I'm designing an experiment to measure the speed of light by turning a 200mw red laser on and off at 1MHz (50% duty cycle) using an arduino's CTC mode. I would detect the laser light reflecting back from a distant mirror using a photodiode, and with a dual channel oscilloscope I could detect the phase shift between the laser's voltage wave and the photodiode's voltage wave to measure the time taken for the light to travel.
Since arduino's GPIO pins cannot provide the high 300mA current that the laser requires, I tried to solve this problem by using a high frequency transistor to control the current supplied to the laser straight from the power source.
However I need some help because after some research, I found out that most transistors don't support such a high frequency. I looked at some MOSFETs such as the RD16HHF1 which supports 30MHz switching, but apparently the gate threshold voltage is 12.5V which the arduino doesn't provide.
How could I solve this problem so I can reliably control the 200mw laser at 1MHz? I'm open to any ideas.