Nonlinear optical phase shift in InAs quantum dots measured by a unique two-color pump/probe ellipsometric polarization analysis
Nonlinear optical phase shift in InAs quantum dots measured by a unique two-color pump/probe ellipsometric polarization analysis
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通过独特的双色泵浦/探针椭偏偏振分析测量 InAs 量子点中的非线性光学相移
DOI：
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
K. Asakawa
中科院分区：
文献类型：
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作者：
H. Nakamura;K. Kanamoto;Y. Nakamura;S. Ohkouchi;H. Ishikawa;K. Asakawa
通过独特的双色泵浦/探针椭偏偏振分析测量了自组装 InAs 量子点 (QD) 在基态跃迁共振激发下的非线性光学相移。该椭偏分析利用了源自不对称结构的 SK-QD [(SK) — Stranski-Krastanov] 的大光学双折射。在具有峰值波长为1290nm、体积密度为4×1015cm-3、不均匀展宽为35meV的量子点的1mm长波导中，在输入泵浦脉冲能量密度为30pJ∕μm2、失谐为11meV、时间延迟为20ps时获得0.5πrad的相移。分析表明，相移主要归因于 TE 偏振光的吸收饱和，尽管其他机制也可能有助于更高的泵浦。基于两级近似的计算表明，理想条件下计算的π位移的最小能量密度为240fJ∕μm2。
The nonlinear optical phase shift in self-assembled InAs quantum dots (QDs) under resonant excitation in a ground-state transition was measured by a unique two-color pump∕probe ellipsometric polarization analysis. This ellipsometric analysis makes use of the large optical birefringence of SK-QD [(SK) — Stranski-Krastanov] originating from the asymmetric structure. A phase shift of 0.5π rad was obtained at an input pump pulse energy density of 30pJ∕μm2, a detuning of 11meV, and a time delay of 20ps in a 1mm long waveguide having QDs with a peak wavelength of 1290nm, a volume density of 4×1015cm−3, and inhomogeneous broadening of 35meV. Analysis revealed that the phase shift is mainly attributed to the absorption saturation for TE-polarized light, though other mechanisms also could contribute at higher pumping. The calculation, based on the two-level approximation, revealed that the minimum energy density for π shift is 240fJ∕μm2, calculated under ideal conditions.