I.R. LASER diode needs to be fed 2.2 volts, not 5 volts. You need a driver (constant current source) instead of that 5volt linear regulator, if you are talking a bare diode (not a module, where the driver is included). If you just want to drive it at 38KHz, you could use a NE555 oscillator to drive a MOSFET switching power to the LASER driver circuit. Since I'm betting that you want to use the LASER in I.R. Commo/remote-ctl., You might want to look into sourcing a driver for 808nm LASER diode, really cheap, and most already have provision for modulation (if it comes with a button switch, you remove the switch and replace it with a MOSFET(2N7000 I think) 'S' to + side, 'D' to return side, modulation signal to 'G' through a 1k resistor). If that's too much for you, try looking at LASERPOINTERFORUMS.COM, and do some searching and reading. Good luck and BE CAREFULL!!