The 400 Series cameras do not use structured / coded light (the SR300 model does). Instead, they use a Stereo system made up of a pair of left and right IR imagers. The D415 uses the OmniVision OV2740 sensor for IR and RGB.
When you asked about the 'length' of the laser, I was uncertain whether you were referring to the sensor's focal length or the projector laser and its wavelength. So I have put tables below that contain both of these details. Left-click on the images to see them in full size.