基于太赫兹光非对称解复用器结构的低开关能量、高线性度全光采样门实验研究

Experimental study on a low switching energy and high-linearity all-optical sampler based on terahertz optical asymmetric demultiplexer

利用多量子阱结构的非线性半导体光放大器(SOA)构建的太赫兹光非对称解复用器(TOAD),实验实现了一个开关能量低至25 f J,线性度高达0.99的全光采样门.详细分析了采样脉冲功率和非对称偏移量分别对采样窗口形状、宽度和幅度的影响,并研究了不同采样窗口宽度下TOAD的开关能量及线性度的变化规律.

We demonstrate experimentally a low switching energy and high-linearity all-optical sampler based on terahertz optical asymmetric demultiplexer（TOAD） composed of a nonlinear semiconductor optical amplifier（SOA） with a multiple quantum well structure. Effects of the sampling pulse power and asymmetric offset of SOA on the shape, width and amplitude of sampling windows are analyzed in detail respectively. It is found that the sampling pulse power has no effect on both the shape and the width of sampling windows, but has a significant effect on the window amplitude. Meanwhile there exists an optimal power which maximizes the sampled output and determines the switching energy of TOAD. The asymmetric offset of SOA from the center position in the loop determines the width of sampling windows and has great influences on both the shape and the amplitude of the sampling window. The sampling windows with different widths have approximately the same rise edge due to the fast response of SOA for the sampling pulse. However, the normalized amplitude of sampling windows firstly increases sharply with the increase of the asymmetry, then gradually flattens out,and tends to be stable in the end. In addition, the switching energy and linearity of TOAD are studied. The switching energy is as low as 25 f J, and the linearity is as high as 0.99. Moreover, at different window widths, the switching energy of TOAD remains the same and the sampling windows have a very good linearity. However, the sensitivity of a TOAD sampler with different width is different： the wider the sampling window, the higher the sensitivity and the larger the corresponding dynamic range.