Of course, this Light is not made of photons. It is not on the electromagnetic spectrum at all. But get this (and I repeat this verse intentionally):

For with You is the fountain of life;

In Your light we see light (Psa 36:9)

That is, only in this Light can we see (perceive, understand) this Light

For You will light my lamp;

The LORD my God will enlighten my darkness (Psa 18:28)

Your ‘lamp’ is your life, your soul, and without God’s help you exist in darkness.