Noise Analysis of Second-Harmonic Generation in Undoped and MgO-Doped Periodically Poled Lithium Niobate

[摘要] Noise characteristics of second-harmonic generation (SHG) inperiodically poled lithium niobate (PPLN) using the quasiphasematching (QPM) technique are analyzed experimentally. In theexperiment, a0.78 μmsecond-harmonic (SH) wave was generated whena 1.56 μmfundamental wave passed through a PPLN crystal (bulk orwaveguide). The time-domain and frequency-domain noisecharacteristics of the fundamental and SH waves were analyzed. Byusing the pump-probe method, the noise characteristics of SHG werefurther analyzed when a visible light (532 nm) and an infraredlight (1090 nm) copropagated with the fundamental light,respectively. The noise characterizations were also investigatedat different temperatures. It is found that for the bulk andwaveguide PPLN crystals, the SH wave has a higher relative noiselevel than the corresponding fundamental wave. For the samefundamental wave, the SH wave has lower noise in a bulk crystalthan in a waveguide, and in MgO-doped PPLN than in undoped PPLN. The 532 nm irradiation can lead to higher noise in PPLN than the1090 nm irradiation. In addition, increasing temperature of devicecan alleviate the problem of noise in conjunction with thephotorefractive effect incurred by the irradiation light. This ismore significant in undoped PPLN than in MgO-doped one.

[学科分类] 电子、光学、磁材料