Narrow-linewidth light sources have far-reaching applications from communication¹ to metrology^2,3,4. Benchtop linewidth reduction methods such as feedback^5,6 and feed-forward^7,8 schemes have been used to reduce the linewidth of lasers. The feedback scheme typically has a limited bandwidth and depends on the laser characteristics and the feed-forward scheme is highly sensitive to gain and delay mismatches. Here, we report the demonstration of an integrated nanophotonic phase noise filter, which can be placed after a low-cost laser to significantly suppress its phase noise independent of the light source. The hybrid-integrated electronic–photonic system measures and suppresses the phase noise of the input light using an electronic–photonic loop without interacting with the light source. Using the integrated phase noise filter, laser linewidth reduction from 2.55 MHz to 4 kHz and from 200 kHz to 320 Hz is demonstrated. The silicon photonic and complementary metal–oxide–semiconductor (CMOS) electronic chips were hybrid-integrated within a footprint of 3 mm².

窄线宽光源在通信¹到计量^2,3,4方面具有广泛的应用。台式线宽减少方法，例如反馈^5,6和前馈^7,8已经使用各种方案来减小激光器的线宽。反馈方案通常具有有限的带宽，并且取决于激光器的特性，前馈方案对增益和延迟失配非常敏感。在这里，我们报告了集成纳米光子相位噪声滤波器的演示，该滤波器可以放置在低成本激光器之后，以显着抑制其相位噪声，而与光源无关。混合集成的电子-光子系统使用电子-光子回路测量和抑制输入光的相位噪声，而无需与光源相互作用。使用集成的相位噪声滤波器，可以将激光线宽从2.55 MHz减小到4 kHz，从200 kHz减小到320 Hz。²。