Intersubband absorption spectra in the 10-$mu@m region are measured between 4.2 and 290 K in four n-type GaAs/Al$-0.28$/Ga$- 0.72$/As multiple-quantum-well samples. The carriers responsible for the absorption are generated by a cross-gap pump laser operating at 0.75 $mu@m. The absorption strength per unit pump power is found to depend strongly on the background electron sheet density $sigma$-B$/, and is greatest by far in a sample having $sigma$-B$/ $APEQ 4 $MUL 10$+10$/ cm$+$MIN@2$/. By measuring the speed of response, the cause of the strong photoabsorption is found to be a long photoelectron lifetime. The sample with the strongest photoabsorption is used to make an efficient CO$-2$/-laser modulator.
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机译：10-$ MU @ M区域中的间隙吸收光谱在4.2和290 k之间测量四个n型GaAs / Al $ -0.28 $ / GA $ - 0.72 $ /作为多量子阱样本。负责吸收的载体是由在0.75 $ MU @ M的交叉间隙泵激光器产生的。每单位泵电源的吸收强度被发现强烈地依赖于背景电子板密度$ sigma $-$ /，并且在具有$ sigma $-$ / $ apeq 4 $ mul 10 $ +的样本中最重要的是最重要的10 $ / cm $ + $ min @ 2 $ /。通过测量响应的速度，发现强烈的光吸收的原因是长光电子寿命。具有最强的光吸收的样本用于使高效的CO $ -2 $ / - 激光调制器。
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