High sensitive receiver module for 622 Mbps long span transmission

摘要

High sensitive receiver module for 622 Mbps optical transmission system has been developed. The receiver module consists of low noise pre-amplifier and an InGaAs avalanche photo diode (APD). A hetero-junction field effect transistor (HJFET) that has high transconductance and low input capacitance was applied as front end device. Trans-impedance type was adopted as pre-amplifier circuit. To reduce the equivalent input noise current, device performance of HJFET and InGaAs-APD were specified from noise calculation and receiver sensitivity simulation.Reducing the total input capacitance and optimizing the noise performance of pre-amplifier circuit, minimum sensitivity of -44.3 dBm for 1 × 10~(-9) bit error rate (BER) at the bit rate of 622 Mbps was attained. The minimum overload of -24 dBm was also accomplished by using the trans-impedance type pre-amplifier. The results indicate that high sensitive direct detection receiver is applicable in a long span transmission of more than 190km at the bit rate of 622 Mbps.