Intersubband Optoelectronic Devices in the 1.55um Range

麻省理工学院最近NSF资助的研究表明，InGaA 1As量子阱、隧道势垒异质结构可以产生为具有大至0.8eV（1.55 μ m）的子带间能级间隔（n = 1至n = 2）和TE-以及TM-光学活性。 在此基础上，本研究计划将着重于：（1）发展更大能级间隔的结构;（2）利用飞秒脉冲探测技术测量量子威尔斯中的上能级寿命;（3）光学性质的研究（折射率和吸收系数）在子带间吸收峰附近，以及研究偏压和人口引起的这些性质的变化;以及（4）在波导几何光电器件（调制器、开关和检测器）中结合量子阱、隧道势垒异质结构。 量子威尔斯中的激发态寿命固有地非常短（并且可以使用它们的隧道势垒进一步缩短），因此预计该研究将导致实现比目前在1.5 μ m光谱范围内可用的更快、更低功率的器件。 还预期这些器件将显示出上级温度稳定性，因为它们是基于子带间而不是带到带过程。 ***

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. ***