This work investigates optically amplified bidirectional transmission with a quantum-dot semiconductor optical amplifier for next-generation 100G passive optical networks. We experimentally demonstrate 100/150 Gbit/s uplink/downlink bidirectional PAM-4 transmissions employing a quantum-dot semiconductor optical amplifier in the remote node of an optical access network. After 20 km optically amplified transmission, we attain the uplink/downlink power budgets of 32.3 dB/29 dB at the HD-LDPC bit error ratio decision threshold of 10−2 with an overhead of 15.5%, satisfying the power budget requirements of a legacy passive optical network with net (gross) achievable uplink/downlink data rates of 84.4/126.7 (100/150) Gbit/s, respectively.