A broadband high dynamic range analog photonic link using push-pull directly-modulated semiconductor lasers

We demonstrate an analog photonic link with a high multioctave spurious-free dynamic range (SFDR) of 119 dBHz2/3. The link consists of a pair of semiconductor DFB lasers modulated in a push-pull manner and a balanced photodetector. With precise amplitude and phase matchings, a signal enhancement of 4.5 dB and a second-order intermodulation distortion suppression of 40 dB relative to the case of a single arm optical link with one laser can be achieved. To our knowledge, the measured SFDR is one of the highest broadband value ever achieved with directly modulated lasers. Index Terms—Intermodulation distortion, laser noise, optical modulation, semiconductor laser