In order to take into account the characteristics of the optical network unit and the transmission rate of the user end, an integrable coherent detection scheme was used to replace the traditional direct detection scheme at the receiving end. The bias characteristics of the electro-absorption modulator (EAM) was analyzed. A 5km bidirectional access network communication system with a rate of 40Gbit/s was built, and the transmission test of the integrable optical network unit with the distributed feedback (DFB) laser and the EAM as the upstream transmitter was carried out. Under the direct detection scheme and forward error correction (FEC), the receiving sensitivity of downstream signal and upstream signal of bidirectional transmission are -18.31dBm and -17.94dBm respectively. Under the coherent detection scheme and FEC, the receiving sensitivities of downstream and upstream signals are -32.51dBm and -29.76dBm, respectively. The results show that the upstream and downstream receiving sensitivities of the coherent detection scheme are 14.20dB and 11.82dB higher than those of the direct detection scheme, respectively. The result of this work provides a high-speed and large-scale deployment integrated scheme for the optical network unit of the future client.