Increasing the modulation speed of semiconductor lasers has attracted much attention from the viewpoint of both physics and the applications of lasers. Here we propose a membrane distributed reflector laser on a low-refractive-index and high-thermal-conductivity silicon carbide substrate that overcomes the modulation bandwidth limit. The laser features a high modulation efficiency because of its large optical confinement in the active region and small differential gain reduction at a high injection current density. We achieve a 42 GHz relaxation oscillation frequency by using a laser with a 50-μm-long active region. The cavity, designed to have a short photon lifetime, suppresses the damping effect while keeping the threshold carrier density low, resulting in a 60 GHz intrinsic 3 dB bandwidth (f_3dB). By employing the photon–photon resonance at 95 GHz due to optical feedback from an integrated output waveguide, we achieve an f_3dB of 108 GHz and demonstrate 256 Gbit s⁻¹ four-level pulse-amplitude modulations with a 475 fJ bit⁻¹ energy cost of the direct-current electrical input.

从物理学和激光器的应用的观点来看，提高半导体激光器的调制速度已经引起了很多关注。在这里，我们提出了一种克服了调制带宽限制的低折射率，高导热碳化硅衬底上的膜分布反射器激光器。该激光器具有高调制效率，这是因为其在有源区的光学限制较大，而在高注入电流密度下的差分增益减小较小。通过使用具有50μm长的有源区的激光器，我们可以达到42 GHz的弛豫振荡频率。设计为具有短光子寿命的腔，可抑制阻尼效应，同时保持较低的阈值载流子密度，从而产生60 GHz的固有3 dB带宽（f _3dB）。通过利用来自集成输出波导的光反馈，在95 GHz处采用光子-光子共振，我们实现了108 GHz的f _3dB，并以475 fJ bit ^-1的能量演示了256 Gbit s ^-1四级脉冲幅度调制直流电输入的成本。