Bostani Ameneh, Ahlawat Meenu, Tehranchi Amirhossein, Morandotti Roberto, Kashyap Raman
Opt Express. 2013 Dec 2;21(24):29847-53. doi: 10.1364/OE.21.029847.
We demonstrate theoretically and experimentally, that the non-uniform spectra of second harmonic generation (SHG) from an unapodized step-chirped periodically poled nonlinear optical grating can be apodized utilizing tightly-focused Gaussian beams to suppress the ripple in its wideband response. In our example, by increasing focusing, a ripple-free response is progressively achieved over a 6-dB bandwidth of >5 nm, with a beam waist of 20 µm. With this tight focusing arrangement, a continuous tuning of 11-nm is also demonstrated by simply changing the focal point by 5.8 mm within the step-chirped grating based APPLN.
我们通过理论和实验证明，利用紧聚焦高斯光束可以对未变迹的步进啁啾周期性极化非线性光学光栅产生的二次谐波（SHG）的非均匀光谱进行变迹，以抑制其宽带响应中的纹波。在我们的示例中，通过增加聚焦，在大于5 nm的6 dB带宽上逐渐实现了无纹波响应，束腰为20 µm。通过这种紧聚焦配置，在基于步进啁啾光栅的应用中，仅通过在5.8 mm范围内简单地改变焦点，还展示了11 nm的连续调谐。
