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 dBHz^2/3. 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 inter-modulation 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.