High-speed Infrared UART link with photodiode
It is a bit more challenging. You need to protect your channel from variations in ambient light, which can be horrendous. That's why IrDA (infrared digital communication alliance) uses modulated light and a sophisticated automatic gain control system. Current IrDA standard extends the data rate to 4 Mbps, see the article. 


  The IrDA standard has successfully progressed from IrDA-1.0
  (115.2Kbps) to IrDA-1.1 (4Mbps) in the short two and half years. There
  are many components, adapters, software and mobile systems available
  for the IrDA-1.0 standard on the market now. The same will happen soon
  for IrDA-1.1 standard with the optoelectronic, analog and digital
  interface ASIC components already on the market.


Today at IrDA 1.4 there are "medium" IR (MIR) transeivers (1.152 mbps) TFDU5307, FIR (fast infrared 4 Mbps) transceivers like TFDU6300 which are still available. 



There were plans for VFIR (16 Mpps channels), but it looks like this direction didn't get enough industrial traction. VFIR transceiver TFDU8108 is however available.