I'm looking for inspiration to export data (simplex) / one-way) across a short air gap from a small device with a low energy budget, so trying to optimise for power. BLE seems like overkill and potentially too complex for the relatively quick development I'd like. I've had good success with 36/38kHz IR receivers in the past but would like to try and increase the available data rates if possible. Let's say 112500 baud for discussion's sake.
My idea would be to use 2x IR LEDs and opposing photodiodes or phototransistors (advice on deciding which component would be very welcome) with significant current constraint on the LEDs (to save battery) in a differential serial link. A bit like cutting a dual optocoupler down the middle and driving one LED with an inverted signal to the other LED.
But before I go down that path, other than the LIFI (too complex), IrDa (haven't completely ruled this out) and other free space optics high data rate systems like RONJA (http://ronja.twibright.com/) and the Koruza project (https://hackaday.com/2016/03/10/gigabit-ethernet-through-the-air/ - sadly seems to have abandoned it's OSH approach) is there anything out there I should be drawing inspiration from?
I should mention that I'm open to other methods of communication, but I'm looking for simplicity as well as low power. Thanks.
[EDIT: I'm sure there's lot's to be learned from e.g. @CNLohr 's and other's hacking on the Valve Lighthouse tech but it's probably beyond this application]