Narayanan Karthik, Preble Stefan F
Microsystems Engineering, Kate Gleason College of Engineering, Rochester Institute of Technology, Rochester, New York 14623, USA.
Opt Express. 2010 Apr 26;18(9):8998-9005. doi: 10.1364/OE.18.008998.
We experimentally measure the optical nonlinearities in hydrogenated-amorphous silicon (a-Si:H) waveguides through the transmission of ultra-short pulses. The measured two-photon absorption coefficient beta is 4.1 cm/GW and we obtain a 3.5pi nonlinear phase shift at 4.1 W coupled input power corresponding to a nonlinear refractive index n(2) of 4.210(-13) cm(2)/W. The measured nonlinear coefficient gamma = 2003 (Wm)(-1) is at least 5 times the value in crystalline silicon. The measured free carrier absorption coefficient sigma = 1.910(-16) cm(2) agrees with the values predicted from the Drude-Lorenz model. It is seen that a-Si:H exhibits enhanced nonlinear properties at 1550 nm and is a promising platform for nonlinear silicon photonics.
我们通过超短脉冲的传输，对氢化非晶硅（a-Si:H）波导中的光学非线性进行了实验测量。测得的双光子吸收系数β为4.1 cm/GW，在4.1 W的耦合输入功率下，我们获得了3.5π的非线性相移，对应于4.2×10⁻¹³ cm²/W的非线性折射率n(2)。测得的非线性系数γ = 2003 (Wm)⁻¹，至少是晶体硅中该值的5倍。测得的自由载流子吸收系数σ = 1.9×10⁻¹⁶ cm²，与德鲁德 - 洛伦兹模型预测的值相符。可以看出，a-Si:H在1550 nm处表现出增强的非线性特性，是用于非线性硅光子学的一个有前途的平台。
