An intersubband-transition (ISB-T) in a semiconductor quantum well (QW) has been drawing much attention due to its unique characteristics such as ultrafast energy relaxation time (/spl sim/1 ps) and large transition probability. In this paper, we report for the first time a picosecond range all-optical modulation by using a free electron laser (FEL) as the ISB-light. This has become possible by the attractive features ofthe FEL such as ultra-short pulse operation, wide tunability of the lasing wavelength, and high peak power keeping the average power low. The sample utilized for the experiment has a multiple quantum well structure with 30 periods of GaAs wells and Al/sub 0.3/Ga/sub 0.7/As barrier layers grown by molecular-beam epitaxy on a GaAs substrate, where the barrier layers were selectively n-doped with Si.
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机译:半导体量子阱(QW)中的子带间转换(ISB-T)由于其独特的特性(例如超快的能量弛豫时间(/ spl sim / 1 ps)和大的转换概率)而备受关注。在本文中,我们首次报告了使用自由电子激光(FEL)作为ISB光的皮秒级全光调制。 FEL的吸引人的特性(例如超短脉冲操作,激光波长的宽可调性以及高峰值功率使平均功率保持较低)已成为可能。用于实验的样品具有多量子阱结构,具有30个周期的GaAs阱和通过分子束外延在GaAs衬底上生长的Al / sub 0.3 / Ga / sub 0.7 / As势垒层,其中势垒层为n掺Si。
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