68 GHz Bandwidth From a Monolithically Integrated Directly Modulated Laser With a Simple Active Feedback Scheme

High‐bandwidth directly modulated lasers (DMLs) are critical for cost‐effective optical interconnects, yet achieving top‐tier performance often requires complex and expensive fabrication processes. Here, we overcome this challenge by demonstrating a monolithically integrated DML based on a simple identical active layer (IAL) process that achieves a record‐breaking bandwidth for its class. By synergistically leveraging photon–photon resonance (PPR) and detuned‐loading (DL) effects through an engineered active feedback cavity, our device exhibits a 3 dB modulation bandwidth of 68.3 GHz and a fiber‐coupled output power of 33.27 mW. This performance surpasses that of previous active‐feedback DMLs and is highly competitive with more complex passive‐feedback schemes. The device's practical viability is confirmed through successful 50 Gb/s NRZ data transmission over 10 km of fiber with excellent signal integrity. This work establishes a clear pathway toward low‐cost, scalable, and high‐performance transmitters for next‐generation 800 G and 1.6 T optical networks.