Fig. 5: Transmission measurements under optical feedback.
From: Exploring the feedback limits of quantum dot lasers for isolator-free photonic integrated circuits
a Experimental setup. MZM Mach–Zehnder modulator, PDFA praseodymium-doped fiber amplifier, SMF single mode fiber, PD photodetector, DCA digital communication analyzer, BERT bit error rate tester. Eye diagrams, SNR, and BER performance (b) at the critical feedback level and (c) after entering the CC region
