Intersubband Optoelectronic Devices in the 1.55um Range

最近由美国国家科学基金会资助的麻省理工学院的研究表明，InGaA1As量子阱，隧道势垒异质结构可以在子带间能级分离（n = 1到n = 2）高达0.8 eV （1.55 um）的情况下产生，并且具有TE-和TM-的光学活性。拟议的研究项目建立在这些结果的基础上，并将侧重于(1)开发具有更大水平间隔的结构；(2)利用飞秒脉冲探测技术测量量子阱的上态寿命；(3)研究了子带间吸收峰附近的光学性质（折射率和吸收系数），以及偏置和种群引起的这些性质的变化；(4)在波导几何光电器件（调制器、开关和探测器）中结合量子阱、隧道势垒异质结构。量子阱中的激发态寿命本质上是非常短的（并且可以使用它们的隧道势垒进一步缩短），因此预计这项研究将导致实现比目前在1.5 um光谱范围内可用的更快，更低功率的器件。预计这些器件将表现出优异的温度稳定性，因为它们是基于子带间工艺，而不是基于带对带工艺。＊＊＊

9408155 Fonstad Recent NSF-funded research at MIT has shown that InGaA1As quantum- well, tunnel-barrier heterostructures can be produced with intersubband energy level separations (n = 1 to n = 2) as large as 0.8 eV (1.55 um) and with TE-, as well as TM-, optical activity. The proposed research project builds on these results, and will focus (1) on developing structures with even larger level separations; (2) on using femto-second pulse-probe techniques to measure upper state lifetimes in quantum wells; (3) on studying the optical properties (index of refraction and absorption coefficient) in the vicinity of the intersubband absorption peaks, and on studying bias- and population-induced changes in these properties; and (4) on incorporating quantum-well, tunnel-barrier heterostructures in waveguide geometry optoelectronic devices (modulators, switches, and detectors). The excited state lifetimes in quantum wells are inherently very short (and can be shortened further using their tunnel barriers) so it is anticipated that this research will lead to the realization of faster, lower power devices than are presently available in the 1.5 um spectral range. It is also anticipated that these devices will show superior temperature stability because they are based on intersubband, rather than band-to-band processes. ***