Stablish uni-directional SFP network link

I am trying to establish a uni-directional Ethernet link where a singular fiber is used to transmit data to the receiver. The Rx of the transmit side and the Tx of the receive side are not physically connected, like in a Data diode scenario. The problem is, as soon as I detach the tx line from one side, both side link status goes DOWN. can anyone give advice to overcome this problem? do I need to change the Linux SFP driver to mask link status as always UP?