Lithium niobate thin films (TFLN), with the significant advantages of wide transparency window, high refractive index, and large acousto-optic/electro-optic/non-linear optical coefficients, have emerged as a promising material platform for the fabrication of high-performance photonic integrated devices for both classical and quantum applications, where photonics devices, such as low-loss waveguides, high-quality microresonators% 2c kecepatan tinggi modulator% 2c dan efisiensi tinggi optik frekuensi konverter, memiliki sekarang menjadi terwujud. Namun, kristal tunggal lithium niobate kekurangan efektif pendaran dan deteksi kemampuan.
Baru-baru ini, lithium niobate crystals doped with rare-earth ions have started to be a practical solution for realizing the optical gain function of TFLN platforms, and rare-earth-ion doped optically pumped microlasers have been experimentally demonstrated. Rare earth ion doped lasers have the advantages of wide bandwidth, polarization insensitivity, high applicable temperature and good compatibility. In addition, rare-earth ion-doped lasers are more promising in achieving high power output, mode-locked operation, and coherent beam combinations. Namun, currently, all rare-earth ion-doped TFLN lasers are optically pumped by external lasers connected using optical fibers, which hinders the development of integrated photonics on TFLNs.
Baru-baru ini, a compact hybrid lithium niobate micro-ring laser was demonstrated by Prof. Cheng Ya's team at East China Normal University. Figure 1 shows a schematic diagram of the proposed compact hybrid lithium niobate micro-ring laser pumped by a semiconductor laser, which consists of a commercially available CoS-packaged semiconductor laser and a high-Q Er3 plus -doped micro-ring. The alignment between the input port of the micro-ring and the output port of the CoS-encapsulated semiconductor laser tube is reached by a {{1{0}}axis alignment system with an adjustable accuracy of 10 nm, which in turn enables efficient optical coupling. To achieve stable and tight bonding, UV adhesive is applied by a dispenser and the two chips are fixed by UV irradiation. The key to this work is that the Er3 plus -doped micro-ring has a high Q value at the pump wavelength of the semiconductor laser. As shown in Fig. 2, the center wavelength of the pump laser of the semiconductor is 976.24 nm, and at this wavelength, the Q value of the micro-ring is 7.3×105. The center wavelength of the laser produced by the Er3 plus -doped micro-ring under the pompa cahaya is 1531.27 nm, and the linewidth of the laser is 0.05 nm, and the single-mode laser emission is attributable to the mode-dependent loss and gain competition. In addition, the linewidth of the emitted laser is two orders of magnitude narrower than the linewidth of the pump light generated by the CoS-packaged semiconductor laser.
Gbr. 1. (a) Skematik diagram of a compact hybrid lithium niobate micro-ring laser consisting of a CoS-packaged semiconductor laser and a high-Q Er:TFLN micro-ring laser. (b) Top view of the compact hybrid lithium niobate micro-ring laser. (c) Close-up photo under optical microscope of the interface between the the CoS-encapsulated semiconductor laser and the Er:TFLN micro-ring.
Fig. 2. (a) Q of the micro-ring at 976 nm is 7.3 × 105. (b) Q of the micro-ring at 1531 nm is 1.85 × 105. (c) Spectrum near the center wavelength of the semiconductor laser. (d) Spectrum near the wavelength of the Er3 plus -doped micro-ring emitting a single-frequency laser at 1531.27 nm with a linewidth of 0.05 nm.
Ini bekerja mengeksplorasi a kuat hibrida lithium niobate cincin mikro laser sumber itu memiliki potensi aplikasi in koheren optik komunikasi dan presisi metrologi , dan hasil adalah diterbitkan online in OpticsLetters.
