光參量振盪器為三波長非線性光學下轉換系統，經常被使用在廣域的波段可調同調光源，因而在光通訊、光譜學、光學檢測及兆赫波產生等領域上有廣泛的應用。在鈮酸鋰晶體上，藉由使用準相位匹配技術，不但可以使光參量振盪器具有高度自由的波長設計範圍，並且也能利用最大非線性係數。 配合鈮酸鋰晶體具有的電光效應，能在單一鈮酸鋰晶片上外加y方向電場用以調控光參量訊號偏振態，對光參量訊號進行波長調變、窄頻、選頻等作用。 本實驗利用模擬退火演算法及極化反轉技術，成功將多波長電光偏振調制器及多波長光參量振盪器，整合為單一非週期極化反轉鈮酸鋰晶片，多波長光參量振盪器與電光偏振調制器設計中心波長為光通訊波段1540nm及1550nm，再無外加電場時能產生雙波長光參量振盪器，並能在外加y方向電場360V/mm及790V/mm時，能分別選擇1540nm及1550nm光參量振盪器訊號光，其頻寬分別為0.07nm及0.09nm，並且實驗結果與模擬結果相當符合，成功在鈮酸鋰晶體上實現光通訊波段的電光選頻積體光學元件。 ;An optical parametric oscillator (OPO) is a three-wave nonlinear wavelength down conversion system, which is often used as a wide band tunable coherent radiation source and thus has been widely used in optical communication, spectroscopy, optical inspection, and other applications. The use of the quasi-phase-matching (QPM) technique in lithium niobate (LiNbO3) crystals not only allows the OPO signals to be highly engineerable in a wide spectral range, but also largely enhances the conversion efficiency due to the access of the maximum nonlinear coefficient d33 of the crystal. By properly utilizing the electro-optic (EO) effect in a QPM LiNbO3, we can modulate the polarization state of an or multiple input waves, in which the spectrum and bandwidth of OPO signals can be changed, tailored, or/and selected when such an EO QPM polarization mode converter (PMC) is operated with the OPO. In this study, a multi-wavelength EO PMC and a multi-wavelength optical parametric down converter (OPDC) were successfully integrated in a single aperiodically poled lithium niobate (APPLN) chip. The OPDC and EO PMC were both designed to work at dual wavelengths 1540 nm and 1550 nm in an optical communication band. When this novel integrated APPLN crystal is operated in an optical resonator pumped by a Q-switched 1064-nm laser, we can generate the dual-wavelength signal (of ~0.5 nm linewidth) with this OPO system before any external electric field is applied to the APPLN. When applying electric fields of 360 V/mm and 790 V/mm to the APPLN device, we can select and oscillate only the 1540 nm and only the 1550 nm signals with linewidths of 0.07 nm and 0.09 nm, respectively, in the novel OPO system. The consistency of the simulation and the experimental results show that we have successfully demonstrated the world-first EO frequency selectable mutil-line OPO based on an integrated APPLN in the optical communication band.
