掺铒纳米晶与聚合物键合比例对光波导放大器增益性质的影响

Effect of Bonding Ratio of Erbium-doped Nanocrystals to Polymers on Gain Properties of Optical Waveguide Amplifier

将掺铒纳米晶与甲基丙烯酸甲酯(MMA)单体共聚获得的复合聚合物可用作聚合物光波导放大器的增益介质。器件的增益性能与复合聚合物中的纳米粒子浓度密切相关。本文利用高温热分解法成功制备了尺寸均匀的β-NaLu_(50%)Y_(30%)F_(4)∶18%Yb^(3+),2%Er^(3+)纳米晶。纳米晶尺寸约16 nm,表面修饰有不饱和基团,因此可以与MMA共聚合得到纳米粒子-聚甲基丙烯酸甲酯(NPs-PMMA)纳米复合材料。通过将纳米粒子的掺杂浓度分别调整为0.1,0.15,0.25 mmol,制备了三组不同键合比例的复合聚合物。下转换发射光谱和透过光谱测试分析表明,随着键合的纳米晶浓度升高,复合聚合物发光强度逐渐提高,但近红外区的光透过率略微下降。使用这三组复合聚合物材料制备的倒脊型光波导放大器,在1550 nm处,器件的相对增益分别为3,3.46,5.61 dB,插入损耗分别为19.20,25.00,26.53 dB。该结果说明,虽然高掺杂浓度的稀土纳米晶造成了散射损耗增加,却有效地提高了增益介质在C波段的发光强度和器件的相对增益。在本文实验中,增加纳米晶浓度带来的增益提高优于散射损耗的增加。

The nanocomposite,which is synthesized by copolymerizing erbium-doped nanocrystals and methyl methacrylate(MMA)monomer,can be used as the gain media to fabricate a polymer-based optical waveguide amplifier.The gain performance of this type device is closely related to the concentration of nanocrystals in the nanocomposite.In this paper,the uniform β-NaLu_(50%)Y_(30%)F_(4)∶18%Yb^(3+),2%Er^(3+)nanocrystals were successfully synthesized by the thermal decomposition method.The nanocrystals were about 16 nm and modified with unsaturated ligands on their surfaces.Therefore,the nanocrystals could be copolymerized with MMA to form nanoparticles-polymethyl methacrylate(NPs-PMMA)nanocomposite.Three groups of nanocomposites with different bonding ratios were prepared by adjusting the doping concentrations of nanoparticles to 0.1,0.15,0.25 mmol,respectively.The down-conversion emission and transmission spectra showed that with the increase of the bonding nanocrystal concentration,the luminescence intensity of the nanocomposites increased gradually,but the light transmittance in the near infrared region decreased slightly.A series of embedded waveguide amplifiers were fabricated based on these three nanocomposites.At 1550 nm,the relative gains of these devices were 3.00,3.46,5.61 dB,and the insertion losses were 19.20,25.00,26.53 dB,respectively.The results showed that even the scattering loss raised with the increase of nanocrystal concentration,the luminescence intensity of the gain media still enhanced and the relative gain improved in the series of devices in the C-band.In the experiment of this paper,increasing the concentration of the nanocrystals results in an advantage of the gain improvement over the scattering loss increase.