Terahertz quantum cascade lasers operating up to ∼ 200 K with optimized oscillator strength and improved injection tunneling
Terahertz quantum cascade lasers operating up to ∼ 200 K with optimized oscillator strength and improved injection tunneling
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DOI：
10.1364/oe.20.003866
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发表时间：
2012-02-13
期刊：
影响因子：
3.8
通讯作者：
Liu, H. C.
中科院分区：
文献类型：
--
作者：
Fathololoumi, S.;Dupont, E.;Liu, H. C.
通过优化基于共振声子的三阱设计的激光跃迁振子强度，实现了太赫兹量子级联激光器199.5K的温度性能新记录。发现最佳振子强度0.58大于Kumar等人的先前记录（0.41）。94，131105（2009）]。隧穿势垒厚度的选择是用简化的密度矩阵模型确定的，该模型收敛于比先前探索的更高的隧穿耦合强度，并且在设计电场下跨注入和提取势垒的状态几乎完美对齐。在8 K时，器件的阈值电流密度为1 kA/cm（2），峰值输出功率约为38 mW，随着偏压的增加，激光频率从2.6 THz蓝移到2.85 THz。波长蓝移到3.22 THz，更接近199.5 K的最大工作温度，这对应于在bar Ω/kappa（B）上类似于1.28（h）。激光频率的电压依赖性与两个子带间跃迁的斯塔克效应有关，并与通过蒙特卡罗方法获得的模拟增益谱进行了比较。(C)2012美国光学学会
A new temperature performance record of 199.5 K for terahertz quantum cascade lasers is achieved by optimizing the lasing transition oscillator strength of the resonant phonon based three-well design. The optimum oscillator strength of 0.58 was found to be larger than that of the previous record (0.41) by Kumar et al. [Appl. Phys. Lett. 94, 131105 (2009)]. The choice of tunneling barrier thicknesses was determined with a simplified density matrix model, which converged towards higher tunneling coupling strengths than previously explored and nearly perfect alignment of the states across the injection and extraction barriers at the design electric field. At 8 K, the device showed a threshold current density of 1 kA/cm(2), with a peak output power of similar to 38 mW, and lasing frequency blue-shifting from 2.6 THz to 2.85 THz with increasing bias. The wavelength blue-shifted to 3.22 THz closer to the maximum operating temperature of 199.5 K, which corresponds to similar to 1.28 (h) over bar omega/kappa(B). The voltage dependence of laser frequency is related to the Stark effect of two intersubband transitions and is compared with the simulated gain spectra obtained by a Monte Carlo approach. (C) 2012 Optical Society of America