Cheng Pi-Ju, Chiang Chih-Kai, Chung Yi-Cheng, Tien Chung-Hao, Lin Tzy-Rong
Research Center for Applied Sciences, Academia Sinica, 11529 Taipei, Taiwan ; Department of Photonics, National Chiao Tung University, 30010 Hsinchu, Taiwan.
Institute of Optoelectronic Sciences, National Taiwan Ocean University, 20224 Keelung, Taiwan.
Nanoscale Res Lett. 2014 Nov 28;9(1):641. doi: 10.1186/1556-276X-9-641. eCollection 2014.
We theoretically analyze nanowire-based hybrid plasmonic nanocavities on thin substrates at visible wavelengths. In the presence of thin suspended substrates, the hybrid plasmonic modes, formed by the coupling between a metal nanowire and a dielectric nanowire with optical gain, exhibit negligible substrate-mediated characteristics and overlap better with the gain region. Consequently, the confinement factor of the guided hybrid modes is enhanced by more than 42%. However, the presence of significant mirror loss remains the main challenge to lasing. By adding silver coatings with a sufficient thickness range on the two end facets, we show that the reflectivity is substantially enhanced to above 50%. For a coating thickness of 50 nm and cavity length of about 4 μm, the quality factor is above 100.
我们从理论上分析了基于纳米线的混合等离子体纳米腔在可见波长下于薄衬底上的情况。在存在薄悬浮衬底的情况下，由具有光学增益的金属纳米线和介质纳米线之间的耦合形成的混合等离子体模式，呈现出可忽略不计的衬底介导特性，并且与增益区域的重叠更好。因此，导模混合模式的限制因子提高了42%以上。然而，显著的镜面损耗的存在仍然是实现激光发射的主要挑战。通过在两个端面添加具有足够厚度范围的银涂层，我们表明反射率大幅提高到50%以上。对于涂层厚度为50nm且腔长约为4μm的情况，品质因数高于100。
