SHG+DFG" by fan-out grating in lithium niobate waveguide for the first time. We fabricated the waveguide by annealed proton exchange in periodically poled LiNbO3 (PPLN). The device used in this experiment is 4 cm long, has a QPM period from 14.8 mu m to 15.2 mu m, waveguide width of 12 mu m, proton exchange depth of 0.7 mu m, and was annealed for 32h at 350 degrees C. After proton exchange in pure benzoic acid using a SiO2 mask, the substrate was annealed in an oxygen atmosphere. The wavelength of signal light was set at 1551.3nm. The wavelengths of tunable pump lights we used in experiment were 1543.2 and 1556.2 nm, and the corresponding grating periods were 14.87 mu m and 15.03 mu m, respectively. The temperature was set at 100.5 degrees C to avoid photo refractive damage and to match the QPM peaks to the pump wavelengths. The conversion efficiency was about 10dB to be expected with the pump power 175mW in a similar device with a slightly different QPM period and operated at 125 degrees C.