Hello and welcome to the forum!:wave:
Connecting diodes in series, the current stays the same as for one diode, but the driver
needs to be able to provide N. of diodes * Vf of single diode's voltage.
Connecting diode's in parallel, the voltage stays the same, but the current gets split
between the diodes so you need N. of diodes * mA for a single diode worth of current in total. Besides, you will need to add low resistance balancing resistors when driving them
in parallel to make sure every diode gets the same current.
Example:
to drive three 445nm diode in series, you'd need about 1000mA and 13~14 V
to drive the same diodes in parallel, you'd need about 3A and 4.5 V.
Have you read this already?
Laser driver - It can be done