Sirtori C, Gmachl C, Capasso F, Faist J, Sivco D L, Hutchinson A L, Cho A Y
Opt Lett. 1998 Sep 1;23(17):1366-8. doi: 10.1364/ol.23.001366.
Laser waveguides based on surface plasmons at a metal-semiconductor interface have been demonstrated by use of quantum cascade (QC) lasers emitting in the 8-11.5-microm wavelength range. The guided modes are transverse magnetic polarized surface waves that propagate at the metal (Pd or Ti-Au)-semiconductor interface between the laser top contact and the active region without the necessity for waveguide cladding layers. The resultant structure has the advantages of a strong decrease in the total layer thickness and a higher confinement factor of the laser-active region compared with those of a conventional layered semiconductor waveguide, and strong coupling to the active material, which could be used in devices such as distributed-feedback lasers. These advantages have to be traded against the disadvantage of increased absorption losses. A peak output power exceeding 25 mW at 90 K and a maximum operating temperature of 150 K were measured for a QC laser with an emission wavelength lambda approximately 8 microm . At lambda approximately 11.5 microm the peak power levels are several milliwatts and the maximum operating temperature is 110 K.
利用在8 - 11.5微米波长范围内发射的量子级联（QC）激光器，已证明了基于金属 - 半导体界面表面等离子体激元的激光波导。导模是横向磁极化表面波，其在激光顶部接触层与有源区之间的金属（钯或钛 - 金） - 半导体界面处传播，无需波导包层。与传统的层状半导体波导相比，所得结构具有总层厚度大幅减小以及激光有源区限制因子更高的优点，并且与有源材料有强耦合，可用于诸如分布反馈激光器等器件中。这些优点必须与吸收损耗增加的缺点相权衡。对于发射波长λ约为8微米的QC激光器，在90 K时测得峰值输出功率超过25 mW，最大工作温度为150 K。在λ约为11.5微米时，峰值功率水平为几毫瓦，最大工作温度为110 K。
