For receiving infrared signals you have to get a photo module. First you have to determine what range of infrared signal you want to receive with your serial port.Examples for equipment with consumer standard IR devices are CD players, DVD players, TVs, VCRs, Cable Boxes, Receivers, Tape Decks, DVRs, home automation, etc.
This simple circuit receives IR signals using TSOP 1738 photo module. You can use any IR module for your choice. TSOP 17-XX, SFH 506-XX series is a compatible module to receive IR remote control signals from COM ports on CD player, DVD player, TV, VCR, Cable Box, Receiver, Tape Deck, DVR, home automation, etc.
Photo modules TSOP 1730, TSOP1733,TSOP 1736, TSOP 1737, TSOP 1738, TSOP 1740, TSOP 1756 or you can try your old broken DVD Player!, VCR, TV or anything that have an IR remote controller. It should have 3 pins and 5V. Study your the photo module to know how to attach that device and use that pin connections this circuit.
IC1 = 78L05
IC2 = TSOP 1738
D1 = 1N4148
R1 = 4k7
C1 = 4.7uf